A polytetrafluoroethylene two-color spiral heat shrink tube and preparation method thereof

Abstract

The present invention discloses a polytetrafluoroethylene two-color spiral heat shrinkable tube and a preparation method thereof; the method mainly comprises: (1) mixing two-color materials A and B; (2) preforming two-color blanks; (3) extruding paste; (4) drying, sintering, cooling; (5) heat treatment; (6) inflation. The two-color blanks adopt a detachable barrel, and after compaction, a uniform two-color blank dividing line parallel to the axis is obtained. The overall process is simple and efficient, and the prepared two-color spiral heat shrinkable tube has good dimensional stability, relatively uniform pitch, strong and lasting tinting power, and can be used with an endoscope or other equipment to effectively improve the navigation and positioning of medical staff in endoscopic medical treatment and reduce the pain of patients.

Description

Technical Field

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

[0002] In recent years, unlike traditional internal medicine and surgery, doctors in the interventional department use CT, MRI, ultrasound and other medical imaging equipment to guide them, and use specific instruments such as catheters and guidewires to reach the lesion site for diagnosis and treatment. They have the advantages of small incision, high accuracy and wide indications, and have been widely used. As a modern medical device, the endoscope is introduced into various natural cavities and minimally invasive interventions, and the endoscopic image is obtained by connecting imaging equipment or directly observing with the naked eye. Endoscopes are mainly used in the fields of digestive system, urinary system or respiratory system, gynecology, etc. In interventional medicine, the visible time and range are subject to certain restrictions, and it is difficult for the attending physician to accurately locate and quickly navigate the internal tissue through the cavity or other reference objects. To solve this problem, researchers and production workers have made many improvements to medical catheters, such as considering adding a coating directly to the medical catheter, but this method is difficult to achieve long-term non-fading of the coating and continuous good coloring power.

[0003] Polytetrafluoroethylene (PTFE) is a high-performance thermoplastic (also known as F4). It is widely used in medical heat shrink tubing because of 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 polytetrafluoroethylene tube ribbon coating and a polytetrafluoroethylene tube thereof, and the preparation process includes: ① Preparation and treatment of the polytetrafluoroethylene tube body; ② Modification of the ribbon pigment; ③ Coating of the ribbon pigment on the outer wall of the tube body; ④ Curing of the ribbon coating. In general, the manufacturing of modified coating materials and surface treatment of the tube improves the navigation and positioning of medical staff in endoscopic medical treatment by adding an annular ribbon marking coating on 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 ribbon coating, the uniformity of the thickness of the coating, the uneven edges of the ribbon, and the coloring ability is not durable. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a medical polytetrafluoroethylene two-color spiral heat shrink tube and a preparation method thereof in view of the deficiencies of the above-mentioned prior art. The polytetrafluoroethylene two-color spiral heat shrink tube has two colors alternating on the surface to form spiral stripes with a certain pitch; the preparation method is relatively simple and suitable for industrial production; the prepared tube has good dimensional stability and color uniformity, and long-lasting coloring ability, and can be used in conjunction with an endoscope or other equipment, so as to facilitate 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 alternately.

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

[0010] A method for preparing a medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0011] Step S1, A and B two-color mixing:

[0012] Step S11, putting the sieved polytetrafluoroethylene dispersion resin into a dry and clean barrel according to a certain proportion, adding extrusion aid oil and color paste A in sequence, mixing evenly, and ripening at a constant temperature to obtain color A mixed material;

[0013] Step S12, putting the sieved polytetrafluoroethylene dispersion resin into a dry and clean barrel according to a certain proportion, adding extrusion aid oil and color paste B in sequence, mixing evenly, and ripening at a constant temperature to obtain a B color mixed material;

[0014] Step S2: Preforming of two-color blanks:

[0015] The A-color mixed material and the B-color mixed material are respectively made into an A-color semi-circular ring column tube blank and a B-color semi-circular ring column tube blank, and the A-color semi-circular ring column tube blank and the B-color semi-circular ring column tube blank can be butted to form a two-color circular columnar blank;

[0016] Step S3: Pushing and extruding:

[0017] The A-color semicircular column tube blank and the B-color semicircular column tube blank obtained in step S2 are placed in the material cavity of the vertical extruder, the A-color semicircular column tube blank and the B-color semicircular column tube blank are docked to form a two-color circular columnar blank, and the blank is extruded through a die that is coaxial with the material cavity and rotates around the axis to obtain a two-color spiral prefabricated pipe;

[0018] Step S4: drying, sintering, and cooling:

[0019] The two-color spiral prefabricated pipe is sequentially dried, sintered, and naturally cooled to obtain a polytetrafluoroethylene two-color spiral pipe;

[0020] Step S5: heat treatment:

[0021] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat treated again;

[0022] Step S6, inflation:

[0023] After heat treatment, the polytetrafluoroethylene two-color spiral tube is quickly passed through an inflation machine to be filled with compressed gas, and then cooled;

[0024] Finally, a polytetrafluoroethylene two-color spiral heat shrink tube is obtained.

[0025] 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.

[0026] 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%.

[0027] 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 amount of polytetrafluoroethylene dispersion resin and extrusion-aid oil; the color paste B in step S12 is added in an amount of 0.2-1% of the total amount of polytetrafluoroethylene dispersion resin and extrusion-aid oil.

[0028] As a further improved technical solution of the present invention, in the step S4, the drying temperature is 100°C, the sintering temperature is 380-450°C, and the sintering time is 20-40 seconds; in the step S5, the heat treatment temperature is 360°C; in the step S6, after the heat treatment, it is quickly passed through an inflation machine, filled with compressed gas below 0.98MPa, the inflation rate is 200%-400%, and then cooled.

[0029] As a further improved technical solution of the present invention, in the step S2, a two-color circular cylindrical body is prepared using a cylinder;

[0030] The cylinder comprises a cylinder body; the cylinder body is a semicircular ring column, the side plane of the cylinder body is fitted with the inner surface of the partition, arc flanges extending parallel to the axis of the cylinder body are arranged on both sides of the partition, the arc flanges are fitted with the arc surface of the cylinder body, a semi-cylinder coaxial with the cylinder body is arranged on the inner surface of the partition, a blocking plate is arranged at one end of the axis 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;

[0031] A pressing block is provided at the other end of the axial direction of the cylinder body and the partition, and the pressing block is used to block the other end port of the internal space. The pressing block can move along the axial direction of the cylinder body under the action of external force to compress the mixed material in the internal space;

[0032] There are two cylinder bodies, which are respectively recorded as cylinder body one and cylinder body two. When the side plane of cylinder body one is fitted with the side plane of cylinder body two, a circular cylinder is formed.

[0033] The step S2 is specifically as follows:

[0034] Step S21: Assemble the cylinder body 1 and a partition together, fit the side plane of the cylinder body 1 with the inner surface of the partition, add the color A mixture into the internal space; use auxiliary tools to apply a certain pressure to the color A mixture so that the color A mixture in the internal space is shaped into a color A semi-circular ring column tube blank, remove the partition and the blocking plate, and the color A semi-circular ring column tube blank is not loose;

[0035] Step S22: Assemble the second cylinder body and a partition together, fit the side plane of the second cylinder body with the inner surface of the partition, add the B color mixture into the internal space; use auxiliary tools to apply a certain pressure to the B color mixture, so that the B color mixture in the internal space is shaped into a B color semi-circular ring column tube blank, remove the partition and the blocking plate, and the B color semi-circular ring column tube blank is not loose;

[0036] Step S23: Align and enclose the cylinder body containing the A-color semi-circular ring column tube blank with the cylinder body containing the B-color semi-circular ring column tube blank to obtain a circular ring column cylinder containing a two-color circular ring column tube blank; extrude the two-color circular ring column tube blank from the circular ring column cylinder through an extrusion device to obtain a two-color circular ring column blank.

[0037] As a further improved technical solution of the present invention, the vertical extruder in step S3 comprises an extruder head, a core die, a cone die and a rotatable die structure;

[0038] 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;

[0039] The rotatable die structure comprises a transmission shaft, a die flange, a die and a rotation drive mechanism, wherein 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 a die is connected in the die receiving groove; the rotation drive mechanism is transmission-connected to the transmission shaft to drive the transmission shaft and the die to rotate relative to the die flange;

[0040] The bottom of the cone die is connected to the top of the die flange, and the bottom of the cone die is rotatably contacted with the top of the die;

[0041] The center line of the material cavity of the extruder head, 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 transmission shaft are located on the same straight line;

[0042] The material cavity inside the extruder head, the inner cavity of the cone die, the inner cavity of the mouth die, and the central hole of the transmission shaft are connected in sequence;

[0043] The step S3 is specifically as follows:

[0044] The two-color circular cylindrical blank obtained in step S2 is placed in the material cavity of the extruder head, the extruder head, the cone die, and the rotatable die structure are connected in sequence, the extrusion drive mechanism connected to the piston in the extruder head is turned on, the extrusion drive mechanism applies a pushing force to the piston, and the rotation drive mechanism is turned on at the same time, 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 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 the two-color spiral prefabricated pipe is obtained after pushing.

[0045] The beneficial effects of the present invention are:

[0046] 1. To facilitate the addition of two-color mixed materials, the present invention uses a detachable cylinder during the pre-pressing process, including a cylinder body, a partition, etc. The two cylinder bodies can be connected to form an integrated cylinder, and flanges that can fit the arc surface of the cylinder body are arranged on both sides of the partition, and a raised semi-cylindrical structure is in the middle. This detachable barrel is easy to clean, clean and hygienic, and the device is simple and efficient. It can prefabricate a two-color blank with uniform color, and the junction of the two colors is basically parallel to the axis.

[0047] 2. In step S2, it is more convenient to prepare a semi-circular column tube blank using a semi-circular column tube blank preparation device composed of a cylinder body, a partition, a blocking plate, etc. Flanges that can fit with the arc surface of the cylinder body are arranged 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, so it is 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 is convenient for pre-pressing the mixture.

[0048] The semi-circular ring column tube blank can be prepared by using the semi-circular ring column tube blank preparation device. The semi-circular ring column tube blank is taken out from the preparation device, and two semi-circular ring column tube blanks of different colors are enclosed and butt-jointed to obtain a two-color tube blank, in which the two semi-circular ring column tube blanks of different colors are symmetrically distributed.

[0049] 3. When two cylinder bodies are used, 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 ring column tube blank from the cylinder body. The two cylinder bodies are butt-jointed into one cylinder, and at the same time, the two semi-circular ring column tube blanks are butt-jointed into a two-color circular ring column tube blank. The cylinder is detachably connected to the frame, and the extrusion cylinder can be used to extrude the two-color tube blank, which greatly improves the working efficiency.

[0050] 4. The transition connection ring is formed by the transition connection half ring 1 and the transition connection half ring 2 which are connected together, and the transition connection ring is detachably connected to the frame, which further improves the efficiency of connecting the cylinder to the frame. The transition connection half ring 1 is connected to the transition connection half ring 2, which also prevents the two cylinder bodies from separating.

[0051] 5. In step S3, the extruder adopts a rotatable die structure. When the extruder head is working, the two-color circular cylindrical blank is pushed along the cone die into the counterclockwise rotating die. The PTFE blank is mainly subjected to thrust and rotational force in the rotating die to form a PTFE two-color spiral prefabricated pipe. The extruded two-color spiral prefabricated pipe has good stability, uniform pitch, strong and durable tinting power; after drying, heat treatment and other operations in the later stage, the obtained two-color spiral pipe can be used for medical catheters.

[0052] 6. The process of the present invention is simple and efficient. A two-color spiral pre-compression 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.

[0053] 7. The two-color spiral heat shrink tubing prepared by the present invention has good dimensional stability, uniform pitch, strong and lasting coloring power, 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, accurately operate, and reduce the pain of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 , 2 They are three-dimensional diagrams of the cylinder body;

[0055] Figure 3 , 4 They are three-dimensional diagrams of the partitions;

[0056] Figure 5 It is a schematic diagram of the assembly of the partition plate, cylinder body, pressure block, etc.;

[0057] Figure 6 for Figure 5 DD cross-sectional view;

[0058] Figure 7 for Figure 5 EE cross-sectional view;

[0059] Figure 8 , 9 They are three-dimensional diagrams of the cylinder body connected to the extrusion device;

[0060] Fig.10 It is a front view of the cylinder body and the like of Example 1 connected to the extrusion device;

[0061] Fig.11 for Fig.10 AA section view;

[0062] Fig.12 for Fig.10 Left view of;

[0063] Fig.13 for Fig.10 CC section view;

[0064] Fig.14 , 15 They are three-dimensional diagrams of the cylinder body and the like connected to the extrusion device;

[0065] Fig.16 , 17 18 and 19 are three-dimensional diagrams of the stopper sleeve;

[0066] Fig.19 is a cross-sectional schematic diagram of an extruder;

[0067] Fig. 20 for Fig.19 A partial enlarged view of middle A;

[0068] Fig.21 This is a state diagram of the die rotating to form a two-color spiral prefabricated pipe.

[0069] Description of reference numerals:

[0070] 1. Cylinder body; 2. Partition plate; 21. Flanged edge; 22. Semi-cylinder; 3. Block plate; 4. Press block; 5. Transition connecting half ring; 6. Screw;

[0071] 11. Cylinder body 1; 12. Cylinder body 2; 13. Cylinder; 14. Side plane; 15. Screw hole; 16. Screw hole;

[0072] 51. Transition connection half ring 1; 52. Transition connection half ring 2; 53. Transition connection ring; 55. Clamping part 1; 56. Clamping part 2; 59. Transition connection screw;

[0073] 71, slot one; 72, slot two; 81, semi-circular ring column tube blank of color A; 82, semi-circular ring column tube blank of color B;

[0074] 9. stopper sleeve; 92. intermediate body; 91. front end plate; 93. rear stopper ring; 95. semi-ring groove 1; 96. semi-ring groove 2; 97. ring groove; 99. annular column stopper;

[0075] 100, extrusion device; 200, core rod; 300, piston; 400, frame; 500, oil cylinder;

[0076] 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, die flange; 1013, locking screw 2; 1014, die ; 1015, cone mold flange; 1016, core mold; 1017, cone mold; 1018, locking screw three; 1019, PTFE blank tube; 1020, piston; 1021, pushing tube; 1022, machine body; 1023, servo motor; 1024, planetary reducer; 1025, mounting plate; 1026, synchronous belt; 1027, synchronous pulley B; 1028, core mold connecting rod. DETAILED DESCRIPTION

[0077] The specific embodiments of the present invention are further described below according to the accompanying drawings: Example 1

[0078] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0079] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0080] Step S1: A and B two-color mixing;

[0081] Weigh the raw materials according to the weight ratio, 85 parts of polytetrafluoroethylene dispersion resin, 15 parts of extrusion aid oil. 1 part of white color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, first pre-mix the white color paste (i.e. color paste A) and extrusion aid oil, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a white mixture;

[0082] 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;

[0083] Step S2: preforming of two-color blank;

[0084] After aging, the white mixed material and the blue mixed material 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 cylindrical body;

[0085] Step S3: extruding the paste;

[0086] The two-color circular cylindrical blank obtained in step S2 is placed in a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0087] Step S4: drying, sintering, and cooling;

[0088] 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.

[0089] Step S5: heat treatment;

[0090] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360° C.

[0091] Step S6: inflation;

[0092] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 200%, and then cooled. Example 2

[0093] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0094] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0095] Step S1: A and B two-color mixing;

[0096] Weigh the raw materials according to the weight ratio, 80 parts of polytetrafluoroethylene dispersion resin, 20 parts of extrusion aid oil. 0.5 parts of white color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a white mixture;

[0097] Then the raw materials were weighed in the same manner, except that the color paste was yellow, to obtain a yellow mixed material;

[0098] Step S2: preforming of two-color blank;

[0099] After aging, the white mixed material and the yellow mixed material 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 cylindrical body;

[0100] Step S3: extruding the paste;

[0101] The two-color circular cylindrical blank obtained in step S2 is placed in a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0102] Step S4: drying, sintering, and cooling;

[0103] 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 sintering temperature of 410°C for 30 seconds; after sintering, the prefabricated pipe is naturally cooled at room temperature to obtain a polytetrafluoroethylene two-color spiral pipe.

[0104] Step S5: heat treatment; the polytetrafluoroethylene two-color spiral tube obtained in the above step S4 is heat treated again, and the heat treatment temperature is about 360°C;

[0105] Step S6: inflation;

[0106] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 200%, and then cooled. Embodiment 3:

[0107] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0108] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0109] Step S1: A and B two-color mixing;

[0110] Weigh the raw materials according to the weight ratio, 75 parts of polytetrafluoroethylene dispersion resin, 25 parts of extrusion aid oil. 0.2 parts of white color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a white mixture;

[0111] Then the raw materials were weighed in the same manner, except that the color paste was black, to obtain a black mixed material;

[0112] Step S2: preforming of two-color blank;

[0113] After aging, the white mixed material and the black mixed material 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 cylindrical body;

[0114] Step S3: extruding the paste;

[0115] The two-color circular cylindrical blank obtained in step S2 is placed in a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0116] Step S4: drying, sintering, and cooling;

[0117] 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.

[0118] Step S5: heat treatment;

[0119] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360° C.

[0120] Step S6: inflation;

[0121] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 300%, and then cooled. Embodiment 4:

[0122] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0123] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0124] Step S1: A and B two-color mixing;

[0125] Weigh the raw materials according to the weight ratio, 85 parts of polytetrafluoroethylene dispersion resin, 15 parts of extrusion aid oil. 1 part of white color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a white mixture;

[0126] Then the raw materials were weighed in the same way, except that the color paste was green, to obtain a green mixed material;

[0127] Step S2: preforming of two-color blank;

[0128] After aging, the white mixed material and the green mixed material 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 cylindrical blank;

[0129] Step S3: extruding the paste;

[0130] The two-color cylindrical blank obtained in step S2 is placed into a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0131] Step S4: drying, sintering, cooling, and stretching;

[0132] 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.

[0133] Step S5: heat treatment;

[0134] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360° C.

[0135] Step S6: inflation;

[0136] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 200%-400%, and then cooled. Embodiment 5:

[0137] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0138] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0139] Step S1: A and B two-color mixing;

[0140] Weigh the raw materials according to the weight ratio, 80 parts of polytetrafluoroethylene dispersion resin, 20 parts of extrusion aid oil. 0.5 parts of yellow color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, premix the yellow color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a yellow mixture;

[0141] Then the raw materials were weighed in the same way, except that the color paste was blue, to obtain a blue mixed material;

[0142] Step S2: preforming of two-color blank;

[0143] After aging, the yellow mixed material and the blue mixed material 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 cylindrical body;

[0144] Step S3: extruding the paste;

[0145] The two-color circular cylindrical blank obtained in step S2 is placed into a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0146] Step S4: drying, sintering, cooling, and stretching;

[0147] 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.

[0148] Step S5: heat treatment;

[0149] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360° C.

[0150] Step S6: inflation;

[0151] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 400%, and then cooled. Embodiment 6:

[0152] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the surface of the tube, and the spacing between the spiral stripes is adjustable.

[0153] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0154] Step S1: A and B two-color mixing;

[0155] Weigh the raw materials according to the weight ratio, 75 parts of polytetrafluoroethylene dispersion resin, 25 parts of extrusion aid oil. 0.2 parts of black color paste. Put the polytetrafluoroethylene dispersion resin into a dry and clean material barrel, premix the black color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin, mix the three evenly, and mature at a constant temperature of 25-30℃ for more than 12 hours to obtain a black mixed material;

[0156] Then the raw materials were weighed in the same manner, except that the color paste was yellow, to obtain a yellow mixed material;

[0157] Step S2: preforming of two-color blank;

[0158] After aging, the black mixed material and the yellow mixed material 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 cylindrical body;

[0159] Step S3: extruding the paste;

[0160] The two-color circular cylindrical blank obtained in step S2 is placed in a material cavity of an extruder and subjected to paste extrusion to obtain a two-color spiral prefabricated pipe;

[0161] Step S4: drying, sintering, cooling, and stretching;

[0162] 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.

[0163] Step S5: heat treatment;

[0164] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360° C.

[0165] Step S6: inflation;

[0166] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98MPa, with an inflation rate of 400%, and then cooled.

[0167] In addition to Examples 1-6, the two colors of the spiral stripes of the medical polytetrafluoroethylene two-color spiral heat shrink tube can also be at least one of black to green, yellow to blue, yellow to green, and blue to green.

[0168] In Examples 1-6, the purpose of heat treatment is: the thermoplastic material is in a glassy state at room temperature and becomes a highly elastic state after heating. The purpose of heat treatment is to make the thermoplastic pipe molten when heated (the melting point of polytetrafluoroethylene is 330°C), so that the pipe can be easily deformed and expand in the radial direction. The purpose of inflation: in order to conveniently and quickly wrap tightly around the parts that need to be protected, the pipe needs to expand radially. The material of the heat shrink tube becomes a highly elastic state when heated, and a load is applied to make it expand radially. It is quickly cooled while maintaining the radial expansion state to make it enter the glassy state. The inflated pipe is heat-shrunk and then wrapped to have a wrapping force to wrap the internal core material tightly.

[0169] In Example 1-6, in step S2, the cylinder 13 in the two-color tube blank preparation device is used for preforming, referring to Figure 5-8 The two-color tube blank preparation device includes a cylinder 13, a partition 2, a plugging plate 3, a pressing block 4, a transition connection half ring 5, a screw 6, etc. The cylinder 13 includes a cylinder body 1. The cylinder body 1, the partition 2, the plugging plate 3, the pressing block 4, and the transition connection half ring 5 are all two, and the structure is basically the same.

[0170] 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 .

[0171] See also Figure 1-4 The cylinder body 1 is a semicircular column, and the side plane 14 of the cylinder body is in contact with the inner surface of the partition 2. Arc flanges 21 extending parallel to the axis of the cylinder body 1 are arranged on both sides of the partition 2. The arc flanges 21 are in contact with part of the arc surface of the cylinder body 1. 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 arranged 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 at one end of the partition 2, and 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.

[0172] A pressure block 4 is provided at the other end of the cylinder body 1 and the partition plate 2 in the axial direction. The pressure block 4 is used to block 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.

[0173] 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 column cylinder 13 .

[0174] 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.

[0175] A clamping groove 71 is formed on the outer surface of one end of the cylinder body 11, a clamping groove 72 is formed on the outer surface of one end of the cylinder body 2, a clamping portion 55 is formed on the transition connection half ring 1 51 and a clamping portion 56 is formed on the transition connection half ring 2 52. The detachable connection method between the transition connection half ring 1 and the transition connection half ring 2 is similar to that between the two cylinder bodies and will not be described in detail.

[0176] 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 butted together to form a cylinder, the semi-annular groove 1 and the semi-annular groove 2 form an annular groove 97 on the cylinder.

[0177] The transition connection half ring 1 and the transition connection half ring 2 are provided with through holes for passing screws.

[0178] In Examples 1-6, the step S2 comprises the following steps:

[0179] Step S21, see Figure 5-7 and Fig.13 , prepare the A-color semi-circular ring column tube blank 81: insert the cylinder body 11 into the partition 2 along the axial direction until the plugging plate 3 blocks the port at one end of the internal space surrounded 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 the A-color mixture into the internal space; use auxiliary tools or pressing blocks to apply a certain pressure to the A-color mixture so that the A-color mixture in the internal space is shaped to form the A-color semi-circular ring column tube blank 81, and remove the auxiliary tools or pressing blocks. Pull the partition along the axis to separate the partition from the cylinder body 11, and obtain the cylinder body 11 containing the A-color semi-circular ring column tube blank 81 inside.

[0180] Step S22, using a method similar to the above, add the B color mixed material into the inner surface of the cylinder body 12, the inner surface of another partition 2, and the internal space surrounded by the outer arc surface of the semi-cylinder to prepare the cylinder body 12 containing the B color semi-circular ring column tube blank 82 inside.

[0181] Step S23, see Figure 8-13The cylinder body 11 containing the A-color semicircular ring column tube blank 81 and the cylinder body 2 12 containing the B-color semicircular ring column tube blank 82 are enclosed and docked, and the cylinder body 11 and the cylinder body 2 12 are docked to form a cylinder 13, and the A-color semicircular ring column tube blank 81 and the B-color semicircular ring column tube blank 82 are docked to form a two-color circular ring column tube blank. When enclosed and docked, the core rod 200 in the extrusion device 100 passes through the center of the circular ring column tube blank. The cylinder body 11 and the cylinder body 2 12 are connected together by screws 6.

[0182] Step S24, the clamping part 1 55 on the transition connection half ring 1 51 extends into the clamping groove 1 71, and the clamping part 2 56 on the transition connection half ring 2 52 extends into the clamping groove 2 72, and the transition connection half ring 1 51 is connected to the transition connection half ring 2 52 by screws 6, and the transition connection half ring 1 51 and the transition connection half ring 2 52 are connected to the frame 400 of the extrusion device by the transition connection screws 59 passing through the through holes. The piston 300 in the extrusion device is slidably arranged on the core rod 200, and the piston matches the cylinder.

[0183] Step S25, the oil cylinder 500 in the extrusion device is activated, and the piston 300 moves along the core rod in the cylinder barrel 13 to extrude the two-color circular ring column tube blank from the cylinder barrel.

[0184] The diameter (inner diameter) of the cylinder is 30 mm, and the thickness of the partition 2 is 1.5 m; each cylinder body is provided with 6 screw holes, which are staggered. The cylinder body is made of stainless steel.

[0185] See also Figure 14-15 The two-color tube blank preparation device in step S2 may also include a circular column stopper 99 formed by two semicircular column stoppers encircling and butting together, and a stopper sleeve 9 detachably connected to the cylinder barrel. Figure 16-18 The retaining sleeve 9 includes a front end plate 91, a rear retaining ring 93, and an intermediate body 92 connecting the front end plate and the rear retaining ring; the front end plate, the rear retaining ring, and the intermediate body are all provided with openings extending in the radial direction of the retaining sleeve, the opening width on the front end plate 91 is consistent with the outer diameter of the core rod 200, the opening width on the rear retaining ring 93 is consistent with the outer diameter of the annular groove 97, and the opening width on the intermediate body 92 is consistent with the outer diameter of the cylinder.

[0186] In Examples 1-6, the step S2 comprises the following steps:

[0187] Step S21, see Figure 5-7 and Fig.13, prepare the A-color semi-circular ring column tube blank 81: insert the cylinder body 11 into the partition 2 along the axial direction until the plugging plate 3 blocks the port at one end of the internal space surrounded 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 the A-color mixture into the internal space; use auxiliary tools or pressing blocks to apply a certain pressure to the A-color mixture so that the A-color mixture in the internal space is shaped to form the A-color semi-circular ring column tube blank 81, and remove the auxiliary tools or pressing blocks. Pull the partition along the axis to separate the partition from the cylinder body 11, and obtain the cylinder body 11 containing the A-color semi-circular ring column tube blank 81 inside.

[0188] Step S22, using a method similar to the above, add the B color mixed material into the inner surface of the cylinder body 12, the inner surface of another partition 2, and the internal space surrounded by the outer arc surface of the semi-cylinder to prepare the cylinder body 12 containing the B color semi-circular ring column tube blank 82 inside.

[0189] Step S23, see Figure 8-13 The cylinder body 1 containing the A-color semicircular ring column tube blank 81 and the cylinder body 2 containing the B-color semicircular ring column tube blank 82 are enclosed and docked, the cylinder body 11 and the cylinder body 2 12 are docked to form the cylinder 13, and the A-color semicircular ring column tube blank 81 and the B-color semicircular ring column tube blank 82 are docked to form a two-color circular ring column tube blank. When enclosed and docked, the core rod 200 in the extrusion device 100 passes through the center of the two-color circular ring column tube blank. The cylinder body 11 and the cylinder body 2 12 are connected together by screws 6.

[0190] Step S24, the clamping part 1 55 on the transition connection half ring 1 51 extends into the clamping groove 1 71, and the clamping part 2 56 on the transition connection half ring 2 52 extends into the clamping groove 2 72, and the transition connection half ring 1 51 is connected to the transition connection half ring 2 52 by screws 6, and the transition connection half ring 1 51 and the transition connection half ring 2 52 are connected to the frame 400 of the extrusion device by the transition connection screws 59 passing through the through holes. The piston 300 in the extrusion device is slidably arranged on the core rod 200, and the piston matches the cylinder.

[0191] Step S25, see Figure 14-15 ,refer to Figure 8-13 , two semi-circular annular column blocks are inserted into the extrusion port of the cylinder 13 away from the piston, and the two semi-circular annular column blocks surround the core rod 200 to form an annular column block 99; the stopper sleeve 9 is inserted into the cylinder 13 along the radial direction, the front end plate 91 is located at the end face of the extrusion end of the cylinder 13, and the rear stopper ring 93 extends into the annular groove 97 on the cylinder; start the hydraulic cylinder, the piston moves along the core rod 200 in the cylinder 13, and squeezes the tube blank toward the block direction to obtain a further compacted tube blank; the two-color tube blank has uniform color, and the junction of the two colors is basically parallel to the axis, which provides a basis for the later preparation of a two-color spiral heat shrink tube with uniform color. Then remove the stopper sleeve 9 from the cylinder 13 and remove the block.

[0192] The material chamber of the extruder in step S3 is connected to the extrusion end of the cylinder, the hydraulic cylinder is started, the piston moves along the core rod in the cylinder, and the two-color circular cylindrical tube blank is extruded from the cylinder 13 into the material chamber of the extruder, and the subsequent polytetrafluoroethylene two-color spiral tube preparation process is carried out.

[0193] 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 ripening 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 ripening them at a constant temperature to obtain the color B mixture.

[0194] In Examples 1-6, Figure 19-20 As shown, the extruder in step S3 includes an extruder head, a core die 1016, a cone die 1017 and a rotatable die structure.

[0195] like Figure 19-20 As shown, 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 piston 1020. A material cavity is provided inside the body 1022, and the core mold connecting rod 1028 is installed on the axis line inside the body 1022. The pushing tube 1021 is connected to the piston 1020. The pushing tube 1021 and the piston 1020 are located on the inner side of the material cavity and are used to be driven by a power element 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.

[0196] A lower groove is provided at the bottom of the machine body 1022, 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 screws 1018.

[0197] like Figure 1-2 As shown, the rotatable die structure includes a transmission shaft 104, a die flange 1012, a die 1014 and a rotation drive mechanism, the rotation drive mechanism is in transmission connection with the transmission shaft 104, the transmission shaft 104 is rotatably connected with the center hole of the die flange 1012, a die receiving groove is provided on the top of the transmission shaft 104, the die 1014 is connected in the die receiving groove, and the transmission shaft 104 is connected to the die 1014 through a convex end locking screw 1010. The core die 1016 is located in the inner cavity of the cone die 1017 and the inner cavity of the die 1014. The bottom of the core die 1016 is flush with the bottom of the die 1014.

[0198] 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 rotatably in contact with the top of the die 1014.

[0199] 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.

[0200] 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 .

[0201] The rotary drive mechanism adopts a servo motor 1023. The servo motor 1023 is connected to a synchronous pulley B1027 through 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 through a synchronous belt 1026. The synchronous pulley A103 is connected to one end of the transmission shaft 104 through a flat key 102.

[0202] The mounting plate 1025 is connected with a bearing seat 108, and the transmission shaft 104 passes through the center hole of the bearing seat 108 and the die flange 1012. The transmission shaft 104 and the bearing seat 108 are rotatably connected through a deep groove ball bearing 106, and the transmission shaft 104 and the center hole of the die flange 1012 are rotatably connected through 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 through a locking screw 107.

[0203] 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, and the 4 convex end locking screws 1 010 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.

[0204] The locking screws 1013 are installed on the mouth die flange 1012, and there are four locking screws 1013. The cone die flange 1015 is provided with 8 screw holes corresponding to the locking screws 1013 and the locking screws 1018. The mouth die flange 1012 is connected to the screw holes on the cone die flange 1015 through the locking screws 1013. A card interface (lower groove) with the cone die 1017 is provided below the material cavity. The inner cavity of the cone die 1017 has a certain cone angle, and the cone angle is 20° or 30°. The inner cavity of the mouth 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 screws 1018.

[0205] 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, and then install the plane bearing 109, install the transmission shaft 104 in the die flange 1012, and then install the deep groove ball bearing 1011. The three bearings and the transmission 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, and the locking screw 1013 is used to align the cone die flange 10 15, clamp it, use flat key 102 to fix synchronous pulley A103 and transmission shaft 104, then put PTFE blank tube 1019 (two-color circular cylindrical blank) into the material cavity, align cone die flange 1015 with the lower groove, and then use locking screw three 1018 to fix cone die flange 1015. Finally, install planetary reducer 1024 on mounting plate 1025, install synchronous pulley B1027 on the lower part of planetary reducer 1024, connect the two pulleys with synchronous belt 1026, and connect planetary reducer 1024 to servo motor 1023. The drive device and servo motor 1023 of the vertical extruder are both connected with power supply equipment.

[0206] In Examples 1-6, the step S3 is specifically as follows:

[0207] The two-color circular cylindrical blank obtained in step S2 is placed in the material cavity of the extruder head, the extruder head, the cone die, and the rotatable die structure are connected in sequence, the extrusion drive mechanism connected to the piston in the extruder head is turned on, the extrusion drive mechanism applies a pushing force to the piston, and the servo motor 1023 is turned on at the same time, the gear position of the planetary reducer 1024 is adjusted, and the servo motor 1023 drives the die to rotate through the transmission shaft, so that the blank (also referred to as the PTFE blank tube 1019) in the material cavity is subjected to the pushing force of the piston, passes through the cone die and enters the die in a rotating state, and the paste blank is passively subjected to force and rotates, and a two-color spiral prefabricated pipe (also referred to as the PTFE capillary 101) is obtained after pushing. The extrusion drive mechanism and the servo motor 1023 of the extruder are both connected to a power supply device.

[0208] The above-mentioned embodiments only express several implementation methods of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, any number of variations and improvements, without departing from the concept of the present application, belong to the protection scope of the present application.

Claims

1. A method for preparing a polytetrafluoroethylene two-color spiral heat shrinkable tube, characterized in that: The steps include: Step S1, A and B two-color mixing: Step S11, putting the sieved polytetrafluoroethylene dispersion resin into a dry and clean barrel according to a certain proportion, adding extrusion-aiding oil and color paste A in sequence, mixing evenly, and ripening at a constant temperature to obtain color A mixed material; Step S12, putting the sieved polytetrafluoroethylene dispersion resin into a dry and clean barrel according to a certain proportion, adding extrusion aid oil and color paste B in sequence, mixing evenly, and ripening at a constant temperature to obtain a B color 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 ring column tube blank and a B-color semi-circular ring column tube blank, and the A-color semi-circular ring column tube blank and the B-color semi-circular ring column tube blank can be butted together to form a two-color circular columnar blank; Step S3: Pushing and extruding: The A-color semicircular column tube blank and the B-color semicircular column tube blank obtained in step S2 are placed in the material cavity of the vertical extruder, the A-color semicircular column tube blank and the B-color semicircular column tube blank are docked to form a two-color circular columnar blank, and the blank is extruded through a die that is coaxial with the material cavity and rotates around the axis to obtain a two-color spiral prefabricated pipe; Step S4: drying, sintering, and cooling: The two-color spiral prefabricated pipe is sequentially dried, sintered, and naturally cooled 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 an inflation machine to be filled with compressed gas, and then cooled; Finally, a polytetrafluoroethylene two-color spiral heat shrink tube is obtained; In the step S2, a two-color circular cylindrical body is prepared using a cylinder; The cylinder comprises a cylinder body; the cylinder body is a semicircular ring column, the side plane of the cylinder body is fitted with the inner surface of the partition, arc flanges extending parallel to the axis of the cylinder body are arranged on both sides of the partition, the arc flanges are fitted with the arc surface of the cylinder body, a semi-cylinder coaxial with the cylinder body is arranged on the inner surface of the partition, a blocking plate is arranged at one end of the axis 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 pressing block is provided at the other end of the axial direction of the cylinder body and the partition, and the pressing block is used to block the other end port of the internal space. The pressing block can move along the axial direction of the cylinder body under the action of external force to compress the mixed material in the internal space; There are two cylinder bodies, which are respectively recorded as cylinder body one and cylinder body two. When the side plane of cylinder body one is fitted with the side plane of cylinder body two, a circular cylinder is formed. The step S2 is specifically as follows: Step S21: Assemble the cylinder body 1 and a partition together, fit the side plane of the cylinder body 1 with the inner surface of the partition, add the color A mixture into the internal space; use auxiliary tools to apply a certain pressure to the color A mixture so that the color A mixture in the internal space is shaped into a color A semi-circular ring column tube blank, remove the partition and the blocking plate, and the color A semi-circular ring column tube blank is not loose; Step S22: Assemble the second cylinder body and a partition together, fit the side plane of the second cylinder body with the inner surface of the partition, add the B color mixture into the internal space; use auxiliary tools to apply a certain pressure to the B color mixture, so that the B color mixture in the internal space is shaped into a B color semi-circular ring column tube blank, remove the partition and the blocking plate, and the B color semi-circular ring column tube blank is not loose; Step S23: a cylinder body containing the semi-circular ring column tube blank of color A is butted and enclosed with a cylinder body containing the semi-circular ring column tube blank of color B to obtain a circular ring column cylinder containing a two-color circular ring column tube blank, and the two-color circular ring column tube blank is extruded from the circular ring column cylinder by an extrusion device to obtain a two-color circular ring column blank; The vertical extruder in step S3 comprises 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 comprises a transmission shaft, a die flange, a die and a rotation drive mechanism, wherein 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 a die is connected in the die receiving groove; the rotation drive mechanism is transmission-connected to 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 is rotatably contacted with the top of the die; The center line of the material cavity of the extruder head, 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 transmission 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 central hole of the transmission shaft are connected in sequence; The step S3 is specifically as follows: The two-color circular cylindrical blank obtained in step S2 is placed in the material cavity of the extruder head, the extruder head, the cone die, and the rotatable die structure are connected in sequence, the extrusion drive mechanism connected to the piston in the extruder head is turned on, the extrusion drive mechanism applies a pushing force to the piston, and the rotation drive mechanism is turned on at the same time, 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 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 the two-color spiral prefabricated pipe is obtained after pushing.

2. The method for preparing the polytetrafluoroethylene two-color spiral heat shrinkable tube 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 the polytetrafluoroethylene two-color spiral heat shrinkable tube according to claim 1, characterized in that: In the step S11, the weight ratio is: 75-85% of polytetrafluoroethylene dispersion resin and 15-25% of extrusion aid oil; in the step S12, the weight ratio is: 75-85% of polytetrafluoroethylene dispersion resin and 15-25% of extrusion aid oil.

4. The method for preparing the polytetrafluoroethylene two-color spiral heat shrinkable tube 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 amount of polytetrafluoroethylene dispersion resin and extrusion-aiding oil; the color paste B in step S12 is added in an amount of 0.2-1% of the total amount of polytetrafluoroethylene dispersion resin and extrusion-aiding oil.

5. The method for preparing the polytetrafluoroethylene two-color spiral heat shrinkable tube 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, filled with compressed gas below 0.98MPa, with an inflation rate of 200%-400%, and then cooled.

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