CN111016235B - Porous PTFE (Polytetrafluoroethylene) stretched pipe and manufacturing process and application thereof - Google Patents
Porous PTFE (Polytetrafluoroethylene) stretched pipe and manufacturing process and application thereof Download PDFInfo
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- CN111016235B CN111016235B CN201911319766.5A CN201911319766A CN111016235B CN 111016235 B CN111016235 B CN 111016235B CN 201911319766 A CN201911319766 A CN 201911319766A CN 111016235 B CN111016235 B CN 111016235B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D23/00—Producing tubular articles
- B29D23/001—Pipes; Pipe joints
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
- B29K2027/18—PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene
Abstract
The invention relates to a porous PTFE (polytetrafluoroethylene) stretched tube and a manufacturing process and application thereof. The manufacturing process comprises oil mixing, preforming, extruding, drying, heat treatment, stretching and heat setting, wherein the dried PTFE extruded pipe is subjected to heat treatment above the initial melting temperature of PTFE, and the crystallization conversion rate of the PTFE extruded pipe with small wall thickness and large outer diameter is kept within a certain range by adjusting the temperature and time of the heat treatment, so that the PTFE extruded pipe is partially melted and sintered, the surface hardness of the PTFE extruded pipe is improved, and the problem of deformation or longitudinal cracking of the extruded pipe during stretching is finally solved. The invention has the advantages of simple manufacturing process, good stability, good repeatability, easy operation and strong practicability.
Description
Technical Field
The invention belongs to the technical field of processing and manufacturing of PTFE (polytetrafluoroethylene) stretched tubes, and particularly relates to a porous PTFE stretched tube and a manufacturing process and application thereof.
Background
Polytetrafluoroethylene, namely PTFE, also known as "plastic king", has excellent comprehensive properties such as high temperature resistance, corrosion resistance, non-adhesiveness, self-lubricity, excellent dielectric property, very low friction coefficient, etc., and the hollow fiber membrane prepared by the polytetrafluoroethylene has the advantages of strong hydrophobicity, oxidation resistance, acid and alkali resistance, temperature resistance, good biocompatibility, etc., is particularly suitable for various aspects such as membrane distillation seawater desalination, membrane seawater bromine extraction, membrane gas treatment, medical artificial blood vessels, etc., is an ideal material in the fields of biology, medicine, environmental protection, chemical industry, etc., and is increasingly favored by people along with the increasing environmental protection situation.
Since PTFE has a relatively high melt viscosity, conventional film-forming processes cannot be used. At present, research on a preparation process of a PTFE hollow fiber membrane mainly focuses on two aspects: the first is the electrostatic spinning method and the second is the drawing method. The electrostatic spinning method is a method for preparing spinning solution, and then obtaining the PTFE hollow fiber membrane through electrostatic spinning and sintering, and the method has the main defects that a spinning carrier needs to be removed through high-temperature sintering to obtain a microporous structure, the energy consumption and the time consumption are high, and the porosity of the membrane is low; the stretching method combines a paste extrusion process and a stretching process of PTFE, and obtains a hollow fiber membrane with a corresponding pore structure by controlling conditions such as stretching magnification, stretching temperature and the like, but when the method is adopted, the outer diameter of an extruded tube is smaller and the wall thickness ratio is larger, because the phenomena of deformation and cracking of the extruded tube can occur when the extruded tube with large outer diameter and small wall thickness is used for stretching. Since the PTFE hollow fiber membrane has a remarkable advantage, research on a microporous stretching control technology and stretching equipment for the PTFE hollow fiber membrane has been gradually developed in recent years at home and abroad.
Chinese patent document CN101797484A discloses a preparation method of polytetrafluoroethylene tubular membrane, which is formed by extending polytetrafluoroethylene resin unidirectionally or bidirectionally to form a membrane and setting at a supercritical temperature, wherein the setting temperature is 340-.
Chinese patent document CN102961976A discloses a polytetrafluoroethylene hollow fiber porous membrane and a preparation method thereof, the preparation steps are: preparing a primary PTFE hollow fiber, performing heat treatment, stretching pore-forming and sintering and shaping, wherein the heat treatment temperature is 200-.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a porous PTFE (polytetrafluoroethylene) stretched pipe and a manufacturing process and application thereof, and solves the problems that a PTFE extruded pipe with the outer diameter larger than 5.0mm and the wall thickness of 0.5-1.5 mm is easy to deform and longitudinally crack under the action of longitudinal traction force and stress, and finally cannot be stretched or is not uniformly stretched.
The technical scheme of the invention is as follows:
a manufacturing process of a porous PTFE stretched tube comprises the following steps:
(1) mixing oil, preforming, extruding and drying PTFE dispersion resin to obtain a PTFE extruded tube with the outer diameter larger than 5.0 mm;
(2) carrying out heat treatment on the PTFE extruded pipe obtained in the step (1), wherein the heat treatment temperature is 320-340 ℃, and the heat treatment time is 0.5-20 min;
(3) stretching the PTFE extruded tube subjected to the heat treatment in the step (2), wherein the stretching temperature is 220-290 ℃, and the stretching ratio is 1.0-5.0 times;
(4) and (4) carrying out heat setting on the stretched PTFE extruded pipe under tension to obtain the porous PTFE stretched pipe.
According to the invention, the PTFE extruded pipe in the step (1) has an outer diameter of 5.5-16.0 mm and a wall thickness of 0.5-1.5 mm.
According to the invention, the temperature of the heat treatment in step (2) is above the initial melting temperature of the PTFE; preferably, the heat treatment temperature in the step (2) is 331-338 ℃, and the heat treatment time is 0.5-5 min.
According to the present invention, it is preferable that the porous PTFE stretched tube has a crystallization conversion rate of 0.20 to 0.70 after heat treatment before stretching; more preferably 0.40 to 0.60.
According to the invention, the drawing temperature in the step (3) is preferably 240-280 ℃, and the drawing ratio is preferably 3-5 times.
According to the invention, the heat setting temperature in the step (4) is 380-390 ℃, and the heat setting time is 1-10 min.
In the invention, the calculation formula of the crystallization conversion rate is as follows: the crystal conversion rate was (S1-S3)/(S1-S2), where S1 is a shaded area of a melting peak of the porous stretched PTFE tube before heat treatment, S2 is a shaded area of a melting peak of the porous stretched PTFE tube after heat setting, and S3 is a shaded area of a melting peak of the porous stretched PTFE tube after heat treatment.
The porous PTFE stretched pipe prepared by the manufacturing process has the advantages that the outer diameter of the porous PTFE stretched pipe is 3.5-15.0 mm, the wall thickness is 0.3-1.3 mm, the porosity is 60-90%, the tensile strength is 40-55MPa, and the elongation is 50-150%.
Use of the above porous stretched PTFE tube as a medical tube, a chemical tube or a water treatment tube.
In the invention, the oil mixing, preforming, extruding, drying and heat setting are carried out according to the conventional operation in the field.
The invention has the technical characteristics that:
the key process of the invention is a heat treatment process before stretching, the PTFE dispersion resin is mainly characterized by having certain fiber forming property, when the PTFE dispersion resin passes through a conical die of an extruder, fibers with certain quantity and quality are formed and oriented in the extrusion direction due to the existence of stress and the friction among particles, so that the longitudinal fibrosis degree of the PTFE extrusion pipe is greater than that in the transverse direction, and the PTFE extrusion pipe with small wall thickness and large caliber is easy to deform or crack due to less transverse fibrosis and incapability of bearing larger stress when the PTFE extrusion pipe is stretched. According to the invention, the dried PTFE extruded pipe is subjected to heat treatment above the initial melting temperature of PTFE, and the crystallization conversion rate of the PTFE extruded pipe with small wall thickness and large outer diameter is within a certain range by adjusting the temperature and time of the heat treatment, so that the PTFE extruded pipe is partially melted and sintered, the surface hardness of the PTFE extruded pipe is improved, and the problem of deformation or longitudinal cracking of the extruded pipe during stretching is finally solved.
The invention has the beneficial effects that:
the invention provides a manufacturing process of a porous PTFE (Polytetrafluoroethylene) stretched pipe with stable production and good process repeatability, which changes the crystallization conversion rate of the PTFE extruded pipe by controlling the heat treatment temperature and time of the PTFE extruded pipe, solves the technical problem that the extruded pipe with large outer diameter and small wall thickness is easy to deform or longitudinally crack when being longitudinally stretched, has controllable density and excellent uniformity, can be widely used as medical pipes, chemical pipes, water treatment pipes and the like, and has simple manufacturing process, good stability, good repeatability, easy operation and strong practicability.
Detailed Description
The present invention is further described with reference to the following specific examples, wherein the steps and methods used in the examples are intended to illustrate the technical solutions of the present invention, but not to limit the present invention. The starting materials used in the examples are, unless otherwise specified, commercially available products.
In the examples, the calculation formula of the crystallization conversion is: the crystal conversion rate was (S1-S3)/(S1-S2), where S1 is a shaded area of a melting peak of the porous stretched PTFE tube before heat treatment, S2 is a shaded area of a melting peak of the porous stretched PTFE tube after heat setting, and S3 is a shaded area of a melting peak of the porous stretched PTFE tube after heat treatment.
Example 1
A manufacturing process of a porous PTFE stretched tube comprises the following steps:
1) oil mixing and curing: sieving PTFE dispersion resin DF-2046A with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 82:18 on a mixing device at a speed of 40r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, and performing constant-speed extrusion and drying at the speed of 5mm/min, wherein the cylinder temperature of the extruder is 60 ℃, the die temperature is 40 ℃, and the drying temperature is 200 ℃ to obtain a PTFE (polytetrafluoroethylene) extruded tube with the outer diameter of 5.5mm and the wall thickness of 0.5 mm;
4) and (3) heat treatment: carrying out heat treatment on the PTFE extruded pipe dried in the step 3) at 332 ℃ for 0.5min, wherein the crystallization conversion rate of the PTFE extruded pipe after the heat treatment is 0.40;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 240 ℃, wherein the stretching ratio is 5.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 390 ℃, and the heat setting time is 3min, so that the porous PTFE stretched tube with the outer diameter of 4.5mm and the wall thickness of 0.3mm is obtained.
Example 2
A manufacturing process of a porous PTFE stretched tube comprises the following steps:
1) oil mixing and curing: sieving PTFE dispersion resin DF-2046A with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 84:16 on a mixing device at a speed of 30r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, extruding and drying at a constant speed of 5mm/min, wherein the temperature of a cylinder of the extruder is 60 ℃, the temperature of a mouth mold is 40 ℃, and the drying temperature is 200 ℃ to obtain a PTFE (polytetrafluoroethylene) extruded tube with the outer diameter of 10.0mm and the wall thickness of 1.0 mm;
4) and (3) heat treatment: carrying out heat treatment on the dried PTFE extruded pipe in the step 3) at 334 ℃ for 1.0min, wherein the crystallization conversion rate of the heat-treated PTFE extruded pipe is 0.50;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 260 ℃, wherein the stretching ratio is 4.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 385 ℃, and the heat setting time is 5min, so that the porous PTFE stretched tube with the outer diameter of 9.2mm and the wall thickness of 0.6mm is obtained.
Example 3
A manufacturing process of a porous PTFE stretched tube comprises the following steps:
1) oil mixing and curing: sieving PTFE dispersion resin DF-203S with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 85:15 on a mixing device at a speed of 35r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, extruding at a constant speed and drying at the speed of 5mm/min, wherein the temperature of a cylinder of the extruder is 60 ℃, the temperature of a mouth mold is 40 ℃, and the drying temperature is 200 ℃ to obtain a PTFE (polytetrafluoroethylene) extruded tube with the outer diameter of 15.0mm and the wall thickness of 1.5 mm;
4) and (3) heat treatment: carrying out heat treatment on the dried PTFE extruded pipe in the step 3) at 338 ℃ for 2.0min, wherein the crystallization conversion rate of the heat-treated PTFE extruded pipe is 0.60;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 280 ℃, wherein the stretching ratio is 3.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 380 ℃, and the heat setting time is 10min, so that the porous PTFE stretched tube with the outer diameter of 14.5mm and the wall thickness of 1.1mm is obtained.
Comparative example 1
A manufacturing process of a porous PTFE stretched tube comprises the following steps:
1) oil mixing and curing: sieving PTFE dispersion resin DF-203S with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 85:15 on a mixing device at a speed of 30r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, and performing constant-speed extrusion and drying at the speed of 5mm/min, wherein the cylinder temperature of the extruder is 60 ℃, the die temperature is 40 ℃, and the drying temperature is 200 ℃ to obtain a PTFE (polytetrafluoroethylene) extruded tube with the outer diameter of 15.0mm and the wall thickness of 1.5 mm;
4) stretching: stretching the PTFE extruded pipe obtained in the step 3) at 280 ℃, wherein the stretching ratio is 3.0 times;
5) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 380 ℃, and the heat setting time is 10min, so as to obtain the porous PTFE stretched tube.
Comparative example 2
A manufacturing process of a porous PTFE stretched tube comprises the following steps:
1) oil mixing and curing: sieving PTFE dispersion resin DF-2046A with a 10-mesh sieve, mixing with isoparaffin adjuvant G at the mass ratio of 82:18 on a mixing device at the speed of 30r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, and performing constant-speed extrusion and drying at the speed of 5mm/min, wherein the cylinder temperature of the extruder is 60 ℃, the neck mold temperature is 40 ℃, and the drying temperature is 200 ℃ to obtain a PTFE (polytetrafluoroethylene) extruded tube with the outer diameter of 5.5mm and the wall thickness of 0.5 mm;
4) and (3) heat treatment: carrying out heat treatment on the PTFE extruded pipe dried in the step 3) at 370 ℃ for 5.0min, wherein the crystallization conversion rate of the PTFE extruded pipe after the heat treatment is 1.0;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 250 ℃, wherein the stretching ratio is 2.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 390 ℃, and the heat setting time is 3min, so that the porous PTFE stretched tube with the outer diameter of 5.0mm and the wall thickness of 0.4mm is obtained.
Comparative example 3
A process for producing a porous stretched PTFE tube using the heat treatment conditions and stretching conditions of sample 2# of example 1 disclosed in reference CN102961976A, comprising the steps of:
1) oil mixing and curing: sieving PTFE dispersion resin DF-2046A with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 84:16 on a mixing device at a speed of 30r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, and performing constant-speed extrusion and drying at the speed of 5mm/min, wherein the cylinder temperature of the extruder is 60 ℃, and the die temperature is 40 ℃, so as to obtain a PTFE (polytetrafluoroethylene) extruded pipe with the outer diameter of 10.0mm and the wall thickness of 1.0 mm;
4) and (3) heat treatment: carrying out heat treatment on the dried PTFE extruded pipe in the step 3) at 300 ℃ for 120min, wherein the crystallization conversion rate of the heat-treated PTFE extruded pipe is 0;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 100 ℃, wherein the stretching ratio is 3.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 385 ℃, and the heat setting time is 5min, so as to obtain the porous PTFE stretched tube.
Comparative example 4
A process for producing a porous stretched PTFE tube using the heat treatment conditions and stretching conditions of example 5 disclosed in the comparison document CN102961976A, comprising the steps of:
1) oil mixing and curing: sieving PTFE dispersion resin DF-2046A with a 10-mesh sieve, mixing with isoparaffin adjuvant G at a mass ratio of 82:18 on a mixing device at a speed of 40r/min for 30min, and standing at 25 deg.C for 24h for aging;
2) preforming: performing the cured PTFE dispersion resin at the speed of 30mm/min under the pressure of 2.5MPa for 30 min;
3) extruding and drying: moving the preformed blank to a pasty extruder, and performing constant-speed extrusion and drying at the speed of 5mm/min, wherein the cylinder temperature of the extruder is 60 ℃, and the die temperature is 40 ℃, so as to obtain a PTFE (polytetrafluoroethylene) extruded pipe with the outer diameter of 5.5mm and the wall thickness of 0.5 mm;
4) and (3) heat treatment: carrying out heat treatment on the PTFE extruded pipe dried in the step 3) at 380 ℃ for 0.5min, wherein the crystallization conversion rate of the PTFE extruded pipe after the heat treatment is 0.9;
5) stretching: stretching the PTFE extruded tube subjected to the heat treatment in the step 4) at 50 ℃, wherein the stretching ratio is 6.0 times;
6) heat setting: and (3) carrying out heat setting on the stretched PTFE extruded tube under tension, wherein the heat setting temperature is 390 ℃, and the heat setting time is 3min, so that the porous PTFE stretched tube with the outer diameter of 4.4mm and the wall thickness of 0.3mm is obtained.
The tensile conditions and tensile indexes of the porous stretched PTFE tubes obtained in examples 1 to 3 of the present invention and comparative examples 1 to 4 were measured, and the results are shown in table 1.
TABLE 1 test data for porous PTFE stretched tubes of examples 1-3 and comparative examples 1-4
| Example 1 | Example 2 | Example 3 | Comparative example 1 | Comparative example 2 | Comparative example 3 | Comparative example 4 | |
| Outside diameter of extruded tube, mm | 5.5 | 10.0 | 15.0 | 15.0 | 5.5 | 10.0 | 5.5 |
| Thickness of extruded tube wall, mm | 0.5 | 1.0 | 1.5 | 1.5 | 0.5 | 1.0 | 0.5 |
| Heat treatment temperature of | 332 | 334 | 338 | / | 370 | 300 | 380 |
| Heat treatment time, min | 0.5 | 1.0 | 2.0 | / | 5.0 | 120 | 0.5 |
| Conversion rate of crystallization | 0.40 | 0.50 | 0.60 | 0 | 1.0 | 0 | 0.90 |
| Stretching temperature of | 240 | 260 | 280 | 280 | 250 | 100 | 50 |
| Draw ratio, times | 5.0 | 4.0 | 3.0 | 3.0 | 2.0 | 3.0 | 6.0 |
| Situation of tension | Good effect | Good effect | Good effect | Can not be stretched | Not good | Can not be stretched | Not good |
| Presence or absence of longitudinal cracking | Is free of | Is free of | Is free of | Severe longitudinal cracking | Is free of | Severe longitudinal cracking | Is free of |
| Outside diameter of the stretched tube, mm | 4.5 | 9.2 | 14.5 | - | 5.0 | - | 4.4 |
| Wall thickness of drawn tube, mm | 0.3 | 0.6 | 1.1 | - | 0.4 | - | 0.3 |
| Porosity% | 86 | 76 | 69 | - | 35 | - | 42 |
| Tensile strength, MPa | 52 | 45 | 43 | - | 35 | - | 38 |
| Elongation percentage of% | 118 | 80 | 130 | - | 150 | - | 180 |
As can be seen from table 1, the PTFE extruded tubes of examples 1-3 did not crack longitudinally when stretched, had a porosity of greater than 60%, and had a tensile strength of between 40 and 55MPa, because the PTFE extruded tubes of examples 1-3 had an increased surface strength after heat treatment prior to stretching, and did not crack when stretched due to the presence of stress. In contrast, comparative example 1, in which heat treatment was not performed before stretching, the surface strength of the tube was low, and the longitudinal orientation was greater than the transverse orientation, and longitudinal cracking occurred under the stress; comparative example 2 because the heat treatment temperature was too high, the time was too long, the crystallization conversion rate was 1.0, the PTFE extruded tube was completely sintered, and the PTFE stretched tube was too hard, resulting in difficulty in increasing the porosity during stretching; comparative example 3 heat treatment at 300 ℃ for 120min, the PTFE extruded tube was not stretched because the PTFE extruded tube did not melt at 300 ℃ for the initial melting temperature of PTFE and did not increase in hardness because the PTFE extruded tube did not melt for any longer period of time, although the heat treatment time was long; the heat treatment temperature of comparative example 4 was too high, resulting in too large a crystallization conversion rate, too large a PTFE extruded tube hardness, and too low a porosity after stretching. As can be seen from the above examples and comparative examples, the present invention controls the crystallization conversion rate of the extruded tube to be 0.20 to 0.70 by controlling the temperature and time of the heat treatment, and for the PTFE extruded tube having an outer diameter of more than 5.0mm and a wall thickness of 0.5 to 1.5mm, the problem of longitudinal cracking during stretching can be solved, and a porous PTFE stretched tube having a porosity of more than 60%, a tensile strength of 40 to 55MPa, and an elongation of 50 to 150% can be obtained.
The above examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. It is to be understood that one or more method steps recited herein are not exclusive of other method steps being present before or after the recited combining step or intervening method steps between those explicitly recited, and further that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Moreover, unless otherwise indicated, the numbering of the various method steps is only a convenient tool for identifying the various method steps, and does not limit the order of the method steps or the scope of the invention, and changes or modifications in the relative relationship thereof may be considered as the scope of the invention without substantially changing the technical content.
Claims (7)
1. A manufacturing process of a porous PTFE stretched pipe is characterized by comprising the following steps:
(1) mixing oil, preforming, extruding and drying PTFE dispersion resin to obtain a PTFE extruded tube with the outer diameter larger than 5.0 mm;
(2) carrying out heat treatment on the PTFE extruded pipe obtained in the step (1), wherein the heat treatment temperature is 331-338 ℃, and the heat treatment time is 0.5-2 min; the crystallization conversion rate after the heat treatment is 0.20-0.70;
(3) stretching the PTFE extruded tube subjected to the heat treatment in the step (2), wherein the stretching temperature is 220-290 ℃, and the stretching ratio is 1.0-5.0 times;
(4) and (4) carrying out heat setting on the stretched PTFE extruded pipe under tension to obtain the porous PTFE stretched pipe.
2. The process according to claim 1, wherein the extruded PTFE tube of step (1) has an outer diameter of 5.5 to 16.0mm and a wall thickness of 0.5 to 1.5 mm.
3. The manufacturing process according to claim 1, wherein the crystallization conversion rate after the heat treatment is 0.40 to 0.60.
4. The process according to claim 1, wherein the stretching temperature in the step (3) is 240 to 280 ℃ and the stretching ratio is 3 to 5.
5. The manufacturing process according to claim 1, wherein the heat setting temperature in the step (4) is 380 to 390 ℃ and the heat setting time is 1 to 10 min.
6. The porous stretched PTFE tube prepared by the manufacturing process according to claim 1, wherein the porous stretched PTFE tube has an outer diameter of 3.5 to 15.0mm, a wall thickness of 0.3 to 1.3mm, a porosity of 60 to 90%, a tensile strength of 40 to 55MPa, and an elongation of 50 to 150%.
7. Use of the porous PTFE stretched tube of claim 6 as a medical tube, a chemical tube, or a water treatment tube.
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| CN102961976A (en) * | 2012-12-14 | 2013-03-13 | 国家***天津海水淡化与综合利用研究所 | Polytetrafluoroethylene hollow fiber micro-porous film and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102961976A (en) * | 2012-12-14 | 2013-03-13 | 国家***天津海水淡化与综合利用研究所 | Polytetrafluoroethylene hollow fiber micro-porous film and preparation method thereof |
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