CN113005545A - Preparation method of polytetrafluoroethylene ultra-fine filament - Google Patents
Preparation method of polytetrafluoroethylene ultra-fine filament Download PDFInfo
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- CN113005545A CN113005545A CN202110256940.7A CN202110256940A CN113005545A CN 113005545 A CN113005545 A CN 113005545A CN 202110256940 A CN202110256940 A CN 202110256940A CN 113005545 A CN113005545 A CN 113005545A
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- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 139
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 139
- -1 polytetrafluoroethylene Polymers 0.000 title claims abstract description 138
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 38
- 238000010438 heat treatment Methods 0.000 claims abstract description 35
- 239000000203 mixture Substances 0.000 claims abstract description 35
- 239000002245 particle Substances 0.000 claims abstract description 27
- 238000001816 cooling Methods 0.000 claims abstract description 18
- 238000000748 compression moulding Methods 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 15
- 230000006835 compression Effects 0.000 claims abstract description 14
- 238000007906 compression Methods 0.000 claims abstract description 14
- 238000004804 winding Methods 0.000 claims abstract description 13
- 238000007493 shaping process Methods 0.000 claims abstract description 10
- 238000005520 cutting process Methods 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 31
- 239000008187 granular material Substances 0.000 claims description 21
- 238000007873 sieving Methods 0.000 claims description 16
- 238000005096 rolling process Methods 0.000 claims description 11
- 238000003825 pressing Methods 0.000 claims description 10
- 238000007789 sealing Methods 0.000 claims description 6
- 238000012216 screening Methods 0.000 claims description 4
- 239000000835 fiber Substances 0.000 abstract description 16
- 239000003921 oil Substances 0.000 description 37
- 230000000052 comparative effect Effects 0.000 description 9
- 238000009987 spinning Methods 0.000 description 8
- 239000000839 emulsion Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 4
- 229920001410 Microfiber Polymers 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000003658 microfiber Substances 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000003209 petroleum derivative Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003490 calendering Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 238000009998 heat setting Methods 0.000 description 1
- 238000002074 melt spinning Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000002166 wet spinning Methods 0.000 description 1
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/42—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments
- D01D5/426—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments by cutting films
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/08—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of halogenated hydrocarbons
- D01F6/12—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of halogenated hydrocarbons from polymers of fluorinated hydrocarbons
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01H—SPINNING OR TWISTING
- D01H7/00—Spinning or twisting arrangements
- D01H7/02—Spinning or twisting arrangements for imparting permanent twist
- D01H7/86—Multiple-twist arrangements, e.g. two-for-one twisting devices ; Threading of yarn; Devices in hollow spindles for imparting false twist
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
- Artificial Filaments (AREA)
Abstract
The invention belongs to the technical field of preparation of polytetrafluoroethylene fibers, and particularly relates to a preparation method of a polytetrafluoroethylene ultra-thin filament. Treating the polytetrafluoroethylene dispersed particles at low temperature, mixing with the auxiliary oil, curing, and carrying out compression molding; placing the polytetrafluoroethylene mixture in a pushing mold cavity with a compression ratio of 260 to push and continuously extrude strips to obtain polytetrafluoroethylene material strips; extruding a polytetrafluoroethylene material strip into a film, and removing oil through heat treatment; stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film; longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments. The polytetrafluoroethylene ultra-thin filament prepared by the preparation method has the advantages of high strength, uniform linear density, no burr and low shrinkage rate.
Description
Technical Field
The invention belongs to the technical field of preparation of polytetrafluoroethylene fibers, and particularly relates to a preparation method of a polytetrafluoroethylene ultra-thin filament.
Background
Polytetrafluoroethylene is not suitable for fiber formation by conventional solution spinning and melt spinning due to its structural specificity. The production methods common to polytetrafluoroethylene fibers to date include three types: emulsion spinning, paste extrusion method and splitting method.
(1) The emulsion spinning, also called carrier spinning, is the most mature method for producing polytetrafluoroethylene fiber at present, usually use viscose or polyvinyl alcohol aqueous solution easy to form fiber as carrier, mix with polytetrafluoroethylene emulsion, carry on spinning according to the conventional wet spinning method, form fiber and sinter under 380 and 400 duC high temperature after washing and drying, thus remove the carrier part, and then carry on the appropriate extension under 350 duC to the polytetrafluoroethylene that has already bonded under high temperature, get finished polytetrafluoroethylene fiber. This process is generally carried out by spinning the solution through a spinneret.
(2) Paste extrusion method: mixing polytetrafluoroethylene dispersion resin powder with petroleum products easy to volatilize (as lubricating oil), preparing into paste, placing into an extruder, pressing into flat or round filaments through a die, drying, volatilizing the lubricating agent, and stretching to obtain the finished product.
(3) And (3) a splitting method: mixing polytetrafluoroethylene dispersion resin powder and petroleum products easy to volatilize together (as lubricating oil), preparing into paste, putting into an extruder, pressing into bars or sheets through a die, rolling the bars into sheets, drying, volatilizing the lubricating agent, stretching, cutting into narrow strips with certain width through a blade, and finally stretching to obtain finished products, wherein some products need twisting treatment.
Generally, emulsion spinning can only process short fibers, and the strength is low, and the section of the short fibers is changed according to the hole shape of a spinneret; only long filaments can be processed by paste extrusion, the strength is low, and the cross section of the long filaments is changed according to the hole shape of the neck ring mold; the splitting method can process filament and staple, the strength of the fiber is generally higher than that of emulsion spinning and paste extrusion, and the section of the filament and the staple is generally flat due to the adoption of blade segmentation.
For the preparation of the superfine polytetrafluoroethylene fiber with the length of more than or equal to 5000 meters, no good method exists at present, the preparation by adopting the method is difficult to ensure the uniformity of the length and the linear density of the polytetrafluoroethylene fiber, and the yarn breakage is easy to occur; when the high tensile strength is achieved, the polytetrafluoroethylene fiber is easy to fluff and stab, and the index of the elongation at break is difficult to reach the standard while the low shrinkage rate is ensured.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: providing a preparation method of a polytetrafluoroethylene ultra-thin filament; the polytetrafluoroethylene superfine filament prepared by the method has the advantages of high strength, uniform linear density, no burr, low shrinkage rate and low yarn evenness.
The preparation method of the polytetrafluoroethylene ultra-thin filament comprises the following steps:
(1) storing the polytetrafluoroethylene dispersed granules in a low-temperature environment for a period of time, sieving the granules, mixing the sieved granules with auxiliary oil in proportion to obtain a polytetrafluoroethylene mixture treated by the low-temperature oil, sieving the mixture again, and sealing the sieved mixture for later use;
(2) curing the polytetrafluoroethylene mixture prepared in the step (1) in a high-temperature environment, and then carrying out compression molding;
(3) putting the polytetrafluoroethylene mixture subjected to compression molding in the step (2) into a pressing mold cavity with a compression ratio of 260 to press and continuously extrude strips to obtain polytetrafluoroethylene material strips;
(4) feeding the polytetrafluoroethylene material strips into a calender through a guide plate to extrude a film, and carrying out heat treatment on the film to remove oil;
(5) stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film with the width of 12-15 cm;
(6) longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments.
Wherein:
storing the polytetrafluoroethylene dispersed granules in the step (1) at a low temperature of 0-10 ℃ for 45-50h, preferably at a low temperature of 0-5 ℃ for 48 h; the particle size of the polytetrafluoroethylene dispersed particle material is controlled to be 450-600 microns through material screening, and then the polytetrafluoroethylene dispersed particle material is mixed with the auxiliary oil.
The auxiliary oil in the step (1) is white oil; the mixing mass ratio of the polytetrafluoroethylene particle material to the auxiliary oil is 1: 0.3-0.35.
And (2) sieving the polytetrafluoroethylene mixture treated by the low-temperature oil in the step (1) again, and controlling the particle size to be 450-600 microns.
And (3) standing at the high temperature of 55-58 ℃ for 24-48h for curing in the step (2).
The compression molding pressure in the step (2) is 4.5-5Kg/cm2The temperature is 28-32 deg.C, and the time is 4-5 min.
The speed of extruding the strips in the step (3) is 18-20 m/min.
The temperature of the roller during the rolling in the step (4) is 60-65 ℃, and the linear speed of the rolling is 10-15 m/min.
The heat treatment temperature in the step (4) is 180-220 ℃.
The thickness of the polytetrafluoroethylene film in the step (5) is 0.12-0.15 mm.
The multi-time stretching in the step (5) is longitudinal stretching through multiple rollers, the total stretching multiple is 4-5 times, the heating temperature is 340-350 ℃, 5 rollers are arranged, the stretching multiple of each roller is different, and the stretching multiple of each roller is 1.25 times, 1.23 times, 1.2-1.3 times, 1.5 times and 1.45-1.8 times in sequence. The stretching ratio of the next roller is set on the basis of the completion of the stretching of the previous roller.
The temperature of the heating and stretching in the step (6) is 397-403 ℃, and the longitudinal stretching multiple is 15-16 times.
The number of the flat wires in the step (6) is 60-70.
The temperature of the rapid cooling in the step (6) is less than or equal to 30 ℃, and the cooling time is 1-2 s.
The total twisting number in the step (6) is 800-; the temperature for heating and setting is 350-380 ℃.
In the stretching process, the material forms the microfibers, the microfibers have high strength, so that the PTFE can be self-reinforced, the stretching rate is low during treatment, certain repairing effect is realized on defects in the material, the microfiber content in the material is increased along with the increase of the stretching length, and the overall strength is improved.
Preferably, the preparation method of the polytetrafluoroethylene ultra-fine filament comprises the following steps:
(1) placing the polytetrafluoroethylene dispersed granular material in a low-temperature environment of 0-10 ℃ for 48 hours, and uniformly mixing the polytetrafluoroethylene dispersed granular material with auxiliary oil according to the proportion of 1:0.3 by a sieve material to obtain a polytetrafluoroethylene mixture treated by low-temperature oil; and sieving the materials again, then placing the materials in a plastic barrel, and sealing the plastic barrel.
(2) Placing the mixed materials in a high-temperature environment at the temperature of 55-58 ℃ for aging for 24-48 hours.
(3) And (3) putting the polytetrafluoroethylene mixture cured in the step (2) into a mould, and applying pressure for forming.
(4) And (4) placing the polytetrafluoroethylene mixture subjected to compression molding in the step (3) in a pressing mold cavity with the compression ratio of 260 to press and continuously extrude the strips, wherein the strips are prevented from being damaged.
(5) And (4) feeding the material strips extruded in the step (4) into a calender through a guide plate to extrude a film, wherein the roller temperature is 60 ℃, and the calendering speed is 15 m/min.
(6) And (4) performing heat treatment on the film subjected to the step (5) to remove oil, wherein the temperature of the oil removal process is 200-220 ℃.
(7) And (4) stretching the film subjected to oil removal in the step (6) in multiple steps, wherein the stretching multiple is 4-5 times, and obtaining the film with the width of about 12 centimeters.
(8) And (4) cutting the film subjected to the step (7) into a plurality of flat wires, and heating and stretching the flat wires in an oven, wherein the temperature of the oven is 397-.
(9) And (4) preparing the silk subjected to the step (8) into round silk in a twisting mode, and rapidly cooling while twisting and shaping to stabilize the thermal shrinkage and the elongation at break of the silk.
(10) And (4) winding the silk subjected to the step (9) on a shaft through a bobbin.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the preparation method of the polytetrafluoroethylene ultra-thin filament, the compression ratio is increased from 180 recorded in the prior art to 260 recorded in the prior art by increasing the compression ratio, so that the tensile strength of the fiber is improved; the width and the thickness of the base film are changed to lay a foundation for the next process, and too wide width of the film can cause too many filaments and the filaments are easy to break in an oven; the twisting mode is changed, the double twisting mode is adopted to ensure that the twist of the fiber is uniform, and the untwisting phenomenon does not occur; by changing the heat setting mode and matching with rapid heating and cooling, the monofilament is set to achieve low heat shrinkage and stable elongation at break.
(2) According to the preparation method of the polytetrafluoroethylene ultra-thin filament, if the width of the obtained polytetrafluoroethylene film is reduced, the number of filaments is reduced, and the efficiency is affected; if the width of the obtained polytetrafluoroethylene film is increased, the filament with the length of 6000-10000 meters cannot be prepared; when the rapid cooling operation in the step (6) is not performed, the elongation at break of the obtained superfine filament is not uniform; if the double twisting mode is not adopted in the step (6), the phenomenon of untwisting occurs in the preparation process, and the untwisted part causes uneven thickness of the superfine filaments because of insufficient twist.
(3) The length of the polytetrafluoroethylene ultra-thin filament prepared by the preparation method is 6000-10000 m, the linear density is less than or equal to 90denier, the breaking strength is more than 5.0gf/denier, the elongation at break is less than or equal to 5 percent, the shrinkage rate is less than or equal to 1 percent, the evenness is 2-3 percent, no burr phenomenon exists, the filament breakage rate is poor, and all indexes are in the required range.
Drawings
FIG. 1 is a flow chart of a preparation process of a polytetrafluoroethylene ultra-thin filament.
Detailed Description
The present invention is further described below with reference to examples.
Example 1
The preparation method of the polytetrafluoroethylene ultra-fine filament described in this embodiment 1 comprises the following steps:
(1) storing the polytetrafluoroethylene dispersed granules in a low-temperature environment for a period of time, sieving the granules, mixing the sieved granules with auxiliary oil in proportion to obtain a polytetrafluoroethylene mixture treated by the low-temperature oil, sieving the mixture again, and sealing the sieved mixture for later use;
(2) curing the polytetrafluoroethylene mixture prepared in the step (1) in a high-temperature environment, and then carrying out compression molding;
(3) putting the polytetrafluoroethylene mixture subjected to compression molding in the step (2) into a pressing mold cavity with a compression ratio of 260 to press and continuously extrude strips to obtain polytetrafluoroethylene material strips;
(4) feeding the polytetrafluoroethylene material strips into a calender through a guide plate to extrude a film, and carrying out heat treatment on the film to remove oil;
(5) stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film with the width of 15 cm;
(6) longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments.
Wherein:
and (2) storing the polytetrafluoroethylene dispersed particles in the step (1) for 48 hours at a low temperature of 5 ℃, controlling the particle size of the polytetrafluoroethylene dispersed particles to be 450-600 microns, and then mixing the polytetrafluoroethylene dispersed particles with auxiliary oil.
The auxiliary oil in the step (1) is white oil; the mixing mass ratio of the polytetrafluoroethylene particle material to the auxiliary oil is 1: 0.30.
And (2) sieving the polytetrafluoroethylene mixture treated by the low-temperature oil in the step (1) again, and controlling the particle size to be 450-600 microns.
And (3) standing at the high temperature of 55 ℃ for 35h for curing in the step (2).
The compression molding pressure in the step (2) is 5Kg/cm2The temperature is 30 ℃ and the time is 5 min.
The speed of extruding the sliver in the step (3) is 20 m/min.
And (4) during rolling, the temperature of the roller is 65 ℃, and the linear speed of the rolling is 15 m/min.
The heat treatment temperature in the step (4) is 220 ℃.
The thickness of the polytetrafluoroethylene film in the step (5) is 0.15 mm.
The multiple stretching in the step (5) is performed by multiple rollers, the stretching multiple is 4 times, the heating temperature is 350 ℃, 5 rollers are arranged, the stretching multiple of each roller is different, and the stretching multiple of each roller is 1.25 times, 1.23 times, 1.2 times, 1.5 times and 1.45 times in sequence.
The heating and stretching temperature in the step (6) is 400 ℃, and the stretching multiple is 15 times.
And (4) rapidly cooling at 25 ℃ for 2s in the step (6).
The number of the flat wires in the step (6) is 70.
The total twisting number in the step (6) is 850 twists/m, and the temperature for heating and shaping is 380 ℃.
The polytetrafluoroethylene ultra-thin filament prepared by the process of example 1 has the length of 6000 meters, the linear density of 90denier, the breaking strength of 5.5N, the elongation at break of 4.2%, the shrinkage of 0.50%, the yarn evenness of 2%, no burr phenomenon, poor yarn breakage rate and all indexes within the required range.
Example 2
The preparation method of the polytetrafluoroethylene ultra-fine filament described in the embodiment 2 comprises the following steps:
(1) storing the polytetrafluoroethylene dispersed granules in a low-temperature environment for a period of time, sieving the granules, mixing the sieved granules with auxiliary oil in proportion to obtain a polytetrafluoroethylene mixture treated by the low-temperature oil, sieving the mixture again, and sealing the sieved mixture for later use;
(2) curing the polytetrafluoroethylene mixture prepared in the step (1) in a high-temperature environment, and then carrying out compression molding;
(3) putting the polytetrafluoroethylene mixture subjected to compression molding in the step (2) into a pressing mold cavity with a compression ratio of 260 to press and continuously extrude strips to obtain polytetrafluoroethylene material strips;
(4) feeding the polytetrafluoroethylene material strips into a calender through a guide plate to extrude a film, and carrying out heat treatment on the film to remove oil;
(5) stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film with the width of 14 cm;
(6) longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments.
Wherein:
storing the polytetrafluoroethylene dispersed granules in the step (1) for 45 hours at a low temperature of 0 ℃; the particle size of the polytetrafluoroethylene dispersed particle material is controlled to be 450-600 microns through material screening, and then the polytetrafluoroethylene dispersed particle material is mixed with the auxiliary oil.
The auxiliary oil in the step (1) is white oil; the mixing mass ratio of the polytetrafluoroethylene particle material to the auxiliary oil is 1: 0.31.
And (2) sieving the polytetrafluoroethylene mixture treated by the low-temperature oil in the step (1) again, and controlling the particle size to be 450-600 microns.
And (3) standing at the high temperature of 58 ℃ for 30h for curing in the step (2).
The compression molding pressure in the step (2) is 4.5Kg/cm2The temperature is 32 ℃ and the time is 5 min.
The speed of extruding the sliver in the step (3) is 19 m/min.
And (4) during rolling, the temperature of the roller is 63 ℃, and the linear speed of the rolling is 13 m/min.
The heat treatment temperature in the step (4) is 200 ℃.
The thickness of the polytetrafluoroethylene film in the step (5) is 0.14 mm.
The multiple stretching in the step (5) is to perform stretching through multiple rollers, the stretching multiple is 4.5 times, the heating temperature is 345 ℃, 5 rollers are arranged totally, the stretching multiple of each roller is different, and the stretching multiple of each roller is 1.25 times, 1.23 times, 1.2 times, 1.5 times and 1.62 times in sequence.
The heating and stretching temperature in the step (6) is 400 ℃, and the stretching multiple is 16 times.
The number of the flat wires in the step (6) is 65.
The temperature of the rapid cooling in the step (6) is 24 ℃, and the cooling time is 2 s.
The total twisting number in the step (6) is 890 twists/m, and the temperature for heating and shaping is 370 ℃.
The polytetrafluoroethylene ultra-thin filament prepared by the process of the embodiment 2 has the length of 8000 meters, the linear density of 90denier, the breaking strength of 5.3N, the elongation at break of 4.8 percent, the shrinkage of 0.7 percent, the yarn evenness of 2.5 percent, no burr phenomenon, poor yarn breakage rate and all indexes within the required range.
Example 3
The preparation method of the polytetrafluoroethylene ultra-fine filament described in this embodiment 3 comprises the following steps:
(1) storing the polytetrafluoroethylene dispersed granules in a low-temperature environment for a period of time, sieving the granules, mixing the sieved granules with auxiliary oil in proportion to obtain a polytetrafluoroethylene mixture treated by the low-temperature oil, sieving the mixture again, and sealing the sieved mixture for later use;
(2) curing the polytetrafluoroethylene mixture prepared in the step (1) in a high-temperature environment, and then carrying out compression molding;
(3) putting the polytetrafluoroethylene mixture subjected to compression molding in the step (2) into a pressing mold cavity with a compression ratio of 260 to press and continuously extrude strips to obtain polytetrafluoroethylene material strips;
(4) feeding the polytetrafluoroethylene material strips into a calender through a guide plate to extrude a film, and carrying out heat treatment on the film to remove oil;
(5) stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film with the width of 12 cm;
(6) longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments.
Wherein:
storing the polytetrafluoroethylene dispersed granules in the step (1) for 48 hours at a low temperature of 3 ℃; the particle size of the polytetrafluoroethylene dispersed particle material is controlled to be 450-600 microns through material screening, and then the polytetrafluoroethylene dispersed particle material is mixed with the auxiliary oil.
The auxiliary oil in the step (1) is white oil; the mixing mass ratio of the polytetrafluoroethylene particle material to the auxiliary oil is 1: 0.35.
And (2) sieving the polytetrafluoroethylene mixture treated by the low-temperature oil in the step (1) again, and controlling the particle size to be 450-600 microns.
And (3) standing at the high temperature of 55 ℃ for 42h for curing in the step (2).
The compression molding pressure in the step (2) is 4.7Kg/cm2The temperature is 28 ℃ and the time is 5 min.
The speed of extruding the sliver in the step (3) is 18 m/min.
And (4) during rolling, the temperature of the roller is 60 ℃, and the linear speed of the rolling is 10 m/min.
The heat treatment temperature in the step (4) is 180 ℃.
The thickness of the polytetrafluoroethylene film in the step (5) is 0.12 mm.
The multiple stretching in the step (5) is performed by multiple rollers, the stretching multiple is 5 times, the heating temperature is 340 ℃, 5 rollers are arranged, the stretching multiple of each roller is different, and the stretching multiple of each roller is 1.25 times, 1.23 times, 1.2 times, 1.5 times and 1.8 times in sequence.
The temperature of the heating and stretching in the step (6) is 397 ℃, and the stretching ratio is 16 times.
The number of the flat wires in the step (6) is 60.
The temperature of the rapid cooling in the step (6) is 27 ℃, and the cooling time is 2 s.
The total twisting number in the step (6) is 1000 twists/m, and the temperature for heating and shaping is 360 ℃.
The polytetrafluoroethylene ultra-thin filament prepared by the process of the embodiment 3 has the length of 8000 meters, the linear density of 85denier, the breaking strength of 5.1N, the elongation at break of 4.3 percent, the shrinkage of 0.92 percent, the yarn evenness of 2.2 percent, no burr phenomenon, poor yarn breakage rate and all indexes within the required range.
Comparative example 1
The method for preparing a polytetrafluoroethylene ultra-fine filament according to comparative example 1 is the same as that of example 1, except that the compression ratio in step (3) is different, and the compression ratio in the pressing die cavity in step (3) is 180.
The length of the polytetrafluoroethylene ultra-thin filament prepared by the process of the comparative example 1 is 4100 meters, and through detection, the change of other parameters is small, but the breaking strength is 3.3N, which is reduced by 40 percent compared with the example 1.
Comparative example 2
The method for preparing the polytetrafluoroethylene ultra-thin filament in the comparative example 2 is the same as that in the example 1, and has the only difference that the compression ratio in the step (3) is different, the compression ratio in the pushing mold cavity in the step (3) is 280, the polytetrafluoroethylene material strip obtained in the step (3) is very hard due to the increase of the compression ratio, so that the membrane and the filament are broken, the length of the prepared polytetrafluoroethylene ultra-thin filament is only 1000 meters, the breaking strength is 5.5N, the unevenness of the strip is 10 percent, the burrs are particularly serious, and the length and the quality do not reach the standard.
Comparative example 3
The method for preparing a polytetrafluoroethylene ultra-fine filament according to comparative example 3 is the same as that of example 1, except that the stretching ratio in step (5) is 9 times and the stretching ratio in step (6) is 4 times. Since the draw ratio was too large, the unevenness on both sides of the film was increased, and the drawn yarn density was not uniform, the CV value was 8.5%.
Comparative example 4
The method for preparing the polytetrafluoroethylene ultra-thin filament in the comparative example 4 is the same as that in the example 1, and the only difference is that a double twisting mode is not adopted in the step (6), the phenomena of uneven twist and untwisting occur in the preparation process, the untwisted part causes uneven thickness of the ultra-thin filament due to insufficient twist, and the change of other parameters is not large through detection, but the yarn evenness unevenness rate is 11%.
Claims (10)
1. A preparation method of polytetrafluoroethylene ultra-thin filament is characterized by comprising the following steps: the method comprises the following steps:
(1) storing the polytetrafluoroethylene dispersed granules in a low-temperature environment for a period of time, sieving the granules, mixing the sieved granules with auxiliary oil in proportion to obtain a polytetrafluoroethylene mixture treated by the low-temperature oil, sieving the mixture again, and sealing the sieved mixture for later use;
(2) curing the polytetrafluoroethylene mixture prepared in the step (1) in a high-temperature environment, and then carrying out compression molding;
(3) putting the polytetrafluoroethylene mixture subjected to compression molding in the step (2) into a pressing mold cavity with a compression ratio of 260 to press and continuously extrude strips to obtain polytetrafluoroethylene material strips;
(4) feeding the polytetrafluoroethylene material strips into a calender through a guide plate to extrude a film, and carrying out heat treatment on the film to remove oil;
(5) stretching the deoiled film for multiple times to obtain a polytetrafluoroethylene film with the width of 12-15 cm;
(6) longitudinally cutting the polytetrafluoroethylene film into a plurality of flat filaments, heating and stretching, preparing the obtained filaments into round filaments by a double twisting mode, twisting and shaping, simultaneously rapidly cooling, and finally winding the filaments on a shaft by a winding machine to obtain the polytetrafluoroethylene ultra-thin filaments.
2. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: storing the polytetrafluoroethylene dispersed granules in the step (1) for 45-50h at a low temperature of 0-10 ℃; the particle size of the polytetrafluoroethylene dispersed particle material is controlled to be 450-600 microns through material screening, and then the polytetrafluoroethylene dispersed particle material is mixed with the auxiliary oil.
3. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the auxiliary oil in the step (1) is white oil; the mixing mass ratio of the polytetrafluoroethylene particle material to the auxiliary oil is 1: 0.3-0.35.
4. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: and (2) sieving the polytetrafluoroethylene mixture treated by the low-temperature oil in the step (1) again, and controlling the particle size to be 450-600 microns.
5. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: standing at 55-58 ℃ for 24-48h for curing in the step (2);
the compression molding pressure in the step (2) is 4.5-5Kg/cm2The temperature is 28-32 deg.C, and the time is 4-5 min.
6. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the speed of extruding the strips in the step (3) is 18-20 m/min.
7. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the temperature of the roller during the rolling in the step (4) is 60-65 ℃, and the linear speed of the rolling is 10-15 m/min; the heat treatment temperature is 180-220 ℃.
8. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the thickness of the polytetrafluoroethylene film in the step (5) is 0.12-0.15 mm;
the multi-time stretching in the step (5) is longitudinal stretching through multiple rollers, the total stretching multiple is 4-5 times, the heating temperature is 340-350 ℃, 5 rollers are arranged, the stretching multiple of each roller is different, and the stretching multiple of each roller is 1.25 times, 1.23 times, 1.2-1.3 times, 1.5 times and 1.45-1.8 times in sequence.
9. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the heating and stretching temperature in the step (6) is 397-403 ℃, and the longitudinal stretching multiple is 15-16 times; the number of the flat wires is 60-70.
10. The method for preparing a polytetrafluoroethylene ultra-fine filament according to claim 1, wherein: the temperature of the rapid cooling in the step (6) is less than or equal to 30 ℃, and the cooling time is 1-2 s; the total twisting number is 800-; the temperature for heating and setting is 350-380 ℃.
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| CN115058784A (en) * | 2022-06-24 | 2022-09-16 | 灵氟隆新材料科技江苏有限公司 | Preparation method of polytetrafluoroethylene flat filament with high mass density uniformity |
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