CN107805850B - High-strength high-modulus polyformaldehyde fiber and preparation method thereof - Google Patents
High-strength high-modulus polyformaldehyde fiber and preparation method thereof Download PDFInfo
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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
- D01D5/08—Melt spinning methods
- D01D5/088—Cooling filaments, threads or the like, leaving the spinnerettes
- D01D5/0885—Cooling filaments, threads or the like, leaving the spinnerettes by means of a liquid
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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
- D01D5/08—Melt spinning methods
- D01D5/096—Humidity control, or oiling, of filaments, threads or the like, leaving the spinnerettes
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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
- D01D5/12—Stretch-spinning methods
- D01D5/16—Stretch-spinning methods using rollers, or like mechanical devices, e.g. snubbing pins
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- 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
- D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
- D01F6/76—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from other polycondensation products
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Abstract
The invention relates to a high-strength high-modulus polyformaldehyde fiber and a preparation method thereof, wherein the preparation method comprises the following steps: and extruding the polyformaldehyde melt from a spinneret, cooling in air and refrigerating fluid in sequence to obtain filaments, and performing high-power stretching treatment on the filaments to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the refrigerating fluid is a high-boiling-point alcohol aqueous solution with the temperature of less than or equal to 0 ℃. The tensile strength of the high-strength high-modulus polyformaldehyde fiber prepared by the method is more than or equal to 6.5cN/dtex, and the tensile modulus is more than or equal to 130 cN/dtex. The high-strength high-modulus polyformaldehyde fiber and the preparation method thereof have the advantages of simplicity and convenience in operation, high efficiency, low failure rate in the spinning process, easiness in realization of industrial production, few structural defects of the finally prepared polyformaldehyde fiber, high tensile strength and tensile modulus, excellent mechanical property, stable quality, and extremely high economic value and popularization value.
Description
Technical Field
The invention belongs to the field of chemical fiber manufacturing, and relates to a high-strength high-modulus polyformaldehyde fiber and a preparation method thereof.
Background
Polyformaldehyde is a linear polymer with a regular molecular structure, high density and high crystallinity, has good physical and mechanical properties and chemical resistance, can be used for a long time at the temperature of-40-100 ℃, is one of three general engineering plastics in the world at present, and is called steel-depriving and super steel-requiring.
The polyformaldehyde can inherit most advantages of polyformaldehyde after being spun into fibers and can exert potential advantages of polyformaldehyde, and the polyformaldehyde not only has high strength and high modulus, but also has excellent performances such as dimensional stability, thermal stability, alkali resistance, chemical corrosion resistance, light resistance, weather resistance, wear resistance and the like, is one of synthetic fibers with the best comprehensive performance, and has a good application prospect.
The high strength and high modulus of the polyoxymethylene fiber are mainly due to high-power drawing of the polyoxymethylene fiber. The crystallization degree of the polyformaldehyde homopolymer with a regular molecular structure is up to 70% or above, the crystallization speed is very high, when fibers are stretched, polyformaldehyde is converted from folded chain lamella crystals to extended chain crystal series, at the moment, slippage among the lamellas is easy to occur, cracks are formed on the surfaces of the fibers, and simultaneously, a large number of micropores are generated in the fibers, so that the stretching difficulty is caused, and the quality of the fibers is deteriorated. Early on, special drawing techniques were used to produce polyoxymethylene fibers, for example, in 1974 Clark, tennessee university, usa, in a hot air atmosphere, and high modulus polyoxymethylene fibers were tried by two steps of slow drawing polyoxymethylene bars 20 times in a tensile tester. The technical research institute of the Asahi chemical industry Co., Ltd in Japan at the beginning of the last 90 th century developed the drawing of a polymer material under a condition of heating under high pressure to obtain a high-strength fiber. However, the methods have complex equipment, large operation difficulty and low practical value.
In recent years, research on polyoxymethylene fibers focuses on the control of polyoxymethylene crystals in the fiber forming process, and the main technical means include blending modification and copolymerization modification, wherein the former is that a substance capable of reducing the spherulite size and the crystallization rate of polyoxymethylene is added into polyoxymethylene; the latter is that other structural units are introduced into the molecular chain of polyformaldehyde, so that the regularity of the molecular chain is destroyed and the crystallization rate of the molecular chain is slowed down.
The patent with application number 201510955587.6 discloses that polyformaldehyde fibers are obtained by mixing polyformaldehyde with one or more internal lubricants of fatty acid esters, fatty alcohols, fatty amides or low molecular weight hydrocarbons, extruding, granulating, drying and melt spinning; the used internal lubricant can improve the fluidity of the polyformaldehyde melt and slow down the crystallization of the polyformaldehyde melt; the patent with the application number of 201510703758.6 discloses that polyformaldehyde resin and sorbitol substances are mixed and dried for melt spinning, sprayed melt is blown with hot air to be slowly cooled, oiling and bundling are carried out, primary thermal drafting is carried out, primary fiber is obtained after winding, and the primary fiber is placed at room temperature to balance internal stress and then is subjected to multi-stage low-speed high-power drafting to obtain high-strength high-modulus polyformaldehyde fiber; sorbitol substances also act as crystallization inhibitors; patent application No. 02818234.0 discloses that the semi-crystallization time of a polyoxymethylene copolymer is 30 seconds or more when the polyoxymethylene copolymer is cooled from a molten state at 200 ℃ to 150 ℃ and is kept stable at a temperature of 150 ℃ by designing a polyoxymethylene copolymer suitable for melt spinning and introducing oxyalkylene-based repeating units into a polyoxymethylene molecular chain. The patent document also states that if a polymer having a semi-crystallization time of less than 30 seconds is used, a polyoxymethylene fiber having high strength and high rigidity cannot be obtained in a general fiber production apparatus, and efficient production cannot be performed. The blending modification method has the main problems that after the polyformaldehyde resin and the modifier are mixed, if the polyformaldehyde resin and the modifier are directly spun, the modifier is difficult to be uniformly dispersed in a polyformaldehyde melt with high viscosity; if the polyformaldehyde is extruded and granulated and then spun after mixing, because the melting point of the polyformaldehyde is close to the decomposition temperature, the polyformaldehyde is easily degraded by granulation, and the performance of the final fiber is influenced. The copolymerization modification method has high technical difficulty, does not have a mature and stable related technology at present in China, and is inconvenient for industrial popularization.
Therefore, the research on the preparation method which is simple and convenient to operate, high in efficiency and capable of effectively improving the mechanical property of the polyformaldehyde fiber is of great significance.
Disclosure of Invention
The invention aims to solve the problems of complex equipment, high operation difficulty and poor mechanical property of prepared polyformaldehyde fibers in the prior art, and provides the high-strength high-modulus polyformaldehyde fibers which are simple and convenient to operate and high in efficiency and can effectively improve the mechanical property of the fibers and the preparation method thereof. The invention relates to a melt spinning process, which adopts a high-boiling-point alcohol aqueous solution as a refrigerating fluid to improve the technical defects of the prior production of polyformaldehyde fibers, wherein the refrigerating fluid can cool a polyformaldehyde melt trickle extruded by a spinneret, effectively reduce the crystallinity of polyformaldehyde nascent fibers, play a role of a spinning oil agent and a lubricant, and facilitate the smooth high-power drafting of subsequent nascent fibers to obtain high-quality high-strength high-modulus polyformaldehyde fibers.
In order to achieve the purpose, the invention adopts the technical scheme that:
the high-strength high-modulus polyformaldehyde fiber has the tensile strength of more than or equal to 6.5cN/dtex and the tensile modulus of more than or equal to 130 cN/dtex.
The high-strength high-modulus polyformaldehyde fiber has the elongation at break of less than or equal to 9.8%.
The invention also provides a method for preparing the high-strength high-modulus polyformaldehyde fiber, which comprises the steps of extruding a polyformaldehyde melt from a spinneret, cooling the polyformaldehyde melt in air and refrigerating fluid in sequence to obtain filaments, and performing high-power stretching treatment on the filaments to obtain the high-strength high-modulus polyformaldehyde fiber;
the freezing liquid is a water solution of high boiling point alcohols with the temperature less than or equal to 0 ℃, and the high boiling point alcohols refer to alcohols which are not vaporized in the stretching treatment process.
According to the invention, the polyhydric alcohol which has strong interaction with polyformaldehyde molecules is prepared into the aqueous solution to be used as the refrigerating fluid, so that a lower cooling temperature can be provided, crystallization is inhibited by freezing the molecular chain mobility of polyformaldehyde molecules, and the viscosity, the adhesive force and the moisture content of the refrigerating fluid can be used as a spinning oil agent and a lubricant, so that the polyhydric alcohol is used as a small molecular substance to play a lubricating role among polyformaldehyde molecules in the stretching process, and the subsequent high-power drawing of primary fibers can be smoothly carried out.
As a preferred technical scheme:
in the above method, the high-boiling alcohol is ethylene glycol, diethylene glycol, glycerol, isopropanol or sorbitol. The type and concentration of the polyhydric alcohol in the refrigerating fluid are determined according to the required minimum cooling temperature; for example, a 30% by volume aqueous solution of glycerol has a minimum cooling temperature of-9.5 deg.C, while a 56% by volume aqueous solution of ethylene glycol has a minimum cooling temperature of-48 deg.C.
In the method, when the refrigerating fluid is an aqueous solution of glycol, the volume percentage concentration of the refrigerating fluid is preferably 50-60%, and the refrigerating fluid can provide a cooling temperature of-50 to-30 ℃.
The method comprises the following specific steps:
(1) drying polyformaldehyde resin in a vacuum oven, adding the dried polyformaldehyde resin into a screw extruder, heating and melting to obtain polyformaldehyde melt, metering the melt by a metering pump, filtering by a filtering assembly, and extruding through a spinneret;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath containing refrigerating fluid to be cooled to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers; in the process, the refrigerating fluid can cool the polyformaldehyde melt trickle extruded by the spinneret to obtain the nascent fiber, and can play the roles of a spinning oil agent and a lubricant, so that the cohesion of the strand silk and the unwinding of the nascent fiber package in the subsequent drafting process are facilitated, and the movement of a polyformaldehyde molecular chain during the stretching is facilitated;
(3) the high-strength high-modulus polyformaldehyde fiber is obtained by high-power drafting of the nascent fiber through a hot roller, the multiplying power of the high-power drafting is 6-13, the multiplying power is preferably 8 or more, for example, when the multiplying power is 9-11, the broken filament phenomenon in the drafting process is obviously reduced, and the prepared fiber is good in mechanical property.
In the above method, the polyoxymethylene resin is a homopolymer having a molecular structural formula of [ CH ]2-O]nWherein n is an integer greater than 1;
or the polyformaldehyde resin is a copolymer introduced with oxyalkylene repeating units, and the molecular structural formula of the polyformaldehyde resin is shown in the specification
In the formula, m is an integer greater than 1, i is an integer greater than 2, and the molar percentage content of the oxyalkylene repeating unit is 1-10%.
The method has the advantages that the melting point of the polyformaldehyde resin is 160-170 ℃, and the melt index is 2-54 g/10 min.
According to the method, the copolymer is a copolymer of formaldehyde and ethylene oxide, and the molar percentage of the ethylene oxide is 3-5%; the melting point of the polyformaldehyde resin is 160-170 ℃, and the melt index is 15-35 g/10 min.
According to the method, in the step (1), the polyformaldehyde resin needs to be fully dried in a vacuum oven, wherein the drying temperature of the vacuum oven is 80-100 ℃, and the drying time is 2-8 hours; the temperature of a feeding section of the screw extruder is 60-100 ℃, and the temperature of a compression section of the screw extruder is 170-200 ℃; the temperature of the metering pump is 200-220 ℃; the temperature of the filter assembly is 200-230 ℃; the temperature of the spinneret is 200-230 ℃.
In the method, in the step (2), the liquid level of the freezing liquid in the bath tank is 0.5-100 cm away from the spinneret, the temperature of the freezing liquid is-60-0 ℃, and the crystallinity of the nascent fiber is 62-75%. The prior art as-spun fibers typically have a crystallinity of 80% or greater. The distance between the liquid level of the refrigerating liquid and the spinneret is determined according to the ambient temperature of a spinning site, the height is preferably above 150 ℃ when the polyformaldehyde melt enters the refrigerating liquid, and the height is preferably 5-30 cm under the normal room temperature condition.
According to the method, in the step (3), the high-power drafting is performed at one stage or 2-4 stages, the temperature of the high-power drafting is 80-150 ℃, and the speed is 10-100 m/min. The high-power drafting is preferably 2-3 levels of drafting, the multiplying power of each level of drafting is the total drafting multiplying power, and the primary drafting adopts a smaller multiplying power to ensure that the fiber has a certain orientation and can bear the drafting tension and then the multiplying power is increased.
Has the advantages that:
(1) the high-strength high-modulus polyformaldehyde fiber disclosed by the invention has the advantages of few structural defects, high tensile strength and tensile modulus, excellent mechanical property and stable quality;
(2) the preparation method of the high-strength high-modulus polyformaldehyde fiber has the advantages of easily available raw materials, low cost, simplicity and convenience in operation, high efficiency, low failure rate in the spinning process and easiness in realizing industrial production;
(3) the high-strength high-modulus polyformaldehyde fiber disclosed by the invention can be applied to the industrial fields of cement reinforcement, ropes and the like, can also be applied to the military fields of military equipment covering cloth, fishing nets and the like and marine fishery, and is wide in application range.
Detailed Description
The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point is 170 ℃, melt index is 2g/10min, molecular structural formula is [ CH ]2-O]nAfter drying the homopolymerized formaldehyde resin in a vacuum oven at 80 ℃ for 8 hours, adding the homopolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering by a filtering assembly, and extruding the melt through a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 100 ℃, the temperature of a compression section of the screw extruder is 200 ℃, the temperature of the metering pump is 220 ℃, the temperature of the filtering assembly is 220 ℃, and the temperature of the spinning nozzle is 220 ℃;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of ethylene glycol aqueous solution with the volume percentage of 50% and the temperature of-30 ℃ for cooling to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers, wherein the liquid level of the ethylene glycol aqueous solution is 25cm away from the spinning nozzle, and the crystallinity of the nascent fibers is 73%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 7, the temperature is 150 ℃, the speed is 10m/min, and the high-power drafting adopts 1-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 7.3cN/dtex, the tensile modulus of 140.6cN/dtex and the elongation at break of 7.3%.
Comparative example 1
A process for preparing polyoxymethylene fiber, which comprises the steps substantially as in example 1, except that the air and the refrigerant in step (2) are not cooled, the degree of crystallinity of the obtained as-spun fiber is 80%, the drawn polyoxymethylene fiber has a tensile strength of 3.73cN/dtex, a tensile modulus of 65.49cN/dtex, and an elongation at break of 10.04%. Therefore, the high-strength high-modulus polyformaldehyde fiber prepared by the method has high tensile strength and tensile modulus, excellent mechanical property and stable quality.
Example 2
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point is 170 ℃, melt index is 2g/10min, molecular structural formula is [ CH ]2-O]nAfter drying the homopolymerized formaldehyde resin in a vacuum oven at 100 ℃ for 2 hours, adding the homopolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering by a filtering assembly, and extruding the melt through a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 100 ℃, the temperature of a compression section of the screw extruder is 200 ℃, the temperature of the metering pump is 220 ℃, the temperature of the filtering assembly is 220 ℃, and the temperature of the spinning nozzle is 220 ℃;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of ethylene glycol aqueous solution with the volume ratio of 60% and the temperature of-50 ℃ for cooling to obtain filament, and the filament is wound to obtain nascent fiber, wherein the liquid level of the cryogenic liquid is 25cm away from the spinning nozzle, and the crystallinity of the nascent fiber is 66%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 8, the temperature is 110 ℃, the speed is 50m/min, and four-stage drafting is adopted for high-power drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 8.5cN/dtex, the tensile modulus of 143.5cN/dtex and the elongation at break of 9.7 percent.
Example 3
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point is 169 ℃, melt index is 21g/10min, and molecular structural formula is [ CH ]2-O]nAfter being dried in a vacuum oven at 100 ℃ for 3 hours, the homopolymerized formaldehyde resin is added into a screw extruder to be heated and melted to obtain a polyformaldehyde melt, the melt is metered by a metering pump and filtered by a filtering component and then is extruded through a spinning nozzle, and a screw is used in the spinning processThe temperature of the feeding section of the rod extruder is 60 ℃, the temperature of the compression section is 170 ℃, the temperature of the metering pump is 200 ℃, the temperature of the filter assembly is 200 ℃, and the temperature of the spinning nozzle is 200 ℃;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of 30 volume percent of diethylene glycol aqueous solution at the temperature of 0 ℃ for cooling to obtain filament, and the filament is wound to obtain nascent fiber, wherein the liquid level of the diethylene glycol aqueous solution is 0.5cm away from the spinning nozzle, and the crystallinity of the nascent fiber is 75%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 6, the temperature is 150 ℃, the speed is 10m/min, and the high-power drafting adopts 2-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 6.5cN/dtex, the tensile modulus of 130.2cN/dtex and the elongation at break of 7.0%.
Example 4
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point is 167 ℃, melt index is 25g/10min, molecular structural formula is [ CH ]2-O]nAfter drying the homopolymerized formaldehyde resin in a vacuum oven at 100 ℃ for 2 hours, adding the homopolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering by a filtering assembly, and extruding the melt through a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 80 ℃, the temperature of a compression section of the screw extruder is 200 ℃, the temperature of the metering pump is 200 ℃, the temperature of the filtering assembly is 200 ℃, and the temperature of the spinning nozzle is 210 ℃;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of 30 volume percent of glycerol aqueous solution at the temperature of minus 9.5 ℃ for cooling to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers, wherein the liquid level of the glycerol aqueous solution is 65cm away from the spinning nozzle, and the crystallinity of the nascent fibers is 72%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 7, the temperature is 80 ℃, the speed is 10m/min, and the high-power drafting adopts 4-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 8.25cN/dtex, the tensile modulus of 141.9cN/dtex and the elongation at break of 7.6%.
Example 5
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) the melting point is 166 ℃, the melt index is 30g/10min, and the molecular structural formula is shown in
After drying the copolymerized formaldehyde resin (the molar ratio of formaldehyde to ethylene oxide monomers is 99:1) in a vacuum oven at 80 ℃ for 8 hours, adding the copolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering the melt by a filter assembly, and extruding the melt by a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 90 ℃, the temperature of a compression section of the screw extruder is 195 ℃, the temperature of the metering pump is 220 ℃, the temperature of the filter assembly is 230 ℃ and the temperature of the spinning nozzle is 230 ℃ in the spinning process;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of an isopropanol aqueous solution with the volume percentage of 30 and the temperature of 0 ℃ for cooling to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers, wherein the liquid level of the isopropanol aqueous solution is 25cm away from the spinning nozzle, and the crystallinity of the nascent fibers is 71%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 7, the temperature is 110 ℃, the speed is 20m/min, and the high-power drafting adopts 3-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 7.5cN/dtex, the tensile modulus of 144.2cN/dtex and the elongation at break of 7.8%.
Example 6
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point of 163 ℃, melt index of 40g/10min, molecular structural formula of
After drying the copolymerized formaldehyde resin (the molar ratio of formaldehyde to ethylene oxide monomer is 95:5) in a vacuum oven at 85 ℃ for 4 hours, adding the copolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering the melt by a filtering component, and extruding the melt by a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 60 ℃, the temperature of a compression section of the screw extruder is 180 ℃, the temperature of the metering pump is 220 ℃, the temperature of the filtering component is 225 ℃ and the temperature of the spinning nozzle is 225 ℃ in the spinning process;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of sorbitol aqueous solution with the volume percentage of 67% and the temperature of-60 ℃ for cooling to obtain filament yarns, and the filament yarns are wound to obtain nascent fiber, wherein the liquid level of the sorbitol aqueous solution is 0.5cm away from the spinning nozzle, and the crystallinity of the nascent fiber is 62%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 13, the temperature is 120 ℃, the speed is 50m/min, and four-stage drafting is adopted for high-power drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 12.4cN/dtex, the tensile modulus of 209.1cN/dtex and the elongation at break of 9 percent.
Example 7
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) the melting point is 166 ℃, the melt index is 30g/10min, and the molecular structural formula is shown in
After drying the copolymerized formaldehyde resin (the molar ratio of formaldehyde to ethylene oxide monomer is 97:3) in a vacuum oven at 100 ℃ for 6 hours, adding the copolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering the melt by a filter assembly, and extruding the melt by a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 60 ℃, the temperature of a compression section of the screw extruder is 195 ℃, the temperature of the metering pump is 205 ℃, the temperature of the filter assembly is 225 ℃ and the temperature of the spinning nozzle is 230 ℃ in the spinning process;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of ethylene glycol aqueous solution with the volume percentage of 53% and the temperature of minus 40 ℃ for cooling to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers, wherein the liquid level of the ethylene glycol aqueous solution is 50cm away from the spinning nozzle, and the crystallinity of the nascent fibers is 66%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 10, the temperature is 150 ℃, the speed is 80m/min, and the high-power drafting adopts 3-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 10.2cN/dtex, the tensile modulus of 176.1cN/dtex and the elongation at break of 9.8 percent.
Example 8
A preparation method of high-strength high-modulus polyformaldehyde fibers comprises the following specific steps:
(1) melting point of 160 ℃, melt index of 54g/10min, molecular structural formula of
After drying the copolymerized formaldehyde resin (the molar ratio of formaldehyde to ethylene oxide monomers is 90:10) in a vacuum oven at 95 ℃ for 2 hours, adding the copolymerized formaldehyde resin into a screw extruder, heating and melting to obtain a polyformaldehyde melt, metering the melt by a metering pump, filtering the melt by a filtering component, and extruding the melt by a spinning nozzle, wherein the temperature of a feeding section of the screw extruder is 60 ℃, the temperature of a compression section of the screw extruder is 200 ℃, the temperature of the metering pump is 220 ℃, the temperature of the filtering component is 230 ℃ and the temperature of the spinning nozzle is 230 ℃ in the spinning process;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath of 60 volume percent diethylene glycol aqueous solution at the temperature of-50 ℃ for cooling to obtain filament, and the filament is wound to obtain nascent fiber, wherein the liquid level of the diethylene glycol aqueous solution is 100cm away from the spinning nozzle, and the crystallinity of the nascent fiber is 65%;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber, wherein the high-power drafting rate is 11, the temperature is 95 ℃, the speed is 100m/min, and the high-power drafting adopts 2-level drafting.
The high-strength high-modulus polyformaldehyde fiber prepared by the method has the tensile strength of 11.7cN/dtex, the tensile modulus of 211.7cN/dtex and the elongation at break of 7.9%.
Claims (8)
1. A method for preparing high-strength high-modulus polyformaldehyde fibers is characterized by comprising the following steps: the polyformaldehyde melt is extruded from a spinneret and then is sequentially cooled in air and refrigerating fluid to obtain filaments, and the filaments are subjected to high-power drawing treatment to obtain high-strength high-modulus polyformaldehyde fibers;
the refrigerating fluid is an aqueous solution of high-boiling-point alcohols with the temperature of less than or equal to 0 ℃, and the high-boiling-point alcohols are alcohols which are not vaporized in the stretching treatment process;
the high-power drafting multiplying power is 6-13;
the tensile strength of the high-strength high-modulus polyformaldehyde fiber is 7.3-12.4 cN/dtex, and the tensile modulus is more than or equal to 130 cN/dtex; the breaking elongation of the high-strength high-modulus polyformaldehyde fiber is less than or equal to 9.8 percent.
2. The method of claim 1, wherein the high boiling point alcohol is ethylene glycol, diethylene glycol, glycerol, isopropanol, or sorbitol.
3. The method according to claim 1, characterized by the following specific steps:
(1) drying polyformaldehyde resin in a vacuum oven, adding the dried polyformaldehyde resin into a screw extruder, heating and melting to obtain polyformaldehyde melt, metering the melt by a metering pump, filtering by a filtering assembly, and extruding through a spinneret;
(2) after passing through a section of air, the melt trickle extruded by the spinning nozzle enters a bath containing refrigerating fluid to be cooled to obtain filament yarns, and the filament yarns are wound to obtain nascent fibers;
(3) and (3) carrying out high-power drafting on the nascent fiber by using a hot roller to obtain the high-strength high-modulus polyformaldehyde fiber.
4. The method according to claim 3, wherein the polyoxymethylene resin is a homopolymer having a molecular structural formula of [ CH ]2-O]nWherein n is an integer greater than 1;
or the polyformaldehyde resin is a copolymer introduced with oxyalkylene repeating units, and the molecular structural formula of the polyformaldehyde resin is [ CH2-O]n[(CH2)i-O]mWherein m is an integer greater than 1, i is an integer greater than 2, and the molar percentage of the oxyalkylene repeating units is 1-10%.
5. The method according to claim 4, wherein the polyoxymethylene resin has a melting point of 160 to 170 ℃ and a melt index of 2 to 54g/10 min.
6. The method according to claim 3, wherein in the step (1), the temperature for drying in the vacuum oven is 80-100 ℃ and the time is 2-8 h; the temperature of a feeding section of the screw extruder is 60-100 ℃, and the temperature of a compression section of the screw extruder is 170-200 ℃; the temperature of the metering pump is 200-220 ℃; the temperature of the filter assembly is 200-230 ℃; the temperature of the spinneret is 200-230 ℃.
7. The method according to claim 3, wherein in the step (2), the liquid level of the freezing liquid in the bath is 0.5-100 cm away from the spinneret, the temperature of the freezing liquid is-60-0 ℃, and the crystallinity of the nascent fiber is 62-75%.
8. The method according to claim 3, wherein in the step (3), the high power draft is one-stage or 2-4-stage draft, the temperature of the high power draft is 80-150 ℃, and the speed is 10-100 m/min.
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| CN101792938A (en) * | 2010-04-01 | 2010-08-04 | 东华大学 | Novel preparation technology of polyoxymethylene fiber |
| CN102011201A (en) * | 2010-12-15 | 2011-04-13 | 四川省纺织科学研究院 | Melt-spinning method for polyformaldehyde fibers |
| CN103756246A (en) * | 2013-11-13 | 2014-04-30 | 云南云天化股份有限公司 | Spinning-grade polyoxymethylene material and preparation method thereof |
| CN105401254A (en) * | 2015-10-27 | 2016-03-16 | 开滦（集团）有限责任公司 | High-strength and high-modulus polyformaldehyde fiber and two-step hot drawing preparation method thereof |
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| CN101792938A (en) * | 2010-04-01 | 2010-08-04 | 东华大学 | Novel preparation technology of polyoxymethylene fiber |
| CN102011201A (en) * | 2010-12-15 | 2011-04-13 | 四川省纺织科学研究院 | Melt-spinning method for polyformaldehyde fibers |
| CN103756246A (en) * | 2013-11-13 | 2014-04-30 | 云南云天化股份有限公司 | Spinning-grade polyoxymethylene material and preparation method thereof |
| CN105401254A (en) * | 2015-10-27 | 2016-03-16 | 开滦（集团）有限责任公司 | High-strength and high-modulus polyformaldehyde fiber and two-step hot drawing preparation method thereof |
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