CN114457452A - Polyimide fiber and preparation method thereof - Google Patents
Polyimide fiber and preparation method thereof Download PDFInfo
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- CN114457452A CN114457452A CN202210124683.6A CN202210124683A CN114457452A CN 114457452 A CN114457452 A CN 114457452A CN 202210124683 A CN202210124683 A CN 202210124683A CN 114457452 A CN114457452 A CN 114457452A
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- polyamic acid
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- 239000000835 fiber Substances 0.000 title claims abstract description 82
- 239000004642 Polyimide Substances 0.000 title claims abstract description 55
- 229920001721 polyimide Polymers 0.000 title claims abstract description 55
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 229920005575 poly(amic acid) Polymers 0.000 claims abstract description 92
- 238000000034 method Methods 0.000 claims abstract description 58
- 230000001112 coagulating effect Effects 0.000 claims abstract description 28
- 238000001035 drying Methods 0.000 claims abstract description 23
- 238000007363 ring formation reaction Methods 0.000 claims abstract description 21
- 238000001891 gel spinning Methods 0.000 claims abstract description 19
- 238000009987 spinning Methods 0.000 claims description 92
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 60
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 40
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 39
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 28
- 239000007787 solid Substances 0.000 claims description 22
- 238000003756 stirring Methods 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 21
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 229910052757 nitrogen Inorganic materials 0.000 claims description 20
- 238000012643 polycondensation polymerization Methods 0.000 claims description 20
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 claims description 14
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 claims description 14
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 14
- 239000000178 monomer Substances 0.000 claims description 13
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 7
- 239000003054 catalyst Substances 0.000 claims description 7
- 239000012024 dehydrating agents Substances 0.000 claims description 7
- QQGYZOYWNCKGEK-UHFFFAOYSA-N 5-[(1,3-dioxo-2-benzofuran-5-yl)oxy]-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(OC=2C=C3C(=O)OC(C3=CC=2)=O)=C1 QQGYZOYWNCKGEK-UHFFFAOYSA-N 0.000 claims description 6
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 6
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 6
- 150000004985 diamines Chemical class 0.000 claims description 6
- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 claims description 6
- BSKHPKMHTQYZBB-UHFFFAOYSA-N 2-methylpyridine Chemical compound CC1=CC=CC=N1 BSKHPKMHTQYZBB-UHFFFAOYSA-N 0.000 claims description 4
- ITQTTZVARXURQS-UHFFFAOYSA-N 3-methylpyridine Chemical compound CC1=CC=CN=C1 ITQTTZVARXURQS-UHFFFAOYSA-N 0.000 claims description 4
- 239000007810 chemical reaction solvent Substances 0.000 claims description 4
- AWJUIBRHMBBTKR-UHFFFAOYSA-N isoquinoline Chemical compound C1=NC=CC2=CC=CC=C21 AWJUIBRHMBBTKR-UHFFFAOYSA-N 0.000 claims description 4
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 claims description 4
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 2
- XAFOTXWPFVZQAZ-UHFFFAOYSA-N 2-(4-aminophenyl)-3h-benzimidazol-5-amine Chemical compound C1=CC(N)=CC=C1C1=NC2=CC=C(N)C=C2N1 XAFOTXWPFVZQAZ-UHFFFAOYSA-N 0.000 claims description 2
- -1 3 ' Chemical compound 0.000 claims description 2
- NBAUUNCGSMAPFM-UHFFFAOYSA-N 3-(3,4-dicarboxyphenyl)phthalic acid Chemical compound C1=C(C(O)=O)C(C(=O)O)=CC=C1C1=CC=CC(C(O)=O)=C1C(O)=O NBAUUNCGSMAPFM-UHFFFAOYSA-N 0.000 claims description 2
- NVKGJHAQGWCWDI-UHFFFAOYSA-N 4-[4-amino-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)aniline Chemical group FC(F)(F)C1=CC(N)=CC=C1C1=CC=C(N)C=C1C(F)(F)F NVKGJHAQGWCWDI-UHFFFAOYSA-N 0.000 claims description 2
- CQMIJLIXKMKFQW-UHFFFAOYSA-N 4-phenylbenzene-1,2,3,5-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C(C(=O)O)=CC(C(O)=O)=C1C1=CC=CC=C1 CQMIJLIXKMKFQW-UHFFFAOYSA-N 0.000 claims description 2
- VQVIHDPBMFABCQ-UHFFFAOYSA-N 5-(1,3-dioxo-2-benzofuran-5-carbonyl)-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(C(C=2C=C3C(=O)OC(=O)C3=CC=2)=O)=C1 VQVIHDPBMFABCQ-UHFFFAOYSA-N 0.000 claims description 2
- ZHBXLZQQVCDGPA-UHFFFAOYSA-N 5-[(1,3-dioxo-2-benzofuran-5-yl)sulfonyl]-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(S(=O)(=O)C=2C=C3C(=O)OC(C3=CC=2)=O)=C1 ZHBXLZQQVCDGPA-UHFFFAOYSA-N 0.000 claims description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 2
- YHASWHZGWUONAO-UHFFFAOYSA-N butanoyl butanoate Chemical compound CCCC(=O)OC(=O)CCC YHASWHZGWUONAO-UHFFFAOYSA-N 0.000 claims description 2
- LTYMSROWYAPPGB-UHFFFAOYSA-N diphenyl sulfide Chemical compound C=1C=CC=CC=1SC1=CC=CC=C1 LTYMSROWYAPPGB-UHFFFAOYSA-N 0.000 claims description 2
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 2
- WYVAMUWZEOHJOQ-UHFFFAOYSA-N propionic anhydride Chemical compound CCC(=O)OC(=O)CC WYVAMUWZEOHJOQ-UHFFFAOYSA-N 0.000 claims description 2
- 125000006158 tetracarboxylic acid group Chemical group 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 239000002253 acid Substances 0.000 abstract description 3
- 239000004952 Polyamide Substances 0.000 abstract description 2
- 229920002647 polyamide Polymers 0.000 abstract description 2
- 238000005406 washing Methods 0.000 abstract 1
- 208000012886 Vertigo Diseases 0.000 description 85
- 239000000243 solution Substances 0.000 description 75
- 239000002904 solvent Substances 0.000 description 19
- 239000007864 aqueous solution Substances 0.000 description 18
- WKDNYTOXBCRNPV-UHFFFAOYSA-N bpda Chemical compound C1=C2C(=O)OC(=O)C2=CC(C=2C=C3C(=O)OC(C3=CC=2)=O)=C1 WKDNYTOXBCRNPV-UHFFFAOYSA-N 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 12
- 238000002166 wet spinning Methods 0.000 description 11
- 238000001879 gelation Methods 0.000 description 10
- 230000007547 defect Effects 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 238000000578 dry spinning Methods 0.000 description 2
- 238000007380 fibre production Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- ODJQKYXPKWQWNK-UHFFFAOYSA-N 3,3'-Thiobispropanoic acid Chemical compound OC(=O)CCSCCC(O)=O ODJQKYXPKWQWNK-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 150000003949 imides Chemical class 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
Images
Classifications
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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
- D01F6/74—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1003—Preparatory processes
- C08G73/1007—Preparatory processes from tetracarboxylic acids or derivatives and diamines
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
- C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
- C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
- C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
- C08G73/1071—Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain
-
- 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
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
- D01D10/02—Heat treatment
-
- 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
- D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
- D01D10/06—Washing or drying
-
- 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
-
- 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
- D01F6/78—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolycondensation products
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Textile Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)
Abstract
The invention relates to a polyimide fiber and a preparation method thereof, wherein the method comprises the following steps: according to the dry-wet spinning process, the slightly gelled polyamic acid with a certain pre-imidization degree is extruded by a spinneret and then enters a coagulating bath through an air layer; then obtaining partially imidized fiber after washing and drying; finally, the polyimide fiber is obtained through further thermal cyclization. The spraying-drawing ratio of the slightly gelled polyamide acid fiber at the air layer stage can reach more than 10, the production efficiency and the orientation degree of the polyimide fiber are greatly improved, and the prepared polyimide fiber has more excellent mechanical properties.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to a polyimide fiber and a preparation method thereof.
Technical Field
The polyimide fiber has good thermal mechanical properties, excellent ultraviolet radiation resistance, acid and alkali corrosion resistance, flame retardant property and the like, and is widely applied to the high temperature resistant fields of aerospace, atomic energy industry, high temperature dust removal bags, firefighter uniforms and the like.
The common preparation method of the polyimide fiber mainly comprises a one-step method and a two-step method of solution spinning. The one-step method adopts the polyimide solution for spinning, the protofilament does not need subsequent thermal imidization, the fiber structure defect caused by water molecule removal in the two-step method spinning process is avoided, and the polyimide fiber with excellent mechanical property can be conveniently prepared. However, a phenolic solvent with high toxicity is generally adopted, and the monomer types have certain limitation, so that a two-step method is mostly adopted for preparing the polyimide fiber at present.
The two-step wet spinning method is the most common two-step spinning method at present, has simple process flow and low requirements on solution properties, but fibers easily form a sheath-core structure at the coagulation bath stage, so that the jet-draw ratio at the initial stage is limited, and the spinning speed is low and the production efficiency is low. In order to solve the problems, dry spinning and dry-wet spinning processes are developed on the basis of wet spinning. The patent CN 102242415B adopts a dry spinning preparation method to improve the spinnability and post-processing characteristics of the polyimide fiber, but the mechanical properties of the prepared polyimide fiber are not reported. Patent CN 101338452B discloses a method for preparing polyimide fiber by a dry-wet method, wherein the defects of inaccurate temperature control and complex operation of a two-section heating furnace technology are overcome by a gradient temperature rise mode adopted in the imide process, but the heat treatment temperature range is 50-500 ℃, the temperature rise rate is 1-10 ℃/min, the thermal imidization time needs 1-10 hours, and the production efficiency is not high.
Although the research and improvement of the polyimide fiber preparation method exist in the prior art, at present, a series of problems still exist, such as that the fiber is easy to form a sheath-core structure in the coagulation bath stage of the current fiber preparation technology, the jet-draw ratio in the initial stage of spinning is limited, and the spinning speed is slow and the production efficiency is not high on the whole. Therefore, it is desired to develop a method for producing a polyimide fiber, which can effectively increase the initial jet draw ratio of the fiber and improve the production efficiency and the degree of fiber orientation.
Disclosure of Invention
The invention aims to overcome the defects that fibers are easy to crust and form a defective structure in a coagulating bath stage of the traditional two-step wet spinning process, so that the mechanical property of the fibers is influenced, and the traditional dry-wet spinning process has long imidization time and low production efficiency. The method can greatly improve the spray-draw ratio of the initial stage of the fiber, improve the production efficiency and the degree of fiber orientation, and the prepared polyimide fiber has more excellent mechanical properties.
According to the method, the imidization reagent is added into the polyamic acid solution to obtain the polyamic acid with a certain pre-imidization degree and micro-gelation, so that the polyamic acid nascent fiber with a specific micro-gelation form is prepared, has high initial strength, can bear a high spray-draw ratio in an air layer stage between a subsequent spinneret plate and a coagulating bath, and can improve the fiber production efficiency in the initial stage.
Meanwhile, in the process flow of the preparation method of the polyimide fiber, an air layer is designed and reserved between the spinning nozzle and the coagulating bath, so that the complicated modification of the traditional two-step wet spinning equipment is omitted. Meanwhile, due to the existence of the air layer, the effective initial stretching time and the effective aging time are improved, the defects of the surface and the internal structure of the PI fiber can be further reduced, and the further improvement of the mechanical property of the fiber is facilitated.
In order to achieve the above object, the polyimide fiber and the preparation method thereof claimed by the present invention comprises the following steps:
(1) adding a diamine monomer and a dianhydride monomer into a reaction solvent, fully stirring, carrying out a condensation polymerization reaction to obtain a homogeneous polyamic acid solution, and controlling the solid content ratio of the polyamic acid solution to be 10-30%;
(2) adding a certain amount of dehydrating agent and catalyst into the polyamic acid solution according to a certain proportion, and fully stirring to obtain the slightly gelled polyamic acid with a certain pre-imidization degree, wherein the pre-imidization degree is 20-40%;
(3) spinning the obtained slightly gelled polyamic acid according to a dry-wet spinning process, extruding the spinning solution through a spinning nozzle, and allowing the spinning solution to enter a coagulating bath through an air layer, wherein the stage is used for performing high-power drafting on nascent fibers; the spinning tank is filled with nitrogen, the pressure is 0.2-0.5MPa, and the solution is pushed to a spinneret plate or pushed to the spinneret plate by a metering pump;
(4) ) passing the protofilament through a tube furnace at a temperature of 60-120 deg.C at constant speed for drying for 1-6 min. Then, the dried fiber is passed through a tubular furnace with the temperature of 350-500 ℃ at constant speed for further thermal cyclization treatment for 1-6min, and the polyimide fiber which is fully imidized is obtained.
Preferably, the solid content of the polyamic acid solution in step (1) is 10% to 20%. The molar ratio of dianhydride monomer to diamine monomer is 0.98:1-1.02: 1.
Preferably, the dianhydride monomer in step (1) is one or more of 3,3 ', 4,4 ' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 3 ', 4,4 ' -biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 2,3 ', 3,4 ' -biphenyl tetracarboxylic dianhydride (α -BPDA), bisphenol a type dianhydride (BPADA), 4,4 ' -oxydiphthalic anhydride (ODPA), hexafluoroisopropylene phthalic acid (6FDA), diphenyl sulfide Tetracarboxylic Dianhydride (TDPA), and 3,3 ', 4,4 ' -diphenyl sulfone tetracarboxylic dianhydride mixed in any proportion; the diamine monomer is one or more of p-Phenylenediamine (PDA), m-phenylenediamine, 4 '-diaminodiphenyl ether (ODA), 2- (4-aminophenyl) -5-aminobenzimidazole (BIA), 4' -diaminodiphenyl sulfone and 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl mixed in any proportion; the reaction solvent is one of N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-vinyl pyrrolidone (NMP) and dimethyl sulfoxide (DMSO).
Preferably, the volume ratio of the dehydrating agent to the catalyst in the step (2) is 2:1 to 1: 5.
Preferably, the dehydrating agent in the step (2) is one or more of acetic anhydride, propionic anhydride and butyric anhydride; the catalyst is one or a mixture of pyridine, triethylamine, imidazole, isoquinoline, 2-methylpyridine and 3-methylpyridine.
Another object of the present invention is to provide a polyimide fiber having excellent mechanical properties, which is prepared by the above method.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method of the invention obtains the polyamic acid with a certain pre-imidization degree and micro-gelation by adding a certain amount of dehydrating agent and catalyst into the polyamic acid solution, the micro-gelation polyamic acid nascent fiber prepared by the method has higher strength, can bear larger spray-draw ratio at the stage of an air layer between a spinneret plate and a coagulating bath, and further improves the production efficiency of the fiber;
(2) the polyimide fiber prepared by the method has higher orientation degree and mechanical property;
(3) the preparation method of the polyimide fiber only needs to reserve an air layer between the spinning nozzle and the coagulating bath, does not need to modify the traditional two-step wet spinning equipment, is simple to operate and is convenient for industrial production. And the existence of the air layer reduces the defects of the PI fiber surface and the internal structure, and is beneficial to further improving the mechanical property of the fiber.
Drawings
FIG. 1 is a schematic diagram of a dry-wet spinning process for polyimide fibers;
FIG. 2 is the rheological behavior of the solution during the chemical imidization process of example 1 (polyamic acid microgel dots at the interface of zone I and zone II);
FIG. 3 is an IR spectrum at the microgel spot of polyamic acid of example 1.
In the embodiment, the microgel point of the polyamic acid solution can be determined by a rheological curve, and the imidization degree at the microgel point can be determined by an infrared spectrogram, so that the addition amount of the imidization agent can be calculated.
Detailed Description
The present invention will be further described with reference to specific examples, but the present invention is not limited to the following examples. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar modules or modules having the same or similar functionality throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description herein, references to the description of "one embodiment," "another embodiment," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
The preparation process flow of the polyimide fiber provided by the invention is shown in figure 1, and comprises the following general flows: preparing raw materials → polymerizing reaction → obtaining polyamic acid solution → adding chemical imidization reagent → obtaining micro-gelated polyamic acid spinning solution → spinning → extruding through air layer → drafting thread line with high power → entering coagulating bath → entering water bath → drying → collecting thread to obtain finished fiber.
The spinning solution is subjected to relevant equipment in sequence in the whole fiber preparation process, wherein the relevant equipment comprises: spinneret → air layer → spinning roller → coagulating bath → water bath → drying oven → take-up roller.
In the preparation process of the polyimide fiber, the state and the tissue form of the gelled polyamide acid spinning solution obtained in the intermediate step have important influence on the subsequent spinning process, and the preparation process has higher strength and can bear larger spray-draw ratio, and has important effect on improving the production efficiency of the fiber.
Specific example embodiments of the invention are set forth clearly below.
Example 1
(1) Adding PMDA and ODA with equimolar amounts into a DMAc solvent, stirring, and carrying out condensation polymerization to obtain a polyamic acid solution with a solid content of 15%;
(2) acetic anhydride and pyridine were added to the foregoing polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid having a degree of pre-imidization of 40%. Wherein the molar ratio of acetic anhydride to PMDA is 0.8:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.35MPa, and then entering a coagulating bath (aqueous solution with 7% volume fraction of DMAc) through an air layer of 30mm, wherein the spray-draw ratio is 15, and the spinning speed is 120 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 460 ℃, the drafting ratio is 4.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
In the scheme (2) of preparing the fiber of example 1, the rheological behavior of the solution during the chemical imidization process is shown in fig. 2, wherein the junction between the region i and the region ii is a polyamic acid microgel point, and the infrared spectrum of the polyamic acid microgel point shown in fig. 3 is combined, so that the amount of the imidization reagent required can be accurately determined in the experiment, and the aim of accurately controlling the imidization degree is achieved.
Comparative example 1
(1) Adding PMDA and ODA with equimolar amount into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.35MPa, enters a coagulating bath (aqueous solution with 7% DMAc volume fraction) through a 30mm air layer, the spray-draw ratio is 8, and the spinning speed is 80 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 460 ℃, the drafting ratio is 4.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 2
(1) Adding PMDA and ODA with equimolar amount into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.35MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 3, and the spinning speed is 20 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 460 ℃, the drafting ratio is 4.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
TABLE 1 comparison of mechanical Properties of polyimide fibers obtained by different methods
Example 2
(1) Adding equal molar weight of BPDA and PDA into DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 12%;
(2) acetic anhydride and pyridine were added to the foregoing polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid having a degree of pre-imidization of 30%. Wherein the molar ratio of acetic anhydride to BPDA is 0.6:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.35MPa, and then entering a coagulating bath (aqueous solution with 7% of DMAc volume fraction) through a 35mm air layer, wherein the spray-draw ratio is 13, and the spinning speed is 105 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 470 ℃, the drafting ratio is 2.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 3
(1) Adding equal molar weight of BPDA and PDA into DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 12%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.35MPa, enters a coagulating bath (aqueous solution with 7% DMAc volume fraction) through a 35mm air layer, the spray-draw ratio is 7, and the spinning speed is 70 m/min;
(3) drying the polyamic acid protofilament in a tubular furnace at a constant speed and at a temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 470 ℃, the drafting ratio is 2.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 4
(1) Adding equal molar weight of BPDA and PDA into DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 12%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.35MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 3, and the spinning speed is 20 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tubular furnace at the temperature of 470 ℃, the drafting ratio is 2.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
TABLE 2 comparison of mechanical Properties of polyimide fibers obtained by different methods
Example 3
(1) Adding BPDA/PMDA/PDA with the molar ratio of 5/5/10 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) acetic anhydride and pyridine were added to the foregoing polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid having a degree of pre-imidization of 20%. Wherein the molar ratio of acetic anhydride to PDA is 0.4:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.35MPa, and then entering a coagulating bath (aqueous solution with 7% volume fraction of DMAc) through a 50mm air layer, wherein the spray-draw ratio is 14, and the spinning speed is 130 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 1.5, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 5
(1) Adding BPDA/PMDA/PDA with the molar ratio of 5/5/10 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.35MPa, enters a coagulating bath (a 7% DMAc aqueous solution by volume fraction) through a 50mm air layer, the spray-draw ratio is 7, and the spinning speed is 75 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 1.5, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 6
(1) Adding BPDA/PMDA/PDA with the molar ratio of 5/5/10 into a DMAc solvent, stirring, and performing condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.35MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 3, and the spinning speed is 25 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 1.5, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
TABLE 3 comparison of mechanical Properties of polyimide fibers obtained by different methods
Example 4
(1) Adding BPDA/PDA/ODA with the molar ratio of 10/6/4 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) acetic anhydride and pyridine were added to the foregoing polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid having a degree of pre-imidization of 40%. Wherein the molar ratio of acetic anhydride to BPDA is 0.8:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.35MPa, and then entering a coagulating bath (aqueous solution with 7% of DMAc volume fraction) through a 45mm air layer, wherein the spray-draw ratio is 13, and the spinning speed is 125 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tube furnace with the temperature of 450 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 5.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
Comparative example 7
(1) Adding BPDA/PDA/ODA with the molar ratio of 10/6/4 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.35MPa, enters a coagulating bath (aqueous solution with 7% DMAc volume fraction) through a 45mm air layer, the spray-draw ratio is 7, and the spinning speed is 75 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tube furnace with the temperature of 450 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 5.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
Comparative example 8
(1) Adding BPDA/PDA/ODA with the molar ratio of 10/6/4 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.35MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 2, and the spinning speed is 22 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tube furnace with the temperature of 450 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 5.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
TABLE 4 comparison of mechanical Properties of polyimide fibers obtained by different methods
Example 5
(1) Adding PMDA/PDA/BIA with the molar ratio of 10/5/5 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) acetic anhydride and pyridine were added to the polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid spinning solution having a degree of pre-imidization of 30%. Wherein the molar ratio of acetic anhydride to PMDA is 0.6:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.40MPa, and then entering a coagulating bath (aqueous solution with 7% volume fraction of DMAc) through a 40mm air layer, wherein the spray-draw ratio is 16, and the spinning speed is 155 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tubular furnace at the temperature of 490 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 1.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
Comparative example 9
(1) Adding PMDA/PDA/BIA with the molar ratio of 10/5/5 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.40MPa, enters a coagulating bath (aqueous solution with 7% DMAc volume fraction) through a 40mm air layer, the spray-draw ratio is 8, and the spinning speed is 80 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tubular furnace at the temperature of 490 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 1.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
Comparative example 10
(1) Adding PMDA/PDA/BIA with the molar ratio of 10/5/5 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.40MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 4, and the spinning speed is 30 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; and then, passing through a tubular furnace at the temperature of 490 ℃ at a constant speed for thermal cyclization and drafting, wherein the drafting ratio is 1.5, and the time is 2min, thus obtaining the polyimide fiber which is fully imidized.
TABLE 5 comparison of mechanical Properties of polyimide fibers obtained by different methods
Example 6
(1) Adding BPDA/ODPA/PDA with the molar ratio of 7/3/10 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) acetic anhydride and pyridine were added to the foregoing polyamic acid solution, and the mixture was sufficiently stirred to obtain a microgel polyamic acid having a degree of pre-imidization of 35%. Wherein the molar ratio of acetic anhydride to PDA is 0.7:1, and the volume ratio of acetic anhydride to pyridine is 2: 1;
(3) spinning the obtained polyamic acid with a certain pre-imidization degree and micro-gelation according to a dry-wet spinning process, extruding the spinning solution from a spinning nozzle under the nitrogen pressure of 0.40MPa, and then entering a coagulating bath (aqueous solution with 7% volume fraction of DMAc) through a 50mm air layer, wherein the spray-draw ratio is 12, and the spinning speed is 115 m/min;
(4) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 3.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 11
(1) Adding BPDA/ODPA/PDA with the molar ratio of 7/3/10 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a dry-wet spinning process, wherein the spinning solution is extruded from a spinning nozzle under the nitrogen pressure of 0.40MPa, enters a coagulating bath (aqueous solution with 7% DMAc volume fraction) through a 50mm air layer, the spray-draw ratio is 5, and the spinning speed is 45 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 3.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
Comparative example 12
(1) Adding BPDA/ODPA/PDA with the molar ratio of 7/3/10 into a DMAc solvent, stirring, and carrying out condensation polymerization reaction to obtain a polyamic acid solution with the solid content of 15%;
(2) spinning the polyamic acid solution according to a wet spinning process, wherein the spinning solution is extruded from a spinneret under the nitrogen pressure of 0.40MPa and then enters a coagulating bath (an aqueous solution with 7% DMAc volume fraction), the spray-draw ratio is 2.5, and the spinning speed is 20 m/min;
(3) drying the polyamic acid protofilament at a constant speed in a tube furnace at the temperature of 130 ℃ for 3 min; then, the mixture is subjected to thermal cyclization and drafting at a constant speed in a tube furnace at the temperature of 450 ℃, the drafting ratio is 3.0, and the time is 2min, so that the polyimide fiber which is fully imidized is obtained.
TABLE 6 comparison of mechanical Properties of polyimide fibers obtained by different methods
As can be seen from tables 1-6, the dry-wet spinning process provided by the invention can greatly improve the spray-draw ratio of the fiber at the air layer stage, improve the fiber production efficiency and the orientation degree, and the prepared polyimide fiber has more excellent mechanical properties.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of the technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (6)
1. A polyimide fiber and a preparation method thereof comprise the following steps:
(1) adding a diamine monomer and a dianhydride monomer into a reaction solvent, fully stirring, carrying out a condensation polymerization reaction to obtain a homogeneous polyamic acid solution, and controlling the solid content ratio of the polyamic acid solution to be 10-30%;
(2) adding a certain amount of dehydrating agent and catalyst into the polyamic acid solution according to a certain proportion, and fully stirring to obtain the slightly gelled polyamic acid with a certain pre-imidization degree, wherein the pre-imidization degree is 20-40%;
(3) spinning the obtained slightly gelled polyamic acid according to a dry-wet spinning process, extruding the spinning solution through a spinning nozzle, and allowing the spinning solution to enter a coagulating bath through an air layer, wherein the stage is used for performing high-power drafting on nascent fibers; the spinning tank is filled with nitrogen, the pressure is 0.2-0.5MPa, and the solution is pushed to a spinneret plate or pushed to the spinneret plate by a metering pump;
(4) ) drying the protofilament at a constant speed for 1-6min by passing through a tubular furnace at the temperature of 60-120 ℃; then, the dried fiber is passed through a tubular furnace with the temperature of 350-500 ℃ at constant speed for further thermal cyclization treatment for 1-6min, and the polyimide fiber which is fully imidized is obtained.
2. The method according to claim 1, wherein the solid content of the polyamic acid solution in step (1) is 10% to 30%; the molar ratio of dianhydride monomer to diamine monomer is 0.98:1-1.02: 1.
3. The method according to claim 1 or 2, wherein the dianhydride monomer in step (1) is one or more of 3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride, 3 ', 4,4 ' -biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, 2,3 ', 3,4 ' -biphenyl tetracarboxylic dianhydride, bisphenol a type dianhydride, 4,4 ' -oxydiphthalic anhydride, hexafluoroisopropylene phthalic acid, diphenyl sulfide tetracarboxylic dianhydride, and 3,3 ', 4,4 ' -diphenyl sulfone tetracarboxylic dianhydride mixed in an arbitrary ratio; the diamine monomer is one or more of p-phenylenediamine, m-phenylenediamine, 4 '-diaminodiphenyl ether, 2- (4-aminophenyl) -5-aminobenzimidazole, 4' -diaminodiphenyl sulfone and 4,4 '-diamino-2, 2' -bistrifluoromethyl biphenyl which are mixed in any proportion; the reaction solvent is one of N, N-dimethylformamide, N-dimethylacetamide, N-vinyl pyrrolidone and dimethyl sulfoxide.
4. The process according to claim 1, wherein the volume ratio of the dehydrating agent to the catalyst in step (2) is from 2:1 to 1: 5.
5. The method according to claim 1, wherein the dehydrating agent in step (2) is a mixture of one or more of acetic anhydride, propionic anhydride, butyric anhydride; the catalyst is one or a mixture of pyridine, triethylamine, imidazole, isoquinoline, 2-methylpyridine and 3-methylpyridine.
6. A polyimide fiber prepared according to the method of any one of claims 1 to 5.
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| CN115652474A (en) * | 2022-09-28 | 2023-01-31 | 清华大学 | Method for preparing fiber of imide copolymer from amic acid copolymer and fiber prepared thereby |
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