CN117248288A - Preparation method of polyamide 6 fiber - Google Patents
Preparation method of polyamide 6 fiber Download PDFInfo
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- CN117248288A CN117248288A CN202210657022.XA CN202210657022A CN117248288A CN 117248288 A CN117248288 A CN 117248288A CN 202210657022 A CN202210657022 A CN 202210657022A CN 117248288 A CN117248288 A CN 117248288A
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- polyamide
- melt
- falling film
- reactor
- caprolactam
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- 229920002292 Nylon 6 Polymers 0.000 title claims abstract description 131
- 239000000835 fiber Substances 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title abstract description 10
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 claims abstract description 139
- 239000011552 falling film Substances 0.000 claims abstract description 131
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 86
- 238000006243 chemical reaction Methods 0.000 claims abstract description 49
- 238000009987 spinning Methods 0.000 claims abstract description 48
- 239000012632 extractable Substances 0.000 claims abstract description 37
- 238000004519 manufacturing process Methods 0.000 claims abstract description 24
- 239000010408 film Substances 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims description 43
- 238000007792 addition Methods 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 35
- 238000007142 ring opening reaction Methods 0.000 claims description 26
- 230000007062 hydrolysis Effects 0.000 claims description 24
- 238000006460 hydrolysis reaction Methods 0.000 claims description 24
- 230000035484 reaction time Effects 0.000 claims description 24
- 238000009833 condensation Methods 0.000 claims description 22
- 230000005494 condensation Effects 0.000 claims description 22
- 238000006068 polycondensation reaction Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 17
- 238000000605 extraction Methods 0.000 claims description 16
- 229920000642 polymer Polymers 0.000 claims description 10
- 238000007599 discharging Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000002253 acid Substances 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 238000007259 addition reaction Methods 0.000 claims description 5
- 239000003963 antioxidant agent Substances 0.000 claims description 5
- 230000003078 antioxidant effect Effects 0.000 claims description 5
- -1 delustrant Substances 0.000 claims description 5
- 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 claims description 4
- 239000003054 catalyst Substances 0.000 claims description 4
- 239000003086 colorant Substances 0.000 claims description 4
- 150000004985 diamines Chemical class 0.000 claims description 4
- 239000003063 flame retardant Substances 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000009792 diffusion process Methods 0.000 claims description 3
- 238000006116 polymerization reaction Methods 0.000 abstract description 47
- 239000000203 mixture Substances 0.000 abstract description 19
- 230000008901 benefit Effects 0.000 abstract description 6
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 238000003809 water extraction Methods 0.000 abstract description 5
- 238000001035 drying Methods 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 230000005484 gravity Effects 0.000 abstract description 3
- 230000000379 polymerizing effect Effects 0.000 abstract 1
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 56
- 239000000155 melt Substances 0.000 description 37
- 230000008569 process Effects 0.000 description 25
- 239000000126 substance Substances 0.000 description 17
- 238000003756 stirring Methods 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 238000001914 filtration Methods 0.000 description 14
- 238000012546 transfer Methods 0.000 description 10
- 239000000289 melt material Substances 0.000 description 8
- 230000001276 controlling effect Effects 0.000 description 7
- 230000003301 hydrolyzing effect Effects 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 238000010036 direct spinning Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 5
- 239000000049 pigment Substances 0.000 description 5
- 230000001105 regulatory effect Effects 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 125000001931 aliphatic group Chemical group 0.000 description 4
- 125000003118 aryl group Chemical group 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000002349 favourable effect Effects 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000002074 melt spinning Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- SLXKOJJOQWFEFD-UHFFFAOYSA-N 6-aminohexanoic acid Chemical compound NCCCCCC(O)=O SLXKOJJOQWFEFD-UHFFFAOYSA-N 0.000 description 2
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 229960002684 aminocaproic acid Drugs 0.000 description 2
- 150000004984 aromatic diamines Chemical class 0.000 description 2
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229920002994 synthetic fiber Polymers 0.000 description 2
- 239000012209 synthetic fiber Substances 0.000 description 2
- 239000004753 textile Substances 0.000 description 2
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 description 2
- XBTRYWRVOBZSGM-UHFFFAOYSA-N (4-methylphenyl)methanediamine Chemical compound CC1=CC=C(C(N)N)C=C1 XBTRYWRVOBZSGM-UHFFFAOYSA-N 0.000 description 1
- GEYOCULIXLDCMW-UHFFFAOYSA-N 1,2-phenylenediamine Chemical compound NC1=CC=CC=C1N GEYOCULIXLDCMW-UHFFFAOYSA-N 0.000 description 1
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 1
- NZTGGRGGJFCKGG-UHFFFAOYSA-N 1,4-diamino-2,3-diphenoxyanthracene-9,10-dione Chemical compound C=1C=CC=CC=1OC1=C(N)C=2C(=O)C3=CC=CC=C3C(=O)C=2C(N)=C1OC1=CC=CC=C1 NZTGGRGGJFCKGG-UHFFFAOYSA-N 0.000 description 1
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 description 1
- LNETULKMXZVUST-UHFFFAOYSA-N 1-naphthoic acid Chemical compound C1=CC=C2C(C(=O)O)=CC=CC2=C1 LNETULKMXZVUST-UHFFFAOYSA-N 0.000 description 1
- VEORPZCZECFIRK-UHFFFAOYSA-N 3,3',5,5'-tetrabromobisphenol A Chemical compound C=1C(Br)=C(O)C(Br)=CC=1C(C)(C)C1=CC(Br)=C(O)C(Br)=C1 VEORPZCZECFIRK-UHFFFAOYSA-N 0.000 description 1
- CGLVZFOCZLHKOH-UHFFFAOYSA-N 8,18-dichloro-5,15-diethyl-5,15-dihydrodiindolo(3,2-b:3',2'-m)triphenodioxazine Chemical compound CCN1C2=CC=CC=C2C2=C1C=C1OC3=C(Cl)C4=NC(C=C5C6=CC=CC=C6N(C5=C5)CC)=C5OC4=C(Cl)C3=NC1=C2 CGLVZFOCZLHKOH-UHFFFAOYSA-N 0.000 description 1
- 239000004114 Ammonium polyphosphate Substances 0.000 description 1
- 239000005711 Benzoic acid Substances 0.000 description 1
- VRAHPESAMYMDQI-UHFFFAOYSA-N Nicomol Chemical compound C1CCC(COC(=O)C=2C=NC=CC=2)(COC(=O)C=2C=NC=CC=2)C(O)C1(COC(=O)C=1C=NC=CC=1)COC(=O)C1=CC=CN=C1 VRAHPESAMYMDQI-UHFFFAOYSA-N 0.000 description 1
- 229920002302 Nylon 6,6 Chemical class 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- JKIJEFPNVSHHEI-UHFFFAOYSA-N Phenol, 2,4-bis(1,1-dimethylethyl)-, phosphite (3:1) Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP(OC=1C(=CC(=CC=1)C(C)(C)C)C(C)(C)C)OC1=CC=C(C(C)(C)C)C=C1C(C)(C)C JKIJEFPNVSHHEI-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- BGYHLZZASRKEJE-UHFFFAOYSA-N [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxy]-2,2-bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxymethyl]propyl] 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CCC(=O)OCC(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)=C1 BGYHLZZASRKEJE-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 150000001413 amino acids Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 235000019826 ammonium polyphosphate Nutrition 0.000 description 1
- 229920001276 ammonium polyphosphate Polymers 0.000 description 1
- 238000010539 anionic addition polymerization reaction Methods 0.000 description 1
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 description 1
- QFFVPLLCYGOFPU-UHFFFAOYSA-N barium chromate Chemical compound [Ba+2].[O-][Cr]([O-])(=O)=O QFFVPLLCYGOFPU-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000010233 benzoic acid Nutrition 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- XCJYREBRNVKWGJ-UHFFFAOYSA-N copper(II) phthalocyanine Chemical compound [Cu+2].C12=CC=CC=C2C(N=C2[N-]C(C3=CC=CC=C32)=N2)=NC1=NC([C]1C=CC=CC1=1)=NC=1N=C1[C]3C=CC=CC3=C2[N-]1 XCJYREBRNVKWGJ-UHFFFAOYSA-N 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- LYMBWJDBLCMHBO-UHFFFAOYSA-N cyclooctane;1,2,3,4,5,5-hexachlorocyclopenta-1,3-diene Chemical compound C1CCCCCCC1.ClC1=C(Cl)C(Cl)(Cl)C(Cl)=C1Cl.ClC1=C(Cl)C(Cl)(Cl)C(Cl)=C1Cl LYMBWJDBLCMHBO-UHFFFAOYSA-N 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical class NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 235000019239 indanthrene blue RS Nutrition 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 150000003951 lactams Chemical class 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229940018564 m-phenylenediamine Drugs 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- NTNWKDHZTDQSST-UHFFFAOYSA-N naphthalene-1,2-diamine Chemical compound C1=CC=CC2=C(N)C(N)=CC=C21 NTNWKDHZTDQSST-UHFFFAOYSA-N 0.000 description 1
- KYTZHLUVELPASH-UHFFFAOYSA-N naphthalene-1,2-dicarboxylic acid Chemical compound C1=CC=CC2=C(C(O)=O)C(C(=O)O)=CC=C21 KYTZHLUVELPASH-UHFFFAOYSA-N 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical compound N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 description 1
- 238000012643 polycondensation polymerization Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 229960004889 salicylic acid Drugs 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 239000001038 titanium pigment Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- NFMWFGXCDDYTEG-UHFFFAOYSA-N trimagnesium;diborate Chemical compound [Mg+2].[Mg+2].[Mg+2].[O-]B([O-])[O-].[O-]B([O-])[O-] NFMWFGXCDDYTEG-UHFFFAOYSA-N 0.000 description 1
- XZZNDPSIHUTMOC-UHFFFAOYSA-N triphenyl phosphate Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)(=O)OC1=CC=CC=C1 XZZNDPSIHUTMOC-UHFFFAOYSA-N 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Classifications
-
- 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
- D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/22—Evaporating by bringing a thin layer of the liquid into contact with a heated surface
- B01D1/222—In rotating vessels; vessels with movable parts
-
- 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
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/08—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino-carboxylic acids
- C08G69/14—Lactams
- C08G69/16—Preparatory processes
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Polyamides (AREA)
Abstract
The invention discloses a preparation method of polyamide 6 fiber, which comprises the steps of firstly polymerizing a mixture of caprolactam, water and a molecular weight regulator in a polymerization reactor to prepare a polyamide 6 basic melt, then carrying out tackifying reaction and devolatilization on the polyamide 6 basic melt through an external falling film devolatilization reactor, and finally spinning and forming. According to the invention, the rheological property of the polyamide 6 melt is matched by designing the outside-tube falling film devolatilization reactor, so that the polyamide 6 melt is made into film flow under the driving of gravity, and the polymerization reaction dynamics and the molecular thermodynamic motion law are coupled, so that the controllable increase of the viscosity of the polyamide 6 melt and the efficient removal of volatile matters are realized. The relative viscosity of the prepared polyamide 6 melt is 2.20-2.90, the content of hot water extractables is less than or equal to 1.5wt%, and the average breaking strength of the fiber prepared by spinning is more than or equal to 4.0cN/dtex. Compared with slice spinning, the invention omits production processes of granulating, hot water extraction, drying and remelting, and has the characteristics of high efficiency, low energy consumption and the like, and has remarkable advantages in the aspects of economy and environmental protection.
Description
Technical Field
The invention belongs to the technical field of synthetic fiber preparation, and relates to a melt direct spinning preparation method of polyamide 6 fiber.
Technical Field
Polyamide 6 fibers are widely used in the fields of clothing, home textiles, electronic appliances, military industry, automobiles, etc. because of their outstanding physicochemical (wear resistance, hygroscopicity, fatigue resistance, spinnability, dyeability, etc.) properties, with the yield being that of the second synthetic fibers. In recent years, the production technology of the domestic polyamide 6 industry is continuously advanced, and especially the domestic self-supply rate of the main raw material caprolactam is greatly improved, the import dependence is continuously reduced, and the product cost is greatly reduced, so that the application of the caprolactam in the daily life fields of clothing, decoration, home textile and the like is continuously expanded. Although polyamide 6 fibers are rapidly developed in recent years, the industrial production still adopts slice spinning, and the problems of long process flow, high production energy consumption, large equipment investment and the like exist, so that the development of efficient low-carbon preparation technology is urgently needed.
At present, polyamide 6 fibers have not been melt spun for technical reasons. Compared with slice spinning, the melt direct spinning has the advantages of reducing the production processes of casting belt, granulating, hot water extraction, drying, remelting and the like, reducing equipment investment, obviously improving production efficiency and reducing production cost. The melt direct spinning of the polyamide 6 has obvious advantages from the aspects of economy and environmental protection, and is an important direction for the preparation of the polyamide 6 fiber material to develop to low energy consumption and high efficiency. To achieve direct spinning of polyamide 6 fiber melt, it is critical to directly prepare a polyamide 6 melt that can be used for spinning. The synthetic process routes for polyamide 6 can be classified into hydrolytic polymerization, anionic polymerization and solid-phase polymerization, depending on the polymerization mechanism. The hydrolysis polymerization of polyamide 6 takes water as an initiator, and raw material caprolactam is subjected to ring opening reaction, polyaddition and polycondensation reaction in a VK tube reactor to generate polyamide 6 with high molecular weight, and the polyamide 6 has narrow molecular weight distribution due to controllable reaction and mature technology, thus being a method commonly adopted in the industry at present.
In the hydrolytic polymerization of polyamide 6, the ring opening, polyaddition and polycondensation reactions of caprolactam are all reversible equilibrium reactions, and when the reaction reaches equilibrium, the conversion of caprolactam is generally about 90%, which means that about 10% of low molecular substances remain in the polymer melt (wherein caprolactam monomer is about 85% and oligomer is about 15%).
Since the melt of polyamide 6 prepared by hydrolysis and polymerization of caprolactam contains about 10% of low molecular substances, the melt cannot be directly spun. At present, the industrial solutions are: cooling and granulating the polyamide 6 melt obtained by hydrolytic polymerization, immersing the slices in circulating hot water, extracting low-molecular substances in the slices, and finally drying the extracted slices and then carrying out melt spinning. The energy consumption for hot water extraction is about 15-20% of the whole polymerization process, the time required for the hot water extraction is more than 2 times of that for hydrolytic polymerization, and a large amount of wastewater is additionally treated. The method has the advantages of long process flow, large equipment investment and high process energy consumption, remarkably increases the production cost of the polyamide 6 fiber and is not environment-friendly. Therefore, development of a novel polymerization device and a polymerization process method are urgently needed, the problem of gas phase extraction of low molecular substances in a high viscosity complex system is solved, and low molecular substances such as monomers, oligomers and the like are directly removed in the melt polymerization process of polyamide 6, so that the requirement of direct melt spinning is met.
The invention comprises the following steps:
aiming at the defects of the prior art, the invention provides a melt direct spinning preparation method of polyamide 6 fibers, which is characterized in that a falling film devolatilization reactor outside a pipe is designed to be matched with the rheological property of polyamide 6 melt materials, so that the polyamide 6 melt flows along the outer wall of a falling film pipe under the drive of gravity to form a film, the polymerization reaction dynamics and the molecular thermodynamic movement law are coupled, the condensation polymerization reaction controllability and the efficient removal of monomers and oligomers in the falling film process are finally realized, the polyamide 6 melt capable of being directly spun is obtained, and the polyamide 6 fibers are prepared in a large scale.
The technical scheme of the invention is as follows: a method for preparing polyamide 6 fibers, comprising the steps of:
(1) Mixing the basic components of caprolactam, water and a molecular weight regulator in proportion, preheating, continuously injecting into a VK tube reactor, carrying out hydrolysis ring opening, addition and polycondensation reaction, and discharging to obtain the polyamide 6 basic melt with the relative viscosity of 1.8-2.60.
(2) Conveying the polyamide 6 basic melt to the upper part of a falling film devolatilization reactor outside a pipe by using a pipeline, and performing falling film reaction outside the falling film pipe after being distributed by a film distributor; the outside-tube falling film devolatilization reactor is connected with a vacuum extraction system to efficiently remove caprolactam and oligomers in the polymer melt; the bottom of the falling film devolatilization reactor outside the pipe is a cone, a stirrer is arranged in the cone and used for uniformly material and cleaning the wall surface of the cone, and then the polyamide 6 melt with the relative viscosity of 2.20-2.90 and the hot water extractables content of less than or equal to 1.5wt% is prepared by discharging.
(3) And conveying the polyamide 6 melt to a spinning box body by a pipeline for spinning to obtain the polyamide 6 fiber.
The method comprises the following specific processes: firstly, adding caprolactam, water and a molecular weight regulator serving as basic components into a batching kettle in proportion, heating and stirring, preheating uniformly mixed raw materials by a preheater, continuously injecting the raw materials into a VK tube polymerization reactor, and performing plug flow on the raw materials from top to bottom in the tube reactor to generate caprolactam hydrolysis polymerization reaction; the caprolactam is subjected to ring opening under the action of ring opening agent water to generate aminocaproic acid, the aminocaproic acid is subjected to addition reaction to open the caprolactam, short-chain polymers are formed, and finally, polycondensation reaction is carried out between the short-chain polymers to generate long-chain polymers; according to the hydrolysis polymerization mechanism of caprolactam, ring opening and addition reaction mainly occur at the upper section of the VK pipe, and polycondensation reaction mainly occurs at the lower end of the VK pipe; the ring-opening rate of caprolactam is improved by controlling the water ratio, the reaction temperature and the pressure of the ring-opening agent, and in addition, the base melt viscosity of the polyamide 6 obtained by hydrolytic polymerization is cooperatively controlled by controlling the residence time of materials at the lower end of the VK pipe and the addition amount of a molecular weight regulator; finally preparing the polyamide 6 base melt with the relative viscosity of 1.80-2.60.
The relative viscosity of the prepared polyamide 6 basic melt is 1.80-2.60, and the hot water extractables content is less than or equal to 12wt%.
Conveying a polyamide 6 basic melt obtained by hydrolytic polymerization to the upper part of a falling film devolatilization reactor outside a pipe by using a pipeline, distributing the melt material by a film distributor, and making the melt material into film flow along the outer wall surface of the falling film pipe by gravity driving, and simultaneously carrying out devolatilization and polycondensation reaction; the film falling pipe structure is designed to be matched with the rheological property of the polyamide 6 basic melt, so that the melt material always meets the combination of larger film forming area and faster surface updating in the film falling process, the heat mass transfer efficiency in the high-viscosity melt is enhanced, and the polycondensation reaction and devolatilization requirements are met; the polycondensation reaction process is cooperatively controlled by regulating and controlling the falling film pipe structure, the end group content in the polyamide 6 basic melt, the residence time in the falling film process and the vacuum degree, and the high-efficiency removal of small molecular substances is ensured; the melt of the polyamide 6 after tackifying and devolatilizing is uniformly stirred by a stirrer at the bottom of the devolatilization reactor, and then the melt of the polyamide 6 which can be directly processed is obtained by discharging.
The relative viscosity of the prepared polyamide 6 melt is 2.20-2.90, and the hot water extractables content is less than or equal to 1.5wt%.
And directly conveying the melt of the polyamide 6 subjected to film-falling tackifying and devolatilization to different spinning positions by using a pipeline, and carrying out spinning forming after filtering to obtain the polyamide 6 fiber.
The average breaking strength of the obtained polyamide 6 fiber is more than or equal to 4.0cN/dtex, and the spinning stability is good.
On the basis of adopting the technical scheme, the invention can also adopt the following further technical scheme or use the following further technical scheme in combination:
the VK pipe reactor in the step (1) is a one-stage reactor, the reaction temperature is 240-275 ℃, the pressure is 0.05-0.3 MPa, and the reaction time is 15-24 hours.
The VK pipe reactor in the step (1) is a two-stage reactor, the reaction temperature of the pre-polymerizer is 240-275 ℃, the pressure is 0.05-0.3 MPa, and the reaction time is 2-10 hours; the reaction temperature of the post-polymerizer is 240-260 ℃, the pressure is-0.1-0.2 MPa, and the reaction time is 8-15 hours.
The reaction temperature of the outside-tube falling film devolatilization reactor in the step (2) is 240-280 ℃ and the vacuum degree is 20-650 Pa.
The falling film tube in the step (2) is a round tube, a corrugated tube or a special tube, the diameter or the maximum circumcircle diameter of the falling film tube is 5-100 mm, and the tube length is 3-15 m.
The spinning forming condition in the step (3) is that the spinning temperature is 245-280 ℃, and the spinning speed is 3000-6000 m/min.
In the step (1), the addition amount of the water is 0.5-5 wt% of caprolactam; the molecular weight regulator is one or a combination of more of organic monoacid, organic dibasic acid, monoamine and diamine, and the addition amount is 0-0.8 wt% of caprolactam.
The organic acid is aliphatic H (CH) 2 ) n COOH, wherein n=1 to 10; or aromatic, benzoic acid or naphthoic acid.
The monoamine is aliphatic H (CH) 2 ) m NH 2 Wherein m=1 to 10; or aromatic, aniline.
The organic dibasic acid is aliphatic dibasic acid HOOC (CH) 2 ) X COOH, wherein x=1 to 20; or aromatic dibasic acid, which is terephthalic acid, phthalic acid, isophthalic acid or naphthalene dicarboxylic acid; the diamine is aliphatic diamine H 2 N(CH 2 ) X NH 2 Wherein x=1 to 10; or aromatic diamine, which is p-phenylenediamine, naphthalene diamine, m-phenylenediamine, o-phenylenediamine or xylene diamine.
The sufficient hydrolysis ring-opening reaction of caprolactam in the VK polymerization tube is ensured by the addition amount of water, the reaction temperature and the reaction pressure, the caprolactam conversion rate is improved, and the content of monomers and oligomers in a melt is reduced. Although the improvement of the water content is favorable for caprolactam ring-opening reaction, excessive water can promote the increase of short-chain oligomers in the melt, which is unfavorable for the later molecular chain growth reaction and narrow distribution; the high temperature is favorable for ring opening reaction, but the high temperature can promote the back biting reaction of the terminal amino group on the linear chain, increase the content of the cyclic oligomer in the reaction system, and the cyclic oligomer has high melting point and is more difficult to devolatilize; the carboxyl or amino in the molecular weight regulator can react with the terminal amino or terminal carboxyl of the short-chain polymer and the long-chain polymer to consume the active reactive groups on the polymer chain, thereby inhibiting the polycondensation reaction, preventing excessive polycondensation in the falling film process from causing excessive material viscosity and widening the molecular weight distribution, and reducing the melt quality.
In the step (1), besides the basic components, caprolactam and oligomer recycled materials obtained in the step (2) through the vacuum extraction system or recycled materials after depolymerization can be added.
After condensing the extracted gas mixture, the obtained caprolactam and the oligomer can be used as the basic raw materials in the step (1) together for recycling, or the oligomer is depolymerized into caprolactam monomers and then used as the basic raw materials in the step (1) for recycling.
In the step (1), one or more of comonomer, catalyst, delustrant, antioxidant, anti-ultraviolet agent, colorant and flame retardant can be added according to the product requirement besides the basic component.
The comonomer is: one or more of aliphatic diamine, aliphatic diacid, aromatic diamine, aromatic diacid, hexamethylenediamine salt, linear amino acid, lactam, and lactone; the catalyst is NH 2 (CH 2 ) x One or more of COOH and nylon 66 salt, wherein X is 2-8; the delustrant is titanium dioxide; the antioxidant is one or more of antioxidant 1010, antioxidant 168 or antioxidant 616; the anti-ultraviolet agent is one or more of salicylic acid, zinc oxide, calcium carbonate and SEED; the colorant is one or more of phthalocyanine blue, phthalocyanine green, macromolecular red, macromolecular yellow, permanent violet, permanent yellow, azo red, titanium pigment, carbon black, pigment red 179, pigment blue 60, pigment green 36, pigment yellow 214, pigment orange 43, pigment brown 41, solvent violet 59, solvent violet 37, solvent red 143, solvent red 181, solvent blue 94, solvent green 29 and solvent yellow 135; the flame retardant comprises the following components: tetrabromobisphenol A, zinc borate, magnesium borate, bis (hexachlorocyclopentadiene) cyclooctane, triphenyl phosphate, red phosphorus, organic phosphate, ammonium polyphosphate, zinc borate, decaOne or more of bromodiphenyl ethers.
In the step (2), the external falling film devolatilization reactor comprises a vertical kettle body, a film distributor, a falling film pipe, a stirrer and a heating medium system, wherein the bottom of the external falling film devolatilization reactor is a cone, and the stirrer is arranged in the cone and used for uniformly feeding materials and cleaning the wall surface of the cone.
In the step (2), the vacuum extraction system comprises a condensation system and a vacuum system; the condensing system comprises one or more volatile component condensing towers connected in series or in parallel, a gas mixture composed of caprolactam, oligomers and other volatile matters extracted from melt is collected after condensation in the process of moving from bottom to top through an air inlet of the condensing tower, and the residual gas is discharged after condensation treatment; the vacuum system comprises a vacuum buffer tank and a vacuum pump; the vacuum pump comprises one or more of a rotary vane vacuum pump, a molecular vacuum pump, an ejector vacuum pump, a diffusion ejector pump, a water ring vacuum pump, a Roots vacuum pump, a screw vacuum pump and a reciprocating vacuum pump.
The polyamide 6 melt involves complex endothermic and exothermic processes such as chemical reactions, phase transition of substances and the like in the falling film flowing process of high temperature and high vacuum, so that the temperature of the whole and part of the film melt needs to be precisely controlled. The jacket type falling film kettle and the sleeve type falling film pipe structure are designed, so that a heating medium circulation mode is optimized, the heat of the melt at each stage of falling film devolatilization is supplemented or released, and the requirements of polycondensation reaction and devolatilization on temperature are met.
The reactor for devolatilizing the falling film outside the pipe provided by the invention is provided with a high-efficiency vacuum extraction system and a multi-stage condensation system, so that the high and stable vacuum degree in the falling film implementation process is ensured, and the condition that a large amount of small molecular substances are continuously removed and separated out of a reaction system in the continuous falling film process is satisfied. More advantageously, oligomers in the melt of polyamide 6 are more easily vaporized and extracted in the presence of other low boiling substances such as caprolactam, water, etc. during the falling film process; the low molecular substances such as caprolactam, water and the like wet the extraction pipeline and the condensing system, and prevent the precipitation and enrichment of the oligomer molecules on the solid wall surface in the extraction system.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts the straight-through method to directly prepare the polyamide 6 fiber in a large scale, omits the production processes of casting belts, granulating, hot water extraction, drying, remelting and the like, has the advantages of short production process, small equipment investment, high production efficiency and the like, and has obvious advantages in the aspects of economy and environmental protection.
2. The technology of the invention improves the film forming efficiency of the polyamide 6 melt by designing the falling film devolatilization reactor, strengthens the heat and mass transfer of the polyamide 6 melt, regulates and controls the melt flow process to meet the plug flow so as to adapt to the melt characteristics of viscosity change, realizes the controllable polycondensation and viscosity increase of the polyamide 6 melt, and simultaneously completes the efficient removal of caprolactam and oligomers to obtain the melt which can be directly spun and formed.
3. On the basis of fully researching and knowing the flow characteristic, polymerization reaction characteristic, mass transfer characteristic and coupling mechanism of the polyamide 6 melt, the structure of the falling film tube and the implementation process condition are optimized so as to adapt to the melt characteristic of viscosity change, and the one-stage or two-stage VK tube hydrolysis polymerization reactor which is mainstream in the industry at present can be connected before the falling film devolatilization reactor, so that the preparation method is convenient for industrialized implementation and popularization.
4. The falling film devolatilization reactor designed by the method has high-efficiency devolatilization function, and complex components consisting of high boiling point and multiphase substances in the polyamide 6 melt are extracted by gas phase to the greatest extent. The invention solves the problem that the oligomer with obvious influence on the processing stability and continuity is difficult to remove by utilizing the following rules: in the presence of water, caprolactam and other low-boiling-point azeotropic substances, regulating and controlling a falling film flow field to promote the low-boiling-point substances in the melt to be easily vaporized and nucleated, thereby promoting the high-boiling-point cyclic oligomer in the melt to be co-vaporized; in addition, volatile substances such as caprolactam, water and the like wet an extraction pipeline and a condensing system, and caprolactam and water can better dissolve oligomers at high temperature, so that vaporized oligomer molecules are prevented from being separated and enriched on a solid wall surface.
Description of the drawings:
fig. 1 and fig. 2 are schematic diagrams of a production flow for directly preparing polyamide 6 fibers by melt direct spinning, wherein fig. 1 is a production process flow of a one-stage VK tube polymerization superposition falling film devolatilization reaction, and fig. 2 is a production process flow of a two-stage VK tube polymerization superposition falling film devolatilization reaction.
In fig. 1, 1 is a material meter, 2 is a mixer, 3 is a transfer pump, 4 is a preheater, 5 is a one-stage VK tube polymerization reactor, 6 and 10 are melt transfer pumps, 7 is a falling film devolatilization reactor, 8 is a condensing system, 9 is a vacuum system, 11 is a melt filter, 12 is a spinning box, 13 is a drawing device, and 14 is a winding device.
Wherein, falling film devolatilization reactor includes: 7-1 of a vertical kettle body of a falling film devolatilization reactor, 7-2 of a melt cavity, 7-3 of a film distributor, 7-4 of a falling film pipe, 7-5 of a melt material stirrer, 7-6 of a heat medium inlet and 7-7 of a heat medium outlet; 8-1, 8-2 and 8-3 are condensation systems which can be designed into one stage, two stages or multiple stages (three to six stages) according to production requirements, and high vacuum degree in the falling film devolatilization reactor is maintained.
In fig. 2, 1 is a material meter, 2 is a mixer, 3 is a transfer pump, 4 is a preheater, 5 is a first stage VK tube polymerization reactor, 6, 10 and 16 are melt transfer pumps, 15 is a second stage VK tube polymerization reactor, 7 is a falling film devolatilization reactor, 8 is a condensing system, 9 is a vacuum system, 11 is a melt filter, 12 is a spinning manifold, 13 is a drawing device, and 14 is a winding device.
Wherein 5 and 15 are combined into a two-section type VK tube polymerization reactor, wherein the second section of the VK tube polymerization reactor of 15-1 comprises a kettle body, a 15-2 heat exchanger, a 15-3 collecting tank, a 15-4 buffer tank and a 15-5 vacuum pump; the falling film devolatilization reactor comprises: 7-1 of a vertical kettle body of a falling film devolatilization reactor, 7-2 of a melt cavity, 7-3 of a film distributor, 7-4 of a falling film pipe, 7-5 of a melt material stirrer, 7-6 of a heat medium inlet and 7-7 of a heat medium outlet; 8-1, 8-2 and 8-3 are condensation systems which can be designed into one stage, two stages or multiple stages (three to six stages) according to production requirements, and high vacuum degree in the falling film devolatilization reactor is maintained.
The specific embodiment is as follows:
the preparation method of the polyamide 6 fiber provided by the invention comprises the following steps:
(1) Mixing basic components of caprolactam, water and a molecular weight regulator in proportion, preheating, continuously injecting into a VK tube reactor, performing hydrolysis ring opening, addition and polycondensation reaction, and discharging to obtain a polyamide 6 basic melt with the relative viscosity of 1.80-2.6;
(2) Conveying the polyamide 6 basic melt to the upper part of a falling film devolatilization reactor outside a pipe by using a pipeline, and performing falling film reaction outside the falling film pipe after being distributed by a film distributor; the outside-tube falling film devolatilization reactor is connected with a vacuum extraction system to efficiently remove caprolactam and oligomers in the polymer melt; the lower part of the falling film devolatilization reactor outside the pipe is provided with a stirrer for uniform material, and then the material is discharged to prepare polyamide 6 melt with the relative viscosity of 2.20-2.90 and the hot water extractables content of less than or equal to 1.5 wt%;
(3) And conveying the polyamide 6 melt to a spinning box body by a pipeline for spinning to obtain the polyamide 6 fiber.
Preferably, in step (1): the addition amount of the water is 0.5-5 wt% of caprolactam; the molecular weight regulator is one or a combination of more of organic monoacid, organic dibasic acid, monoamine and diamine, and the addition amount is 0-0.8 wt% of caprolactam; stirring at a rotating speed of 50-200 r/min for 10-60 min at the mixing temperature of 80-150 ℃; in addition to the basic components, one or more of comonomer, catalyst, delustrant, antioxidant, anti-ultraviolet agent, colorant and flame retardant can be added according to the requirements of the product;
in the step (1), when the VK pipe reactor is a one-stage reactor, the reaction temperature is 240-275 ℃, the pressure is 0.05-0.3 MPa, and the reaction time is 15-24 hours; when the VK pipe reactor is a two-stage reactor, the reaction temperature of the pre-polymerizer is 240-275 ℃, the pressure is 0.05-0.3 MPa, the reaction time is 2-10 hours, the reaction temperature of the post-polymerizer is 240-260 ℃, the pressure is-0.1-0.2 MPa, and the reaction time is 8-15 hours.
The relative viscosity of the base melt of the polyamide 6 prepared in the step (1) is 1.80-2.60, and the content of hot water extractables is less than or equal to 12wt%.
Preferably, in step (2): the reaction temperature of the falling film devolatilization reactor outside the pipe is 240-280 ℃ and the vacuum degree is 20-650 Pa;
the relative viscosity of the prepared polyamide 6 melt is 2.20-2.90, and the hot water extractables content is less than or equal to 1.5wt%.
Preferably, in step (3): the spinning forming condition is that the temperature is 245-280 ℃ and the speed is 3000-6000 m/min.
The average breaking strength of the obtained polyamide 6 fiber is more than or equal to 4.0cN/dtex, and the spinning stability is good.
The properties of the product obtained by implementing the method are measured according to the following standard method: the relative viscosity of the polyamide 6 melt and the hot water extractables content value are measured according to national standard GB/T38138-2019; the average breaking strength value of the polyamide 6 fiber is measured according to national standard GB/T14344-2008.
The method is realized by a device shown in the attached figure 1 or the attached figure 2, and the device mainly comprises a metering tank, a batching kettle, a one-section or two-section VK tube polymerization reactor, a falling film devolatilization reactor, a spinning device, a drafting device and a winding device.
The VK tubular polymerizer is a one-stage polymerizer or a two-stage polymerizer which are mature in the industry at present; the viscosity of the basic melt, the composition of the oligomer and the content of the oligomer are regulated and controlled by controlling the caprolactam hydrolysis polymerization implementation process.
The external falling film devolatilization reactor comprises a vertical kettle body, a film distributor, a falling film pipe, a stirrer and a heating medium system; the jacket of the vertical kettle body is internally provided with a heating medium, so that the vertical kettle has a heat preservation function, and the film distributor and the film dropping pipe are internally provided with the heating medium, so that the temperature of a melt can be maintained stable; the falling film pipe is a circular pipe, a corrugated pipe or a special pipe, the diameter or the maximum circumcircle diameter of the falling film pipe is 5-100 mm, the pipe length is 3-15 m, the shape and the size of the falling film pipe can be optimized to adapt to the rheological property of the VK pipe discharging base melt, the combination of a larger film forming area and a faster surface updating time is always realized by regulating and controlling the falling film flow of the base melt, the requirements of polycondensation reaction and micromolecule removal in a high-viscosity melt on heat mass transfer are met, and in addition, the controllable polycondensation reaction and micromolecule efficient removal are realized by regulating and controlling the stay time of the falling film process of the base melt; the stirrer can homogenize the high-viscosity materials after falling film devolatilization, and simultaneously continuously shear the high-viscosity materials on the inner wall surface of the bottom of the falling film kettle to prevent the materials from adhering to the wall and coking.
To accomplish the purpose of high-efficiency devolatilization and polycondensation and adhesion enhancement in high-viscosity melt, the external falling film devolatilizer must be connected with a high-efficiency extraction system, and only a large amount of volatile matters in the falling film processing process are timely and effectively extracted, cooled and separated, the high vacuum degree in the falling film process can be maintained, so that the continuous removal of small molecular substances in the melt is realized; the high-efficiency extraction system comprises a condensation system and a vacuum system; the condensing system comprises one or more volatile component condensing towers which are connected in series or in parallel, and a gas mixture composed of caprolactam, oligomers and other volatile matters extracted from the melt is converted into liquid and collected after full heat exchange in the process of moving from bottom to top through an air inlet of the condensing tower; the vacuum extraction system comprises a vacuum buffer tank and a vacuum pump; the vacuum pump comprises one or more of a rotary vane vacuum pump, a molecular vacuum pump, an ejector vacuum pump, a diffusion ejector pump, a water ring vacuum pump, a Roots vacuum pump, a screw vacuum pump and a reciprocating vacuum pump.
The present invention is further illustrated by the following specific examples, which are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention; in addition, after reading the content of the invention, the person skilled in the art makes various modifications, alterations and equivalent substitutions to the invention, and the invention still belongs to the protection scope of the technical scheme of the invention.
Example 1
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.47 and a hot water extractables content of 0.73% by weight.
Example 2
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 5m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.39 and a hot water extractables content of 1.49% by weight.
Example 3
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 100mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.41 and a hot water extractables content of 1.27% by weight.
Comparative example 1
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film pipe is 120mm, and the length is 2m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.24 and a hot water extractables content of 3.29% by weight.
Comparing the implementation results of comparative example 1 with those of examples 1-3, it is known that when the length of the falling film pipe is less than 3m, the average residence time of the polyamide 6 melt material in the falling film reactor is short, the total heat and mass transfer amount in the process is low, and the devolatilization effect is poor; when the pipe diameter of the falling film pipe is too large, the film forming flowing form and the controllability of the material on the falling film pipe are poor, and the falling film devolatilization effect is poor; when the length of the film-falling pipe is continuously increased, although the average residence time of the polyamide 6 melt material is prolonged, the melt polycondensation viscosity increasing range is limited, and the excessive residence time is easy to cause side reactions such as branching, end-group and the like, thereby influencing the melt quality after film-falling viscosity increasing and the subsequent melt spinning.
Example 4
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 268 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.44 and a hot water extractables content of 0.98% by weight.
Comparative example 2
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 235 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.25 and a hot water extractables content of 3.47% by weight.
Comparative example 3
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 285 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.31 and a hot water extractables content of 1.55% by weight.
Comparing the implementation results of comparative examples 2 and 3 with those of examples 1 and 4, it is clear that the lower falling film temperature leads to higher melt viscosity of the polyamide 6 and poorer falling film fluidity; on the other hand, the low temperature is not favorable for vaporizing small molecular substances in the high-viscosity melt, and the two reasons cause that the devolatilization effect of the falling film can not meet the requirement; in addition, when the processing temperature is higher than 280 ℃, side reactions such as thermal degradation, branching and the like of the high Wen Cujin polyamide 6 melt occur, so that the melt is easy to yellow, the quality of the polyamide 6 melt after falling film devolatilization is poor, and further the subsequent spinning forming is affected.
Example 5
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 650Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is two-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.40 and a hot water extractables content of 1.23% by weight.
Example 6
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 50Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is four stages connected in series; the polyamide 6 melt obtained had a relative viscosity of 2.63 and a hot water extractables content of 0.65% by weight.
Comparative example 4
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 22 hours; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 1000Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the condensation system is adopted as a first stage; the polyamide 6 melt obtained had a relative viscosity of 2.32 and a hot water extractables content of 2.19% by weight.
Comparing the implementation results of comparative example 4 with examples 1, 5 and 6, it is known that the vacuum degree significantly affects the film falling and devolatilization effects of the polyamide 6 melt, and when the vacuum degree is lower than 650Pa, the mass transfer efficiency in the film falling process is poor, and small molecular substances cannot be vaporized and separated in time; the high vacuum degree obviously improves the falling film devolatilization efficiency, the higher the condensing system stage number is, the higher the obtained vacuum degree is, but the higher the stage number is, the equipment investment and the maintenance cost are increased.
Example 7
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0.4wt%; adopting a one-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature is 268 ℃, the polymerization reaction temperature is 265 ℃, the reaction pressure is 0.2MPa, and the reaction time is 19h; the relative viscosity of the prepared polyamide 6 basic melt is 2.20, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion and devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.45 and a hot water extractables content of 1.36% by weight.
Example 8
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 0wt%; adopting a two-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature of a pre-polymerizer is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction time is 9h, the reaction pressure is 0.2MPa, the reaction temperature of a post-polymerizer is 260 ℃, the reaction time is 10h, and the reaction pressure is 0MPa; the relative viscosity of the prepared polyamide 6 basic melt is 2.56, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion promotion and falling film devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 2.93 and a hot water extractables content of 1.15% by weight.
Comparative example 5
The first step: mixing caprolactam, water and terephthalic acid in a proportioning kettle according to a proportion, wherein the mixing temperature is 85 ℃, the stirring time is 60min, and filtering, preheating and conveying the mixture to a feed inlet of a VK kettle after uniform mixing; wherein, the addition amount of water is 2wt% relative to caprolactam, and the addition amount of terephthalic acid is 1.0wt%; adopting a two-stage VK tube reactor, wherein the hydrolysis ring-opening reaction temperature of a pre-polymerizer is 253 ℃, the polymerization reaction temperature is 265 ℃, the reaction time is 9h, the reaction pressure is 0.2MPa, the reaction temperature of a post-polymerizer is 260 ℃, the reaction time is 10h, and the reaction pressure is 0MPa; the relative viscosity of the prepared polyamide 6 basic melt is 1.77, and the hot water extractables content is less than or equal to 12wt%.
And a second step of: conveying the polyamide 6 basic melt prepared in the first step to an out-pipe falling film devolatilization reactor for falling film adhesion promotion and falling film devolatilization, wherein the devolatilization temperature is 255 ℃ and the vacuum degree is 200Pa; the diameter of the circumscribed circle of the adopted falling film tube is 80mm, and the length is 8m; the adopted condensation system is three-stage series connection; the polyamide 6 melt obtained had a relative viscosity of 1.86 and a hot water extractables content of 1.87% by weight.
Comparing the implementation results of comparative example 5 with those of examples 1, 7 and 8, when the addition amount of terephthalic acid as a molecular weight regulator is more than 0.8wt%, the melt polycondensation reaction is obviously inhibited, the viscosity increasing amplitude of the falling film is obviously reduced, and the content of linear oligomer in the basic melt is increased so that the hot water extractable content in the melt is also increased after the falling film is devolatilized; when the hydrolysis polymerization temperature in the VK pipe is higher, caprolactam is easy to cyclize into cyclic oligomers, so that the content and the composition of the oligomers in the base melt of the polyamide 6 are increased, and the devolatilization effect of the falling film is further affected. The quality of the polyamide 6 base melt obviously influences the viscosity-increasing and devolatilizing effects of the falling film, and the hydrolytic polymerization process of caprolactam in a VK pipe needs to be optimized, so that the obtaining of the base melt favorable for the viscosity-increasing and devolatilizing of the falling film is important.
Example 9
Conveying the melt of the polyamide 6 prepared in the example 1 to a spinning box body by using a pipeline for spinning, wherein the spinning temperature is 260 ℃ and the spinning speed is 4200m/min; the average breaking strength of the prepared polyamide 6 fiber is 4.5cN/dtex, and the spinning stability is good.
Example 10
Conveying the melt of the polyamide 6 prepared in the example 8 to a spinning box body by using a pipeline for spinning, wherein the spinning temperature is 260 ℃ and the spinning speed is 4200m/min; the average breaking strength of the prepared polyamide 6 fiber is 5.3cN/dtex, and the spinning stability is good.
Comparative example 6
Conveying the melt of the polyamide 6 prepared in the comparative example 1 to a spinning box body by using a pipeline for spinning, wherein the spinning temperature is 260 ℃ and the spinning speed is 4200m/min; the average breaking strength of the prepared polyamide 6 fiber is 3.1cN/dtex, and the spinning stability is poor.
Comparative example 7
Conveying the polyamide 6 melt prepared in the comparative example 3 to a spinning box body by using a pipeline for spinning, wherein the spinning temperature is 260 ℃ and the spinning speed is 4200m/min; the average breaking strength of the polyamide 6 fiber obtained was 3.5cN/dtex, and the spinning stability was general.
As is clear from comparison of the results of comparative examples 6 and 7 with examples 9 and 10, the devolatilization efficiency is high, the hot water extractables content in the melt is less than or equal to 1.5wt%, the spinning stability is good, and the strength of the obtained fiber is high.
Claims (10)
1. A method for preparing polyamide 6 fibers, characterized by comprising the following steps:
(1) Mixing basic components of caprolactam, water and a molecular weight regulator in proportion, preheating, continuously injecting into a VK tube reactor, performing hydrolysis ring opening, addition and polycondensation reaction, and discharging to obtain a polyamide 6 basic melt with the relative viscosity of 1.8-2.60;
(2) Conveying the polyamide 6 basic melt to the upper part of a falling film devolatilization reactor outside a pipe by using a pipeline, and performing falling film reaction outside the falling film pipe after being distributed by a film distributor; the outside-tube falling film devolatilization reactor is connected with a vacuum extraction system to efficiently remove caprolactam and oligomers in the polymer melt; discharging to obtain polyamide 6 melt with the relative viscosity of 2.20-2.90 and the hot water extractables content of less than or equal to 1.5 wt%;
(3) And conveying the polyamide 6 melt to a spinning box body by a pipeline for spinning to obtain the polyamide 6 fiber.
2. The method of manufacturing according to claim 1, wherein: the VK pipe reactor in the step (1) is a one-stage reactor, the reaction temperature is 240-275 ℃, the pressure is 0.05-0.3 MPa, and the reaction time is 15-24 hours.
3. The method of manufacturing according to claim 1, wherein: the VK pipe reactor in the step (1) is a two-stage reactor, the reaction temperature of the pre-polymerizer is 240-275 ℃, the pressure is 0.05-0.3 MPa, and the reaction time is 2-10 hours; the reaction temperature of the post-polymerizer is 240-265 ℃, the pressure is-0.1-0.2 MPa, and the reaction time is 8-15 hours.
4. The method of manufacturing according to claim 1, wherein: the reaction temperature of the outside-tube falling film devolatilization reactor in the step (2) is 240-280 ℃ and the vacuum degree is 20-650 Pa.
5. The method of manufacturing according to claim 1, wherein: the falling film tube in the step (2) is a round tube, a corrugated tube or a special tube, the diameter or the maximum circumcircle diameter of the falling film tube is 5-100 mm, and the tube length is 3-15 m.
6. The method of manufacturing according to claim 1, wherein: the spinning forming condition in the step (3) is that the spinning temperature is 245-280 ℃, and the spinning speed is 3000-6000 m/min.
7. The method of manufacturing according to claim 1, wherein: in the step (1), the addition amount of the water is 0.5-5 wt% of caprolactam; the molecular weight regulator is one or a combination of more of organic monoacid, organic dibasic acid, monoamine and diamine, and the addition amount is 0-0.8 wt% of caprolactam.
8. The method of manufacturing according to claim 1, wherein: in the step (1), besides the basic components, caprolactam and oligomer recycle materials obtained by extraction and condensation of the vacuum extraction system in the step (2) or recycle materials after depolymerization treatment are added.
9. The method of manufacturing according to claim 1, wherein: in the step (1), one or more of comonomer, catalyst, delustrant, antioxidant, anti-ultraviolet agent, colorant and flame retardant are added in addition to the basic component.
10. The method of manufacturing according to claim 1, wherein: in the step (2), the external falling film devolatilization reactor comprises a vertical kettle body, a film distributor, a falling film pipe, a stirrer and a heating medium system, wherein the bottom of the external falling film devolatilization reactor is a cone, and the stirrer is arranged in the cone and is used for uniformly feeding materials and cleaning the wall surface of the cone; the vacuum extraction system comprises a condensation system and a vacuum system; the condensing system comprises one or more volatile component condensing towers which are connected in series or in parallel; the vacuum system comprises a vacuum buffer tank and a vacuum pump; the vacuum pump comprises one or more of a rotary vane vacuum pump, a molecular vacuum pump, an ejector vacuum pump, a diffusion ejector pump, a water ring vacuum pump, a Roots vacuum pump, a screw vacuum pump and a reciprocating vacuum pump.
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