CN114619689B - Method for continuously preparing regenerated natural polymer film - Google Patents
Method for continuously preparing regenerated natural polymer film Download PDFInfo
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- CN114619689B CN114619689B CN202111552691.2A CN202111552691A CN114619689B CN 114619689 B CN114619689 B CN 114619689B CN 202111552691 A CN202111552691 A CN 202111552691A CN 114619689 B CN114619689 B CN 114619689B
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- 229920005615 natural polymer Polymers 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 73
- 238000004090 dissolution Methods 0.000 claims abstract description 44
- 239000000017 hydrogel Substances 0.000 claims abstract description 42
- 239000000701 coagulant Substances 0.000 claims abstract description 28
- 238000001035 drying Methods 0.000 claims abstract description 25
- 239000000499 gel Substances 0.000 claims abstract description 24
- 239000012528 membrane Substances 0.000 claims abstract description 24
- 238000004140 cleaning Methods 0.000 claims abstract description 22
- 238000007711 solidification Methods 0.000 claims abstract description 21
- 230000008023 solidification Effects 0.000 claims abstract description 21
- 239000002861 polymer material Substances 0.000 claims abstract description 18
- 230000001112 coagulating effect Effects 0.000 claims abstract description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 95
- 239000000243 solution Substances 0.000 claims description 79
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 71
- 229920002678 cellulose Polymers 0.000 claims description 57
- 239000001913 cellulose Substances 0.000 claims description 57
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 48
- 239000004202 carbamide Substances 0.000 claims description 33
- 239000002904 solvent Substances 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 238000004804 winding Methods 0.000 claims description 25
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 15
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 15
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 10
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 10
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 claims description 10
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims description 9
- 235000017491 Bambusa tulda Nutrition 0.000 claims description 9
- 241001330002 Bambuseae Species 0.000 claims description 9
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims description 9
- 239000011425 bamboo Substances 0.000 claims description 9
- 229920002101 Chitin Polymers 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000005711 Benzoic acid Substances 0.000 claims description 5
- 229920000742 Cotton Polymers 0.000 claims description 5
- IMQLKJBTEOYOSI-GPIVLXJGSA-N Inositol-hexakisphosphate Chemical compound OP(O)(=O)O[C@H]1[C@H](OP(O)(O)=O)[C@@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@@H]1OP(O)(O)=O IMQLKJBTEOYOSI-GPIVLXJGSA-N 0.000 claims description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- IMQLKJBTEOYOSI-UHFFFAOYSA-N Phytic acid Natural products OP(O)(=O)OC1C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C1OP(O)(O)=O IMQLKJBTEOYOSI-UHFFFAOYSA-N 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 5
- 235000010233 benzoic acid Nutrition 0.000 claims description 5
- 239000007789 gas Substances 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 239000000467 phytic acid Substances 0.000 claims description 5
- 229940068041 phytic acid Drugs 0.000 claims description 5
- 235000002949 phytic acid Nutrition 0.000 claims description 5
- 229920001661 Chitosan Polymers 0.000 claims description 4
- 229920001131 Pulp (paper) Polymers 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 claims description 4
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 claims description 3
- 241000609240 Ambelania acida Species 0.000 claims description 3
- 241001465754 Metazoa Species 0.000 claims description 3
- 235000014676 Phragmites communis Nutrition 0.000 claims description 3
- 239000010905 bagasse Substances 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 239000000661 sodium alginate Substances 0.000 claims description 3
- 235000010413 sodium alginate Nutrition 0.000 claims description 3
- 229940005550 sodium alginate Drugs 0.000 claims description 3
- 239000010902 straw Substances 0.000 claims description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 2
- 241000251555 Tunicata Species 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- QKSIFUGZHOUETI-UHFFFAOYSA-N copper;azane Chemical compound N.N.N.N.[Cu+2] QKSIFUGZHOUETI-UHFFFAOYSA-N 0.000 claims description 2
- 230000001172 regenerating effect Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 1
- 239000004627 regenerated cellulose Substances 0.000 abstract description 36
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000001125 extrusion Methods 0.000 description 15
- PTHCMJGKKRQCBF-UHFFFAOYSA-N Cellulose, microcrystalline Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC)C(CO)O1 PTHCMJGKKRQCBF-UHFFFAOYSA-N 0.000 description 9
- 230000015271 coagulation Effects 0.000 description 9
- 238000005345 coagulation Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 230000001276 controlling effect Effects 0.000 description 8
- 229920000875 Dissolving pulp Polymers 0.000 description 6
- 239000003513 alkali Substances 0.000 description 6
- 238000005266 casting Methods 0.000 description 6
- 239000012530 fluid Substances 0.000 description 6
- 238000004806 packaging method and process Methods 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 239000002585 base Substances 0.000 description 5
- 238000007602 hot air drying Methods 0.000 description 5
- 230000008929 regeneration Effects 0.000 description 5
- 238000011069 regeneration method Methods 0.000 description 5
- 238000002834 transmittance Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 230000002087 whitening effect Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 150000004676 glycans Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000002608 ionic liquid Substances 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- 229920001282 polysaccharide Polymers 0.000 description 2
- 239000005017 polysaccharide Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- FHVDTGUDJYJELY-UHFFFAOYSA-N 6-{[2-carboxy-4,5-dihydroxy-6-(phosphanyloxy)oxan-3-yl]oxy}-4,5-dihydroxy-3-phosphanyloxane-2-carboxylic acid Chemical compound O1C(C(O)=O)C(P)C(O)C(O)C1OC1C(C(O)=O)OC(OP)C(O)C1O FHVDTGUDJYJELY-UHFFFAOYSA-N 0.000 description 1
- 241000251557 Ascidiacea Species 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- 238000012425 Freezing-thawing process Methods 0.000 description 1
- LFTLOKWAGJYHHR-UHFFFAOYSA-N N-methylmorpholine N-oxide Chemical compound CN1(=O)CCOCC1 LFTLOKWAGJYHHR-UHFFFAOYSA-N 0.000 description 1
- 244000061176 Nicotiana tabacum Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- 229940072056 alginate Drugs 0.000 description 1
- 229920000615 alginic acid Polymers 0.000 description 1
- 235000010443 alginic acid Nutrition 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000007606 doctor blade method Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000010096 film blowing Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000010345 tape casting Methods 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D7/00—Producing flat articles, e.g. films or sheets
- B29D7/01—Films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/02—Cellulose; Modified cellulose
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
- C08J2305/08—Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Mechanical Engineering (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Moulding By Coating Moulds (AREA)
Abstract
The invention provides a method for continuously preparing a regenerated natural polymer film, which is carried out in a device comprising a dissolving unit (1), a solidifying unit (2) and a film post-treatment unit (7), and comprises the following steps: a. in a natural polymer material dissolution kettle (101), vacuum defoamation is carried out; b. the natural polymer solution enters a slot die head (201) and is injected into a coagulating bath (202), and is coagulated in a coagulant to obtain regenerated natural polymer gel; c. the regenerated natural polymer gel is prepared into regenerated natural polymer hydrogel through a drafting unit (3) and a cleaning unit (4); d. drying the regenerated natural polymer hydrogel to prepare a regenerated natural polymer membrane; the temperature difference between the dissolution unit (1) and the solidification unit (2) is less than or equal to 30 ℃. The method has high production efficiency and short time consumption, can be widely applied to natural polymer solution systems with different consistencies, and the prepared regenerated cellulose has accurate and controllable film thickness and width, and has uniform and flat film thickness.
Description
Technical Field
The invention relates to the field of membrane preparation, in particular to a method for continuously preparing a regenerated natural polymer membrane by slit extrusion.
Background
The natural polymer mainly comprises cellulose, chitin, chitosan, alginate and the like, wherein the cellulose is natural polymer polysaccharide with the most abundant reserves in the nature. The regenerated cellulose film is made of natural cellulose such as cotton pulp and wood pulp through viscose process. Unlike common paper, it is not only flexible, but also transparent like glass, so it is called "cellophane"; the packaging material is mainly applied to the fields of food packaging, tobacco packaging, medicine packaging, cosmetic packaging, firework packaging, express packaging and the like, and belongs to a low-carbon environment-friendly packaging material [ China paper-making journal society industry research center ]. [ China paper making, 38 (11).]. Natural polymers have extremely strong hydrogen bonding action between molecules and within molecules, so that they are insoluble in common solvents and are difficult to directly use. At present, the solvent for dissolving natural polymers mainly comprises NaOH/CS 2 LiCl/DMAc, ionic liquids, N-methylmorpholine-N-oxide and aqueous alkali/urea solvent systems, etc. Since the melting temperature of the natural polymer polysaccharide is less than the decomposition temperature thereof, the regenerated natural polymer film is usually produced by wet forming such as a unidirectional casting method, a doctor blade method, a blown film method, and the like.
For example, zhang et al use alkali/urea aqueous solvent to dissolve cotton linters, place the resulting cellulose solution on a smooth glass plate, uniformly scrape to a thickness of 1.0-3.0 mm with a doctor blade, then slowly shape with an ethanol/deionized water mixed solvent as a regenerative coagulation bath, and then air dry naturally to produce a transparent cellulose film excellent in mechanical properties [ Zhang, l.; ruan, d.; zhou, j. Ind. Eng. Chem. Res., 2001, 40, 5923-5928 ]. However, the unidirectional casting method and the knife coating method are long in time consumption and low in efficiency, slow solidification and shaping in a mild solidification bath are needed, waste of cellulose solution is difficult to avoid, and the method is suitable for laboratories.
CN105670026a discloses that an ionic liquid aqueous solution and a cellulose raw material are premixed, then vacuum dehydration, meshing at a higher temperature, dissolution and deaeration are carried out by using a screw extruder, a spray film is solidified and regenerated in water, and then the regenerated cellulose film is prepared through cleaning, plasticizing, drying and humidity adjustment. The extrusion molding method requires a high viscosity and a high solid content of a cellulose solution, and the cellulose solution needs to be as a polymer "melt", i.e., has special properties of being solidified by cooling and being changed into a liquid again by heating, so that the air blowing method in a coagulating bath can be used. The method is difficult to be applied to dilute cellulose solution with low molecular weight or low concentration, and the film thickness uniformity and rolling evenness of the film prepared by the film blowing method are poor, so that the method is not suitable for producing film products with high precision requirements.
Disclosure of Invention
The invention aims to solve the problems of long time consumption, low efficiency, limited application range, poor film thickness uniformity, poor flatness and the like in the prior art, and provides a method for rapidly and continuously preparing a cellulose film.
In order to achieve the above object, an aspect of the present invention provides a method for continuously producing a regenerated natural polymer film, the method comprising:
(1) Mixing and dissolving a natural polymer material and a solvent to obtain a natural polymer solution, and carrying out vacuum defoaming;
(2) The natural polymer solution is solidified in a coagulant to obtain regenerated natural polymer gel;
(3) Drawing and cleaning the regenerated natural polymer gel to prepare regenerated natural polymer hydrogel;
(4) Drying the regenerated natural polymer hydrogel to prepare a regenerated natural polymer membrane; winding is carried out through winding;
controlling the operation temperature difference between dissolution and solidification to be less than or equal to 30 ℃; preferably 20 ℃ or lower, more preferably 0 to 20 ℃; controlling the draft ratio of the regenerated natural polymer gel in the draft process to be 1:1-1:5.
In a second aspect of the present invention, a regenerated natural polymer film prepared according to the aforementioned preparation method.
Preferably, the thickness of the regenerated natural polymer film is 0.01-1 mm; preferably 0.03 to 0.1mm.
According to the method for continuously preparing the regenerated natural polymer film, provided by the invention, the natural polymer solution can be stably molded by controlling the regeneration of the natural polymer solution and the temperature before the regeneration of the natural polymer solution, so that the regenerated natural polymer film is ensured to be uniform and smooth.
The method for continuously preparing the regenerated natural polymer membrane has the advantages of high efficiency, accurate and controllable thickness and width of the hydrogel, and uniform and flat prepared regenerated natural polymer hydrogel.
The method for continuously preparing the regenerated natural polymer film provided by the invention has the advantages of high production efficiency, short time consumption, convenience in adjustment and optimization of each section of process, and wide application in natural polymer solution systems with different consistencies.
According to the method for continuously preparing the regenerated natural polymer membrane material, provided by the invention, the natural polymer solution is regenerated and the temperature difference before the regeneration of the natural polymer solution is controlled; the draft ratio of the regenerated natural polymer gel is controlled to be 1:1-1:5, so that the continuous preparation of the regenerated natural polymer film is realized, the regenerated cellulose film coiled material with the tensile strength of 181MPa and the elongation at break of 12% is obtained, the mechanical strength and the elongation at break are respectively 1.3 times and 1.1 times that of a casting method, and the whole process is completed within 4 hours, and the duration is 1/6 of that of the casting method.
Drawings
FIG. 1 is a schematic view showing the constitution of an apparatus for producing a regenerated cellulose membrane according to an embodiment of the present invention;
FIG. 2 is a front view of a slot die provided in an embodiment of the invention;
FIG. 3 is a cross-sectional view of a slot die of the present invention;
FIG. 4 is a stress-strain curve of a regenerated cellulose membrane;
fig. 5 is a surface SEM image of the regenerated cellulose membrane produced by extrusion.
Description of the reference numerals
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention relates to a method for continuously preparing a regenerated natural polymer film, which comprises the following steps:
(1) Mixing and dissolving a natural polymer material and a solvent to obtain a natural polymer solution, and carrying out vacuum defoaming;
(2) The natural polymer solution is solidified in a coagulant to obtain regenerated natural polymer gel;
(3) Drawing and cleaning the regenerated natural polymer gel to prepare regenerated natural polymer hydrogel;
(4) Drying the regenerated natural polymer hydrogel to prepare a regenerated natural polymer membrane; winding is carried out through winding;
controlling the operation temperature difference between dissolution and solidification to be less than or equal to 30 ℃; controlling the draft ratio of the regenerated natural polymer gel in the draft process to be 1:1-1:5.
According to the invention, the concentration of the natural polymer material in the natural polymer solution is 4-20wt%; the polymerization degree of the natural polymer material is 200-1000; the natural polymer material is at least one of cellulose, chitin, chitosan and sodium alginate.
According to the invention, the cellulose source is one or more of cotton linter pulp, wood pulp, bamboo pulp, straw pulp, bagasse pulp, reed pulp, ascidian cellulose and animal cellulose.
According to the present invention, the temperature difference between dissolution and solidification is controlled to 25℃or less, preferably 20℃or less, more preferably 0 to 20 ℃.
According to the present invention, preferably, the dissolution and solidification of the natural polymer solution are performed in an inert gas atmosphere; the inert gas atmosphere is CO 2 、N 2 A rare gas atmosphere; the natural polymer film prepared by dissolving and solidifying under the inert gas atmosphere has more excellent mechanical properties.
According to the invention, the solvent is sodium hydroxide solution, cuprammonium solution, naOH/CS 2 One or more of a solution, a base/urea solution, and a NaOH/thiourea solution; preferably a base/urea solution; more preferably, the base/urea solution is an aqueous NaOH and urea solution.
According to the present invention, preferably, the NaOH and urea aqueous solution components include: 4-8wt% of NaOH, 10-14wt% of urea and 78-85wt% of water.
According to the present invention, the coagulant contains one or more of pure water, methanol, ethanol, ethylene glycol, DMSO, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, citric acid, phytic acid, nitric acid, and benzoic acid; preferably an aqueous solution of 10 to 20% acid; more preferably 10 to 20wt% aqueous citric acid solution.
According to the invention, the drawing is carried out in the presence of a coagulant; the coagulant contains one or more of pure water, methanol, ethanol, ethylene glycol, DMSO, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, citric acid, phytic acid, nitric acid, and benzoic acid.
According to the invention, the drying temperature of the regenerated natural polymer hydrogel is 40-65 ℃; preferably, step-wise temperature-rising drying is employed.
According to the invention, the thickness of the regenerated natural polymer hydrogel is 0.01-3 mm; preferably 1-2 mm; and/or
According to the invention, the thickness of the regenerated natural polymer film is 0.01-1 mm; preferably 0.03 to 0.1mm.
The invention provides a method for continuously preparing a regenerated natural polymer film, which is carried out in a device comprising a dissolving unit 1, a solidifying unit 2 and a film post-treatment unit, as shown in figure 1:
the dissolving unit 1 is used for preparing natural polymer solution for preparing the film;
the solidification unit 2 comprises a slot die 201 and a solidification bath 202, wherein natural polymer solution is extruded from the slot die 201 and enters the solidification bath 202 to be solidified to prepare regenerated natural polymer gel;
the film post-treatment unit is used for cleaning, modifying, drying and rolling the regenerated natural polymer hydrogel to prepare a regenerated natural polymer film and comprises a drafting unit 3, a cleaning unit 4, a drying unit 5 and a winding unit 6;
as shown in fig. 2 and 3, the slot die 201 includes an upper die body 205, a lower die body 206, a fluid channel i 207, a fluid channel ii 208, a feed pipe 209, a die cavity 210, a lower die lip 211, and an upper die lip 213.
The upper die body 205 and the lower die body 206 are connected by fastening screws to form a slot die.
The feed pipe 209 is located in the lower die body 206 and is connected to the die cavity 210 for feeding the cellulose solution.
The mold cavity 210 is an internal recess of the lower mold body 206 for cellulose solution storage.
The front ends of the upper die body 205 and the lower die body 206 are respectively provided with an upper die lip 213 and a lower die lip 211 along the length direction, and the gap between the die lips is used as a discharge port of the slot die 201.
The gap between the upper die lip 213 and the lower die lip 211 is adjustable in size by movement of the lower die lip 211 in the vertical direction.
The upper die body 205 and the lower die body 206 are respectively provided with a fluid channel I207 and a fluid channel II 208 along the length direction, and the temperature of the slot die 201 is controlled by the circulation of a high-low temperature medium in the fluid channel I207 and the fluid channel II 208.
The dissolution unit comprises a dissolution kettle 101 and a stirrer 102, wherein the stirrer is used for uniformly mixing materials in the dissolution kettle 101, and the dissolution kettle 101 is connected with a slit die head 201 through a pipeline 106; the dissolution vessel 101, coagulation bath 202 and conduit 106 are each provided with a heat-insulating jacket.
The size of the gap between the upper die lip 213 and the lower die lip 211 can be adjusted by the movement of the lower die lip 211 in the vertical direction.
The coagulating bath 202 also comprises a counter-pressure roller I203 and a counter-pressure roller II 204 which are in rotary fit and are used for conveying cellulose hydrogel; the coagulation bath 202 is configured to be corrosion resistant.
According to one embodiment of the invention, the film post-treatment unit 7 comprises a drafting unit 3, wherein the drafting unit 3 comprises a drafting roller I302, a drafting roller II303 and a drafting groove 301 with adjustable distance, a counter-pressure roller III 304 and a counter-pressure roller IV 305 with adjustable distance in the vertical direction; the drafting unit 3 is used for modifying the stretching orientation of the cellulose hydrogel.
The drawing tank 301 is configured to resist corrosion, and preferably, the drawing tank 301 includes an acid-resistant and alkali-resistant coating. Drawing the regenerated natural polymer gel, and controlling the rotation speed of a drawing roller II303 to realize different drawing on the longitudinal direction of the hydrogel;
according to one embodiment of the present invention, the film post-treatment unit 7 comprises a cleaning unit 4 comprising a drawing roll iii 402, a drawing roll iv 403, and a cleaning tank 401; the cleaning unit 4 is used for eluting impurities such as alkali, urea, salt and the like remained in the cellulose hydrogel.
The inner side of the cleaning tank 401 is provided to be corrosion resistant, and preferably, the inner side of the cleaning tank 401 contains an acid-resistant and alkali-resistant coating.
According to one embodiment of the invention, the film post-treatment unit comprises a drying unit 5 for cellulose hydrogel drying; the drying unit 5 comprises a five-stage hot air drying box 501 and a multi-roller set 502.
According to one embodiment of the invention, the film post-treatment unit comprises a winding unit 6, the winding unit 6 comprising a counter roll v 601, a counter roll vi 602, a transfer roll I603 and a wind-up roll 604, the winding unit 6 being for winding up regenerated cellulose film.
The method for continuously preparing the regenerated natural polymer film comprises the following steps:
a. placing a natural polymer material into a dissolution kettle 101, adding a solvent, stirring to dissolve the natural polymer material to obtain a natural polymer solution, and carrying out vacuum defoaming; then introducing gas into the dissolution kettle to make the pressure in the kettle be 0-1.6 MPa);
b. the natural polymer solution enters a slot die head 201 and is injected into a coagulating bath 202, and is coagulated in a coagulating agent to obtain regenerated natural polymer gel;
c. the regenerated natural polymer gel is prepared into regenerated natural polymer hydrogel through a drafting unit 3 and a cleaning unit 4;
d. the regenerated natural polymer hydrogel is dried by a drying unit 5 to prepare a regenerated natural polymer membrane; winding is carried out by a winding unit 6;
the temperature difference between the dissolution unit and the solidification unit is controlled to be less than or equal to 30 ℃.
The temperature difference between the dissolution kettle 101 and the slot die 201 and the coagulation bath is controlled to be less than or equal to 30 ℃.
The natural polymer solution can be stably molded by controlling the regeneration of the natural polymer solution and the temperature before the regeneration of the natural polymer solution, so that the regenerated natural polymer film is ensured to be uniform and flat.
According to the present invention, it is preferable to control the temperature difference between the dissolution unit and the solidification unit to 25 ℃ or less, preferably 20 ℃; the temperature difference ensures that the regenerated natural polymer gel is more stable, and the prepared regenerated natural polymer film has more excellent mechanical strength and elongation at break.
According to the present invention, it is preferable that the cellulose solution is extruded from the slot die 201 by increasing the air pressure of the dissolution tank 101.
According to the present invention, preferably, the concentration of the natural polymer solution is 4 to 20wt%; the regenerated natural polymer film prepared from the natural polymer solution with the concentration has more excellent mechanical strength and elongation at break.
According to the invention, the natural polymer material is at least one of cellulose, chitin, chitosan and sodium alginate.
According to the present invention, preferably, the natural polymer material has a molecular polymerization degree of 200 to 1000; in the invention, the natural polymer film prepared from the natural polymer material with the polymerization degree is more stable, and the prepared natural polymer film has more excellent mechanical strength and elongation at break.
According to the invention, the source of cellulose is relatively wide, optionally, the cellulose source is one or more of cotton linter pulp, wood pulp, bamboo pulp, straw pulp, bagasse pulp, reed pulp, sea squirt cellulose, and animal cellulose.
According to the invention, the solvent has a wide selection range and can effectively dissolve natural polymer materials, and the solvent is selected from sodium hydroxide solution, copper ammonia solution and NaOH/CS 2 Solution, base/urea solution or NaOH/thiourea solution.
According to the invention, optionally, the solvent is a base/urea solution; preferably, the solvent is NaOH and urea in water; more preferably, the NaOH and urea aqueous solution is 4-8wt% NaOH, 10-14wt% urea and 78-85wt% water; the solvent is low in cost, high in dissolution speed and high in efficiency, the gelation time of the natural polymer solution is prolonged, and the prepared regenerated natural polymer hydrogel and regenerated natural polymer film have more excellent mechanical strength and elongation at break and excellent optical transmittance.
According to the invention, the coagulating agent has a wider selection range, and optionally, the coagulating agent is one or more of pure water, methanol, ethanol, glycol, DMSO, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, citric acid, phytic acid, nitric acid and benzoic acid; preferably an aqueous solution of 10 to 20% acid; more preferably 10 to 20wt% aqueous citric acid solution. The regenerated natural polymer film prepared by the coagulant has more excellent mechanical strength and elongation at break, and simultaneously ensures high-efficiency production and good film light transmittance.
According to the invention, the thickness of the regenerated natural polymer hydrogel is regulated and controlled through the slot die head 201, and the thickness of the regenerated natural polymer hydrogel is regulated and controlled to be 0.01-3 mm through the lower die lip 211; preferably 0.5 to 1mm; further regulating and controlling the thickness of the regenerated natural polymer film to be 0.01-1 mm; preferably 0.03 to 0.1mm. The regenerated cellulose film in the thickness range has excellent optical transmittance, flexibility and mechanical strength.
According to the invention, the regenerated natural polymer hydrogel is drafted by the draft unit 3, wherein the rotation speed of the draft roller I302 is 5-10 m/min, the rotation speed of the draft roller II303 is 5-15 m/min, and the draft ratio is 1-1.5, so that the mechanical property of the regenerated natural polymer membrane is improved.
According to the present invention, preferably, the drawing unit 3 further contains a coagulant; more preferably, the coagulant is one or more of pure water, methanol, ethanol, ethylene glycol, DMSO, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, citric acid, phytic acid, nitric acid, benzoic acid; the coagulant is added into the drawing unit 3 for drawing, so that the natural polymer film has more excellent mechanical strength and elongation at break and has excellent optical transmittance.
According to the invention, the natural polymer gel after drafting is washed by the washing unit 4 until the solution approaches to the conductivity of pure water, and impurities such as alkali, urea, salt and the like remained in the cellulose hydrogel are eluted, so that the natural polymer gel has excellent optical transmittance.
According to the invention, the washed regenerated natural polymer hydrogel is dried by the drying unit 5 to obtain the regenerated natural polymer membrane, wherein the drying temperature is 40-65 ℃, and the humidity of each section is 7-12%.
According to one embodiment of the invention, the five-stage hot air drying oven 501 is used for carrying out step-by-step heating drying, wherein the initial temperature is 40 ℃, the temperature is further increased by 45 ℃ step by step, the final temperature is 65 ℃, and the humidity of each stage is 7-12%; the gradual drying process from low temperature to high temperature is realized by adopting the drying mode, and the tension and the thermal orientation of the regenerated natural polymer film are regulated by the multi-roller group 502, so that shrinkage wrinkles of the regenerated natural polymer film are avoided.
According to the invention, the dried regenerated natural polymer film is wound by the winding unit 6, and the winding angle is adjusted by moving the transmission roller I603 up and down in the vertical direction, so that the angle between the regenerated natural polymer film and the winding roller 604 is adjusted to be 60-120 degrees; the regenerated natural polymer film is rolled up by adopting the angle, so that the regenerated natural polymer film is prevented from being broken.
The present invention will be described in detail by examples.
Example 1
a. Adding NaOH/thiourea solution (sodium hydroxide: thiourea: water=8:10:82) into a dissolution kettle 101, adding refined bamboo dissolving pulp (DP=1500) into the dissolution kettle 101, a coagulating bath 202 and a pipeline 106 at the temperature of-12 ℃,10 ℃ and 10 ℃ respectively, stirring at a high speed to dissolve cellulose, wherein the concentration of the cellulose is 4wt%, defoaming in vacuum, and introducing air into the dissolution kettle to ensure that the pressure in the kettle is 0.8 MPa;
b. the metering pump 105 is opened, the extrusion speed is controlled to be 5 m/min, the cellulose solution is injected into the coagulant through a slit extrusion die head (the thickness of the gasket is 1.0 mm, the width is 5 cm, the temperature of the slit extrusion die head is 10 ℃) to obtain regenerated cellulose gel, 10wt% citric acid solution is obtained, and the temperature is 10 ℃;
c. the regenerated cellulose gel is drawn by a pair of pressing rollers I203, a pair of pressing rollers II 204 and a transmission roller II212 (the rotation speed of each roller is 5 m/min and the draft ratio is 1:3), and then is drawn by a drawing roller I302 and a drawing roller II303 (the rotation speed of each roller is 5 m/min), and the regenerated cellulose gel enters a cleaning tank 401 after being drawn, is cleaned by a drawing roller III 402 and a drawing roller IV 403 to obtain regenerated cellulose hydrogel, wherein the solvent in a drawing unit 3 is 10wt% sulfuric acid solution, and the solvent in a cleaning unit 4 is pure water;
d. the regenerated cellulose hydrogel enters a drying unit 5 and a winding unit 6 to prepare a regenerated cellulose membrane coiled material; the initial temperature of the five-stage hot air drying box 501 is 30 ℃, the temperature is gradually increased by 5 ℃, the final temperature is 55 ℃, and the humidity of each stage is 10%; the rotational speed of each roller of the multi-roller group 502 and the winding unit is 5 m/min; the regenerated cellulose film is at an angle of 120 ° to the wind-up roll 604.
The finally prepared regenerated cellulose membrane has low transparency, no whitening, thickness of 0.12-mm and width of 36.0-mm, and the whole process takes 185 min.
Example 2
a. Adding NaOH/urea solvent (NaOH: urea: water=7:12:81) into a dissolution kettle 101, adding refined bamboo dissolving pulp (DP=350) into the dissolution kettle 101, and stirring at high speed at-12 ℃, 5 ℃ and 5 ℃ through the temperature of the dissolution kettle 101, a coagulating bath 202 and a pipeline 106 respectively to dissolve cellulose, wherein the concentration of cellulose is 4wt%, defoaming in vacuum, and introducing air into the dissolution kettle to make the pressure in the kettle be 0.8 MPa;
b. the metering pump 105 is opened, the extrusion speed is controlled to be 5 m/min, the cellulose solution is injected into a coagulant through a slit extrusion die head (the thickness of a gasket is 1.0 mm, the width of the gasket is 5 cm, the temperature of the slit extrusion die head is 5 ℃) to obtain regenerated cellulose gel, the coagulant is 10wt% citric acid solution, and the temperature is 5 ℃;
c. the regenerated cellulose gel is drawn by a pair of pressing rollers I203, a pair of pressing rollers II 204 and a transmission roller II212 (the rotation speed of each roller is 5 m/min and the draft ratio is 1:3), and then is drawn by a drawing roller I302 and a drawing roller II303 (the rotation speed of each roller is 5 m/min), and the regenerated cellulose gel enters a cleaning tank 401 after being drawn, is cleaned by a drawing roller III 402 and a drawing roller IV 403 to obtain regenerated cellulose hydrogel, the solvent in a drawing unit 3 is 5wt% sulfuric acid solution, and the solvent in a cleaning unit 4 is pure water;
d. the regenerated cellulose hydrogel enters a drying unit 5 and a winding unit 6 to prepare a regenerated cellulose membrane coiled material; the initial temperature of the five-stage hot air drying box 501 is 40 ℃, the temperature is gradually increased by 5 ℃, the final temperature is 65 ℃, and the humidity of each stage is 10%; the rotational speed of each roller of the multi-roller group 502 and the winding unit is 5 m/min; the regenerated cellulose film is at an angle of 120 ° to the wind-up roll 604.
The finally prepared regenerated cellulose film has high transparency, thickness of 0.12-mm and width of 46-mm, and the whole process takes 185 min.
Example 3
a. Adding NaOH/urea solvent (NaOH: urea: water=7:12:81) into a dissolution kettle 101, adding refined bamboo dissolving pulp (DP=350) into the dissolution kettle 101, and stirring at high speed at-12 ℃, 5 ℃ and 5 ℃ through the temperature of the dissolution kettle 101, a coagulating bath 202 and a pipeline 106 respectively to dissolve cellulose, wherein the concentration of cellulose is 8wt%, defoaming in vacuum, and introducing air into the dissolution kettle to enable the pressure in the kettle to be 0.8 MPa;
b. the metering pump 105 is opened, the extrusion speed is controlled to be 5 m/min, the cellulose solution is injected into a coagulant through a slit extrusion die head (the thickness of a gasket is 1.0 mm, the width is 80 cm, the temperature of the slit extrusion die head is 5 ℃) to obtain cellulose gel, the coagulant is 15wt% citric acid solution, and the temperature is 5 ℃;
c. the cellulose gel is drawn by a counter-pressure roller I203, a counter-pressure roller II 204 and a transmission roller II212 (the rotation speed of each roller is 5 m/min and the draft ratio is 1:3), and then is drawn by a drawing roller I302 and a drawing roller II303 (the rotation speed of each roller is 5 m/min), and is fed into a cleaning tank 401 and is cleaned by a drawing roller III 402 and a drawing roller IV 403 to obtain cellulose hydrogel, the solvent in a drawing unit 3 is 5wt% sulfuric acid solution, and the solvent in a cleaning unit 4 is pure water;
d. the cellulose hydrogel enters a drying unit 5 and a winding unit 6 to prepare a cellulose membrane coiled material; the initial temperature of the five-stage hot air drying box 501 is 40 ℃, the temperature is gradually increased by 5 ℃, the final temperature is 65 ℃, and the humidity of each stage is 10%; the rotational speed of each roller of the multi-roller group 502 and the winding unit is 5 m/min; the regenerated cellulose film is at an angle of 120 ° to the wind-up roll 604.
The finally prepared cellulose film has high transparency, thickness of 0.12mm and width of 780 and mm, and the whole process takes 60 minutes.
Example 4
The difference from example 2 is that in step b, the coagulant is a 20wt% citric acid solution and the rest of the operating conditions are the same as in example 2.
The finally prepared regenerated cellulose film has high transparency, thickness of 0.13-mm and width of 48-mm, and the whole process takes 185 min.
Example 5
The difference from example 2 is that the temperatures of dissolution vessel 101, coagulation bath 202 and line 106 in step a are-12 ℃, 12 ℃ and 12 ℃ respectively, and the other conditions are the same as in example 2.
The finally prepared regenerated cellulose membrane has high transparency, thickness of 0.12-mm and width of 42-mm, and the whole process takes 180 min.
Example 6
a. Adding NaOH/urea solvent (NaOH: urea: water=11:4:85) into a dissolution kettle, adding chitin (DP=550), stirring at high speed, adjusting the temperature of the reaction kettle to-30 ℃, maintaining for 3h, and stirring while thawing until the temperature is 5 ℃; repeating the freezing-thawing process for 2 times to dissolve chitin, wherein the concentration of chitin is 2wt%, vacuum defoamating, and introducing air into the dissolution kettle to make the pressure in the kettle be 0.8 MPa, and the temperatures of the coagulation bath 202 and the pipeline 106 are respectively 0 ℃ and 0 ℃; the other conditions were the same as in example 1.
The finally prepared regenerated cellulose film has high transparency, thickness of 0.11-mm and width of 40-mm, and the whole process takes 220min.
Example 7
The natural polymer material added in the step a is cellulose (DP=1000); the other conditions were the same as in example 2.
The final cellulose film has high transparency, thickness of 0.12-mm and width of 46.0-mm, and the whole process takes 185 min.
Example 8
Unlike example 2, the dissolution vessel 101 was fed with CO 2 Gas, coagulation bath 202 is at CO 2 In a gas atmosphere; the other implementation conditions were the same as in example 2;
the finally prepared regenerated cellulose membrane has high transparency, thickness of 0.12-mm and width of 48-mm, and the whole process takes 200 min.
Example 9
Different from example 2, the rotation speed of the drawing roller II303 is controlled to be 10 m/min, different drawing is realized on the longitudinal direction of the hydrogel, and the drawing ratio is controlled to be 1:2; the finally prepared regenerated cellulose film has high transparency, thickness of 0.06 mm and width of 40 mm, and the whole process takes 165 min.
Example 10
Unlike example 2, the rotation speed of the drawing roller II303 was controlled to be 25 m/min, different drawing was realized for the longitudinal direction of the hydrogel, and the drawing ratio was controlled to be 1:5; the finally prepared regenerated cellulose membrane has high transparency, thickness of 0.03-mm and width of 40-mm, and the whole process takes 130 min.
Comparative example 1
Casting method 1:
preparing NaOH/urea solvent (NaOH: urea: water=7:12:81), adding refined bamboo dissolving pulp (DP=350), pre-cooling to-12 ℃, and stirring at high speed to dissolve cellulose, wherein the concentration of cellulose is 6wt%. And then centrifugally defoaming, pouring the upper layer solution into a clean mould with the thickness of 1mm, then smoothly placing the mould into 5wt% citric acid aqueous solution for coagulating bath, standing for 12h, washing by using deionized water until the aqueous solution is close to the conductivity of pure water, and airing in the air for 24 hours at room temperature to obtain the cellulose film. The finally prepared film has the advantages of whitening color, low transparency and poor mechanical property.
Comparative example 2
Casting method 2:
preparing NaOH/urea solvent (NaOH: urea: water=7:12:81), adding refined bamboo dissolving pulp (DP=350), pre-cooling to-12 ℃, and stirring at high speed to dissolve cellulose, wherein the concentration of cellulose is 6wt%. And then centrifugally defoaming, pouring the upper layer solution into a clean mould with the thickness of 1mm, then stably putting a 15wt% citric acid aqueous solution as a coagulating bath, standing for 5min, washing by using deionized water until the aqueous solution is close to the conductivity of pure water, and airing in the air for 24 hours at room temperature to obtain the cellulose film. The final shrinkage of the regenerated cellulose membrane is serious and the mechanical property of the regenerated cellulose membrane is poor, and the whole process takes about 28 hours.
Comparative example 3
a. Adding NaOH/urea solvent (NaOH: urea: water=7:12:81) into a dissolution kettle, adding refined bamboo dissolving pulp (DP=350) into the dissolution kettle 101, the coagulation bath 202 and the pipeline 106 at the temperature of-12 ℃, 30 ℃ and 30 ℃ respectively, stirring at high speed to dissolve cellulose, wherein the concentration of cellulose is 4wt%, defoaming in vacuum, and introducing air into the dissolution kettle to ensure that the pressure in the kettle is 0.8 MPa;
b. the metering pump 105 is opened, the extrusion speed is controlled to be 5 m/min, the cellulose solution is injected into a coagulant through a slit extrusion die head (the thickness of a gasket is 1.0 mm, the width of the gasket is 5 cm, the temperature of the slit extrusion die head is 25 ℃) to obtain regenerated cellulose gel, the coagulant is 15wt% citric acid solution, and the temperature is 25 ℃; the rest of the procedure is as in example 1
The thickness of the regenerated cellulose hydrogel is 0.1mm, the width is 50 mm, the whole process takes 125 minutes, and the prepared film has low transparency, serious whitening and poor mechanical property.
Comparative example 4
Unlike example 2, the coagulant was a 5wt% citric acid solution, and the final cellulose solution failed to gel, failing to achieve continuous production.
Comparative example 5
In step c, the rotation speed of the transfer roller II212 was adjusted to control the draft ratio to 1:5.5, and the other operating conditions were the same as in example 2, except for example 2.
The hydrogel in the coagulation bath breaks, and continuous preparation cannot be realized.
Compared with comparative examples 1 and 2, the preparation method of the invention can realize rapid and continuous preparation of the regenerated natural polymer film; compared with comparative examples 1 and 2 and 3, the regenerated natural polymer film prepared by the technical scheme of the invention has high transparency and good mechanical property. In contrast to comparative example 4 and comparative example 5, the polymer films produced by the method of the present invention were continuous and did not break during processing.
According to FIG. 4, the regenerated natural polymer film prepared by the method of the invention has more excellent mechanical strength.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including the combination of the individual specific technical features in any suitable way. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition. Such simple variations and combinations are likewise to be regarded as being within the scope of the present disclosure.
Claims (25)
1. A method for continuously preparing a regenerated natural polymer film, comprising:
(1) Mixing and dissolving a natural polymer material and a solvent to obtain a natural polymer solution, and carrying out vacuum defoaming;
(2) The natural polymer solution is solidified in a coagulant to obtain regenerated natural polymer gel;
(3) Drawing and cleaning the regenerated natural polymer gel to prepare regenerated natural polymer hydrogel;
(4) Drying the regenerated natural polymer hydrogel to prepare a regenerated natural polymer membrane; winding is carried out through winding;
controlling the operation temperature difference between dissolution and solidification to be less than or equal to 30 ℃; controlling the draft ratio of the regenerated natural polymer gel in the draft process to be 1:1-1:5;
the solvent is sodium hydroxide solution, copper ammonia solution, naOH/CS 2 One or more of a solution, a base/urea solution, and a NaOH/thiourea solution;
the coagulant is 10-20% acid aqueous solution;
the concentration of the natural polymer material in the natural polymer solution is 4-20wt%;
the polymerization degree of the natural polymer material is 200-1000.
2. The method of claim 1, wherein the natural polymeric material is at least one of cellulose, chitin, chitosan, and sodium alginate.
3. The method of claim 2, wherein the cellulose source is one or more of cotton linter pulp, wood pulp, bamboo pulp, straw pulp, bagasse pulp, reed pulp, sea squirt cellulose, and animal cellulose.
4. A method according to any one of claims 1 to 3, wherein the temperature difference between dissolution and solidification is controlled to 25 ℃ or less.
5. The method according to claim 4, wherein the temperature difference between dissolution and solidification is controlled to 20 ℃ or less.
6. The method of claim 5, wherein the temperature difference between dissolution and solidification is controlled to be 0-20 ℃.
7. The method according to claim 1, wherein the dissolution and solidification of the natural polymer solution are performed in an inert gas atmosphere.
8. The method of claim 7, wherein the inert gas atmosphere is CO 2 、N 2 A rare gas atmosphere.
9. The method of claim 1, wherein the solvent is a base/urea solution.
10. The method of claim 9, wherein the base/urea solution is an aqueous NaOH and urea solution.
11. The method of claim 10, wherein the NaOH and urea aqueous composition comprises: 4-8wt% of NaOH, 10-14wt% of urea and 78-85wt% of water.
12. The method according to claim 1, wherein the coagulant is 10 to 20wt% aqueous citric acid.
13. The method of claim 1, wherein the drawing is performed in the presence of a coagulant.
14. The method of claim 1, wherein the coagulant contains one or more of pure water, methanol, ethanol, ethylene glycol, DMSO, hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, citric acid, phytic acid, nitric acid, and benzoic acid.
15. The method of claim 1, wherein,
the drying temperature of the regenerated natural polymer hydrogel is 40-65 ℃.
16. The method of claim 1, wherein the regenerating natural polymer hydrogel is dried using a stepped temperature ramp.
17. The method of claim 1, wherein the regenerated natural polymer hydrogel has a thickness of 0.01 to 3mm.
18. The method of claim 17, wherein the regenerated natural polymer hydrogel has a thickness of 1-2 mm.
19. A method according to any one of claims 1 to 3, wherein the regenerated natural polymer film has a thickness of 0.01 to 1mm.
20. The method of claim 19, wherein the regenerated natural polymer film has a thickness of 0.03 to 0.1mm.
21. A method according to any one of claim 1 to 3, wherein,
the method is carried out in a device comprising a dissolving unit (1), a solidifying unit (2), a film post-treatment unit;
the dissolving unit (1) is used for preparing natural polymer solution for preparing the film;
the solidification unit (2) comprises a slot die head (201) and a solidification bath (202), wherein natural polymer solution is extruded from the slot die head (201) and enters the solidification bath (202) to be solidified to prepare regenerated natural polymer gel;
the film post-treatment unit is used for cleaning, modifying, drying and rolling the regenerated natural polymer gel to prepare the regenerated natural polymer film and comprises a drafting unit (3), a cleaning unit (4), a drying unit (5) and a winding unit (6).
22. The method according to claim 21, characterized in that the method comprises:
a. placing the natural polymer material into a dissolution kettle (101), adding a solvent, stirring to dissolve the natural polymer material, and obtaining a natural polymer solution, and carrying out vacuum defoaming;
b. the natural polymer solution enters a slot die head and is injected into a coagulating bath (202), and is coagulated in a coagulant to obtain regenerated natural polymer gel;
c. the regenerated natural polymer gel is prepared into regenerated natural polymer hydrogel through a drafting unit (3) and a cleaning unit (4);
d. the regenerated natural polymer hydrogel is dried by a drying unit (5) to prepare a regenerated natural polymer membrane; winding is carried out through a winding unit (6);
the temperature difference between the dissolution unit and the solidification unit is controlled to be less than or equal to 30 ℃.
23. A regenerated natural polymer film obtained by the method of any one of claims 1 to 22.
24. The regenerated natural polymer film according to claim 23 having a thickness of 0.01 to 1mm.
25. The regenerated natural polymer film according to claim 24 having a thickness of 0.03 to 0.1mm.
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| 田道全等.近代材料科学研究技术进展.武汉理工大学出版社,2012,(第1版),319-320. * |
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