CN115637605A - Lyocell dissolving pulp and preparation method thereof - Google Patents
Lyocell dissolving pulp and preparation method thereof Download PDFInfo
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- CN115637605A CN115637605A CN202211307657.3A CN202211307657A CN115637605A CN 115637605 A CN115637605 A CN 115637605A CN 202211307657 A CN202211307657 A CN 202211307657A CN 115637605 A CN115637605 A CN 115637605A
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- 229920000875 Dissolving pulp Polymers 0.000 title claims abstract description 71
- 229920000433 Lyocell Polymers 0.000 title claims abstract description 69
- 238000002360 preparation method Methods 0.000 title abstract description 17
- 238000004061 bleaching Methods 0.000 claims abstract description 89
- 239000002002 slurry Substances 0.000 claims abstract description 87
- 239000002023 wood Substances 0.000 claims abstract description 72
- 239000000835 fiber Substances 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims abstract description 50
- 230000004048 modification Effects 0.000 claims abstract description 48
- 238000012986 modification Methods 0.000 claims abstract description 48
- 238000010411 cooking Methods 0.000 claims abstract description 33
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 72
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 34
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 34
- 239000001301 oxygen Substances 0.000 claims description 34
- 229910052760 oxygen Inorganic materials 0.000 claims description 34
- 238000010306 acid treatment Methods 0.000 claims description 32
- 230000008569 process Effects 0.000 claims description 25
- 239000003513 alkali Substances 0.000 claims description 23
- 238000009897 hydrogen peroxide bleaching Methods 0.000 claims description 21
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 15
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 230000007062 hydrolysis Effects 0.000 claims description 10
- 238000006460 hydrolysis reaction Methods 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 102100030386 Granzyme A Human genes 0.000 claims description 8
- 101001009599 Homo sapiens Granzyme A Proteins 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 7
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 6
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 6
- 238000005470 impregnation Methods 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 3
- 230000003301 hydrolyzing effect Effects 0.000 claims 2
- 239000013055 pulp slurry Substances 0.000 claims 2
- 238000005987 sulfurization reaction Methods 0.000 claims 1
- 239000011347 resin Substances 0.000 abstract description 12
- 229920005989 resin Polymers 0.000 abstract description 12
- 229910021645 metal ion Inorganic materials 0.000 abstract description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 8
- 230000009257 reactivity Effects 0.000 abstract description 5
- 229920002678 cellulose Polymers 0.000 description 12
- 239000001913 cellulose Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 10
- 238000005406 washing Methods 0.000 description 9
- 239000002351 wastewater Substances 0.000 description 9
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 238000004073 vulcanization Methods 0.000 description 5
- 244000166124 Eucalyptus globulus Species 0.000 description 4
- LFTLOKWAGJYHHR-UHFFFAOYSA-N N-methylmorpholine N-oxide Chemical compound CN1(=O)CCOCC1 LFTLOKWAGJYHHR-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229920000297 Rayon Polymers 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000011121 hardwood Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000011122 softwood Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 238000005904 alkaline hydrolysis reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- -1 carboxyethyl group Chemical group 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000004076 pulp bleaching Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 229910001948 sodium oxide Inorganic materials 0.000 description 1
- 238000005486 sulfidation Methods 0.000 description 1
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- 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
- Y02W30/64—Paper recycling
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Abstract
The invention discloses a Lyocell dissolving pulp and a preparation method thereof, wherein the preparation method of the Lyocell dissolving pulp comprises the following steps: obtaining wood chips to be treated, and carrying out prehydrolysis on the wood chips to be treated; cooking the pre-hydrolyzed wood chips to be treated to obtain initial slurry; bleaching the initial pulp to obtain lyocell dissolving pulp; wherein the initial pulp is subjected to a fiber modification treatment during the bleaching treatment. The method can improve the indexes of the lyocell dissolving pulp such as alpha cellulose proportion, reactivity, whiteness, metal ion content, resin content and the like to a certain extent.
Description
Technical Field
The invention relates to the technical field of dissolving pulp preparation, in particular to lyocell dissolving pulp and a preparation method thereof.
Background
The lyocell fiber is the second-generation green renewable cellulose fiber after the viscose fiber, the production process has no chemical reaction, the used solvent is nontoxic, the solvent recovery rate is high, and the lyocell fiber is energy-saving, environment-friendly and sustainable in development.
As a raw material for producing the lyocell fibers, the lyocell has high requirements on the quality of dissolving pulp, and compared with viscose pulp, the lyocell pulp has higher requirements on the indexes such as alpha cellulose proportion, reaction performance, whiteness, metal ion content, resin content and the like.
At present, the preparation of the conventional dissolving pulp is difficult to meet the quality requirement of the lyocell fiber.
Disclosure of Invention
The invention provides a lyocell dissolving pulp and a preparation method thereof, which aim to solve the problem that the preparation of the dissolving pulp is difficult to meet the quality requirement of lyocell fibers.
In order to solve the technical problems, the invention provides a preparation method of lyocell dissolving pulp, which comprises the following steps: obtaining wood chips to be treated, and carrying out prehydrolysis on the wood chips to be treated; cooking the pre-hydrolyzed wood chips to be treated to obtain initial slurry; bleaching the initial pulp to obtain lyocell dissolving pulp; wherein the initial pulp is subjected to a fiber modification treatment during the bleaching treatment.
Wherein, the initial pulp is bleached to obtain lyocell dissolving pulp; wherein the step of subjecting the initial slurry to a fiber modification treatment during the bleaching treatment comprises: carrying out first bleaching treatment on the initial slurry; carrying out fiber modification treatment on the initial slurry after the first bleaching treatment; and carrying out second bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp.
Wherein the step of subjecting the initial slurry after the first bleaching treatment to a fiber modification treatment comprises: and (3) carrying out fiber modification treatment on the initial slurry after the first bleaching treatment by using sodium hydroxide and acrylamide.
Wherein the step of performing fiber modification treatment on the initial slurry after the first bleaching treatment by using sodium hydroxide and acrylamide comprises the following steps: within a preset temperature, carrying out fiber modification treatment for a preset time length on initial slurry after first bleaching treatment at a preset concentration through sodium hydroxide and acrylamide; wherein the range of the preset temperature is 70-90 ℃, the range of the preset concentration is 5-10%, and the range of the preset duration is 30-120 minutes; the alkali consumption range of the sodium hydroxide is 1.0-2.0%, and the acrylamide consumption range is 0.05-0.20%.
Wherein the step of subjecting the initial slurry to a first bleaching treatment comprises: carrying out oxygen delignification treatment on the initial slurry; carrying out acid treatment on the initial slurry after oxygen delignification treatment by using sulfuric acid; carrying out ozone bleaching treatment on the initial slurry after the acid treatment; the step of subjecting the fiber-modified initial pulp to a second bleaching treatment to obtain a dissolving pulp comprises: and carrying out at least one section of pressure hydrogen peroxide bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp.
Wherein the dosage range of ozone for the ozone bleaching treatment is 0.2-1.5%, and the temperature range is 30-70 ℃; the oxygen pressure range of the pressure hydrogen peroxide bleaching treatment is 0.20-0.30MPa, the concentration range of initial slurry during the pressure hydrogen peroxide bleaching treatment is 10-20%, the temperature range is 105-120 ℃, and the bleaching time range is 60-90 minutes; the concentration range of initial slurry during oxygen delignification treatment is 10-20%, the alkali dosage range is 1.5-4.5%, the oxygen pressure range is 0.8-1.0MPa, the temperature range is 95-110 ℃, and the heat preservation time range is 60-80 minutes; the initial slurry concentration during acid treatment ranges from 10 to 20%, the pH ranges from 1.5 to 3.5, the temperature ranges from 70 to 80 ℃, and the time ranges from 60 to 80 minutes.
The method comprises the following steps of obtaining wood chips to be treated, and performing prehydrolysis on the wood chips to be treated, wherein the steps comprise: obtaining wood chips to be treated, and performing presteaming hydrolysis on the wood chips to be treated; wherein the temperature range of the pre-gas steam hydrolysis is 130-170 ℃, and the time range is 20-80 minutes.
The method comprises the following steps of obtaining wood chips to be treated, and performing prehydrolysis on the wood chips to be treated, wherein the steps comprise: obtaining wood chips to be treated, and carrying out water impregnation prehydrolysis on the wood chips to be treated, wherein the temperature range of the water impregnation prehydrolysis mode is 130-170 ℃, and the time range is 20-80 minutes.
Wherein, the step of cooking the wood chips to be treated after the prehydrolysis to obtain the initial slurry comprises the following steps: carrying out sulfate cooking on the wood chips to be treated after the prehydrolysis through sodium hydroxide and sodium sulfide to obtain initial slurry; wherein, the liquid ratio range of the sulfate cooking is 3-5.
In order to solve the above technical problems, the present invention also provides a lyocell dissolving pulp prepared by the method of any one of the above processes.
The invention has the beneficial effects that: different from the situation of the prior art, the wood chips to be treated are obtained, the wood chips to be treated are subjected to prehydrolysis, the wood chips to be treated after the prehydrolysis are cooked to obtain initial pulp, and the initial pulp is subjected to bleaching treatment to obtain lyocell dissolving pulp; the method comprises the following steps of carrying out fiber modification treatment on initial pulp in the bleaching treatment process, reducing hydrogen bond bonding among cellulose molecular chains, destroying a rigid structure of a crystallization area, improving the dissolving capacity of the fiber, and simultaneously, the modified fiber has better bleachability in the later-stage bleaching process of dissolving pulp, has better bleaching effect and higher whiteness and purity of pulp, so that the lyocell dissolving pulp is improved to a certain extent in indexes such as alpha cellulose proportion, reactivity, whiteness, metal ion content, resin content and the like, and the quality requirement of the lyocell fiber is met.
Drawings
FIG. 1 is a schematic flow chart showing an example of a method for producing a lyocell dissolving pulp of the present invention;
FIG. 2 is a schematic flow chart of another embodiment of the method for producing a lyocell dissolving pulp of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic flow chart of an embodiment of the method for preparing lyocell dissolving pulp according to the present invention.
Step S11: obtaining wood chips to be treated, and performing prehydrolysis on the wood chips to be treated.
Obtaining the wood chips to be treated for preparing the lyocell dissolving pulp. The wood chips to be treated in this embodiment may include any one of softwood, hardwood, and a mixture thereof, which is not limited herein.
After the wood chips to be treated are obtained, the wood chips to be treated can be cleaned so as to remove impurities, dust and other substances on the wood chips to be treated. In a specific application scenario, the wood chips to be treated can be washed with clean water. In another specific application scenario, the wood chips to be treated can be washed by washing wastewater, wherein the washing wastewater can comprise circularly washed clean water or wastewater obtained after the lyocell dissolving pulp is washed, so that the washing wastewater can be recycled, and the production cost of the dissolving pulp is saved.
The wood chips to be treated are prehydrolyzed, so that air in the wood chips to be treated can be discharged, the temperature is increased and stabilized, the wood chips to be treated can quickly absorb liquid medicine after entering a subsequent cooking procedure, the temperature of the wood chips to be treated is higher, the temperature rise time of the wood chips to be treated in the subsequent cooking procedure can be saved, and the preparation efficiency of the lyocell dissolving pulp is improved.
Step S12: and (4) cooking the wood chips to be treated after prehydrolysis to obtain initial slurry.
And (4) cooking the wood chips to be treated after prehydrolysis to obtain initial slurry.
In a specific application scenario, the wood chips to be treated can be cooked by using sodium hydroxide and sodium sulfide and controlling the temperature, and the key point of the cooking section is controlled by an H factor, so that initial slurry is obtained. Wherein the H factor defines: the relative reaction rate constant at each cooking temperature is a constant integral over the cooking time.
Step S13: bleaching the initial pulp to obtain lyocell dissolving pulp; wherein the initial pulp is subjected to a fibre modification treatment during the bleaching treatment.
And (3) carrying out bleaching treatment on the initial pulp, wherein the fiber modification treatment is carried out on the initial pulp in the bleaching treatment process, and finally the lyocell dissolving pulp is obtained.
The production principle of the lyocell fiber is that the strong interaction of NMMO (N-methylmorpholine-N-oxide) and cellulose destroys the hydrogen bond action among cellulose molecules, so that the dissolution occurs.
From the above principle, it can be seen that the hydrogen bonding of the fibers and the highly rigid structure of the crystalline regions have a great influence on the solubility. The embodiment is through carrying out fibre modification treatment to cellulose in the bleaching process of initial thick liquid, can reduce the hydrogen bond between the cellulose molecular chain, destroy the rigid structure in crystallization zone, thereby make inside NMMO solution can permeate the fibre more fast when preparing lyocell fibre, improve fibrous dissolving capacity, fibre after modification treatment has better bleachability in dissolving thick liquid back end bleaching process simultaneously, bleaching effect is better, the whiteness degree and the purity of thick liquids are all higher, make lyocell dissolve thick liquid obtain certain improvement in indexes such as first cellulose proportion, the reactivity, whiteness degree, metal ion content, resin content.
Through the steps, the preparation method of the lyocell dissolving pulp obtains the wood chips to be treated, prehydrolyzes the wood chips to be treated, digests the prehydrolyzed wood chips to be treated to obtain initial pulp, and bleaches the initial pulp to obtain the lyocell dissolving pulp; the method comprises the following steps of carrying out fiber modification treatment on initial pulp in the bleaching treatment process, reducing hydrogen bond bonding among cellulose molecular chains, destroying a rigid structure of a crystallization area, improving the dissolving capacity of the fiber, and simultaneously, the modified fiber has better bleachability in the later-stage bleaching process of dissolving pulp, has better bleaching effect and higher whiteness and purity of pulp, so that the lyocell dissolving pulp is improved to a certain extent in indexes such as alpha cellulose proportion, reactivity, whiteness, metal ion content, resin content and the like, and the quality requirement of the lyocell fiber is met.
Referring to fig. 2, fig. 2 is a schematic flow chart of another embodiment of the preparation method of lyocell dissolving pulp of the present invention.
Step S21: obtaining wood chips to be treated, and carrying out prehydrolysis on the wood chips to be treated.
Obtaining the wood chips to be treated for preparing the lyocell dissolving pulp. The wood chips to be treated in this embodiment may include any one of softwood, hardwood, and a mixture thereof, which is not limited herein.
In a specific application scenario, the wood chips to be treated may be subjected to presteaming hydrolysis. The steam prehydrolysis refers to a step of pretreating with water, steam or dilute acid in a closed container at a certain temperature and pressure.
Wherein the temperature range of the pre-gas steam hydrolysis is 130-170 ℃, and specifically can be 130 ℃, 140 ℃, 151 ℃, 160 ℃, 168 ℃ or 170 ℃ and the like. The time range is 20 to 80 minutes, and specifically, 20 minutes, 25 minutes, 31 minutes, 35 minutes, 38 minutes, 42 minutes, 49 minutes, 52 minutes, 55 minutes, 60 minutes, 67 minutes, 71 minutes, 75 minutes, 80 minutes, or the like can be given.
In another specific application scenario, the wood chips to be treated can be subjected to water soaking prehydrolysis, wherein the temperature range of the water soaking prehydrolysis mode is 130-170 ℃, specifically 130 ℃, 142 ℃, 150 ℃, 165 ℃, 166 ℃ or 170 ℃ and the like, and the time range is 20-80 minutes. Specifically, the time may be 20 minutes, 24 minutes, 30 minutes, 35 minutes, 38 minutes, 42 minutes, 49 minutes, 53 minutes, 55 minutes, 60 minutes, 67 minutes, 70 minutes, 75 minutes, or 80 minutes.
Step S22: and (3) carrying out sulfate cooking on the wood chips to be treated after prehydrolysis through sodium hydroxide and sodium sulfide to obtain initial slurry.
The method comprises the following steps of adopting a sulfate cooking method, specifically, carrying out sulfate cooking on wood chips to be treated after prehydrolysis through sodium hydroxide and sodium sulfide to obtain initial slurry.
Wherein, the liquor ratio range of sulfate cooking is 3; the amount of sodium hydroxide is in the range of 17-21%, and specifically may be 17%, 18%, 19%, 20%, 21%, or the like. The vulcanization degree may be in the range of 20 to 30%, specifically 20%, 22%, 25%, 26%, 27%, 29%, 30%, or the like. The cooking H factor is controlled within the range of 550-1300, and specifically can be 550, 600, 620, 630, 650, 680, 700, 750, 790, 800, 820, 860, 930, 950, 1000, 1150, 1260 or 1300. The degree of sulfidation is the percentage of sodium sulfide to active base (sodium hydroxide in this invention) in terms of sodium oxide.
Step S23: carrying out first bleaching treatment on the initial slurry; carrying out fiber modification treatment on the initial slurry after the first bleaching treatment; and carrying out second bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp.
Carrying out oxygen delignification treatment on the initial slurry; carrying out acid treatment on the initial slurry after oxygen delignification treatment by using sulfuric acid; carrying out first bleaching treatment on the initial slurry after the acid treatment; carrying out fiber modification treatment on the initial slurry after the first bleaching treatment; and carrying out second bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp. Wherein the first bleaching treatment comprises an ozone treatment and the second bleaching treatment comprises a pressurized hydrogen peroxide bleaching treatment.
Specifically, when the initial slurry is subjected to oxygen delignification treatment, the concentration of the initial slurry in the oxygen delignification treatment may be in the range of 10 to 20%, specifically 10%, 12%, 15%, 18%, 20%, or the like; the amount of the base is 1.5-4.5%, specifically 1.5%, 1.8%, 2.0%, 2.4%, 2.8%, 3.1%, 3.4%, 3.9%, 4.0%, 4.2%, or 4.5%; the oxygen pressure range is 0.8-1.0MPa, specifically 0.8MPa, 0.9MPa or 1.0 MPa; the temperature range is 95-110 deg.C, specifically 95 deg.C, 96 deg.C, 98 deg.C, 100 deg.C, 102 deg.C, 105 deg.C, 108 deg.C or 110 deg.C; the holding time is 60-80 minutes, specifically 60 minutes, 65 minutes, 69 minutes, 70 minutes, 72 minutes, 75 minutes, 78 minutes or 80 minutes, and the like, wherein the alkali amount is a general term in the industry and represents the ratio of the alkali (sodium hydroxide in the invention) mass to the oven dry mass of the steamed sample, and the alkali amount is represented by mass percentage. The same applies to the dosage.
After the oxygen delignification treatment, performing acid treatment on the initial slurry after the oxygen delignification treatment by using sulfuric acid, wherein the concentration of the initial slurry during the acid treatment is specifically 10-20%, and specifically 10%, 13%, 15%, 17%, 20% or the like; the pH range is 1.5-3.5, specifically 1.5, 1.9, 2.1, 2.3, 2.6, 3.0, 3.4 or 3.5; the temperature range is 70-80 deg.C, specifically 70 deg.C, 72 deg.C, 75 deg.C, 76 deg.C, 78 deg.C or 80 deg.C etc.; the time range is 60 to 80 minutes, and specifically, 60 minutes, 65 minutes, 69 minutes, 70 minutes, 72 minutes, 75 minutes, 78 minutes, 80 minutes, or the like can be used.
After the acid treatment, the initial slurry after the acid treatment is subjected to ozone bleaching treatment, specifically, the amount of ozone used in the ozone bleaching treatment is in the range of 0.2 to 1.5%, specifically, 0.2%, 0.5%, 0.8%, 1.0%, 1.1%, 1.3%, or 1.5%, and the like, and the temperature range is 30 to 70 ℃, specifically, 30 ℃, 35 ℃, 40 ℃, 42 ℃, 48 ℃, 56 ℃, 61 ℃, 65 ℃, or 70 ℃. In this example, the resin content in the initial slurry can be greatly reduced by subjecting the initial slurry to ozone oxidation. And the ozone oxidation does not influence the gray scale and the metal ion content of the initial slurry, so that the resin content in the slurry can be reduced, and the whiteness of the slurry can be improved. In addition, in the embodiment, the ozone is used for bleaching, so that the bleaching by adopting chlorine-containing substances is avoided, the chlorine-containing bleaching has the defects that the water consumption for bleaching is large, the wastewater is difficult to treat, and carcinogenic substances such as dioxin exist, and the like, and the ozone bleaching replaces the chlorine-containing bleaching, so that the water consumption for bleaching can be further reduced, and the environmental protection property and the safety of the preparation of the dissolving pulp are improved.
In a specific application scenario, after ozone bleaching, the initial slurry after ozone bleaching can be washed to obtain initial slurry and washing wastewater. The washing wastewater obtained in the step S11 can be used for washing the wood chips to be treated in the step S11, so that the wood chips to be treated can be washed by using the temperature of the washing wastewater and the residual hydrogen peroxide, the utilization rate of the hydrogen peroxide is increased and the washing cleanliness of the wood chips to be treated is increased under the condition that the washing wastewater and the hydrogen peroxide are recycled, and the hydrogen peroxide can also remove the resin in the wood chips to be treated to a certain degree, thereby further reducing the resin content in the dissolving pulp.
After the ozone treatment, the initial slurry after the first bleaching treatment is subjected to a fiber modification treatment.
In a specific application scenario, the step of performing fiber modification treatment includes: and (3) carrying out fiber modification treatment on the initial slurry after the first bleaching treatment by using sodium hydroxide and acrylamide. And carrying out fiber modification treatment on the initial slurry after the first bleaching treatment at a preset concentration for a preset time length by using sodium hydroxide and acrylamide at a preset temperature.
Specifically, the preset temperature range of the fiber modification treatment is 70-90 ℃, and specifically may be 70 ℃, 72 ℃, 75 ℃, 76 ℃, 79 ℃, 80 ℃, 82 ℃, 85 ℃, 86 ℃, 88 ℃, or 90 ℃ and the like; the preset concentration range of the initial slurry is 5-10%, and specifically can be 5%, 6%, 7%, 8%, 9%, 10% or the like; the preset time period ranges from 30 minutes to 120 minutes, and specifically can be 30 minutes, 35 minutes, 40 minutes, 42 minutes, 48 minutes, 50 minutes, 55 minutes, 62 minutes, 75 minutes, 86 minutes, 95 minutes, 101 minutes, 114 minutes, 120 minutes, or the like; the alkali consumption range of sodium hydroxide is 1.0-2.0%, specifically 1.0, 1.3, 1.5, 1.7 or 2; the amount of acrylamide to be used may be in the range of 0.05 to 0.20%, specifically 0.05%, 0.08%, 0.10%, 0.13%, 0.15%, 0.19%, 0.20%, etc.
And after the fiber modification treatment, carrying out secondary bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp.
Wherein the step of the second bleaching treatment comprises: and carrying out at least one section of pressure hydrogen peroxide bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp. Specifically, the one-stage pressure hydrogen peroxide bleaching treatment or the two-stage pressure hydrogen peroxide bleaching treatment may be performed.
The oxygen pressure range of the pressure hydrogen peroxide bleaching treatment is 0.20-0.30MPa, specifically 0.20MPa, 0.22MPa, 0.25MPa, 0.26MPa, 0.28MPa or 0.30 MPa; the concentration of the initial slurry in the pressure hydrogen peroxide bleaching treatment is 10-20%, specifically 10%, 12%, 13%, 15%, 16%, 18%, 20% or the like; the temperature range is 105-120 deg.C, and specifically 105 deg.C, 108 deg.C, 110 deg.C, 111 deg.C, 112 deg.C, 115 deg.C, 116 deg.C or 120 deg.C; the bleaching time is in the range of 60 to 90 minutes, and specifically, 60 minutes, 65 minutes, 71 minutes, 75 minutes, 79 minutes, 80 minutes, 82 minutes, 86 minutes, or 90 minutes, or the like may be mentioned.
In the bleaching process, specifically in the alkali treatment process between the ozone bleaching and the hydrogen peroxide bleaching process, a carboxyethyl group is introduced into the cellulose, and the cellulose and acrylamide are subjected to conjugate addition reaction under alkaline conditions, and alkaline hydrolysis is performed to generate modified cellulose. The advantages of modifying the fibers in the alkaline treatment process are: 1. the alkaline condition of the alkali treatment process is utilized to create an alkaline environment for fiber modification, and 2, the fiber modification process and the alkali treatment process are combined into a whole, so that the processes are reduced, and the production cost is reduced. The dissolving pulp prepared from the modified fiber is superior to unmodified pulp in the indexes of alpha cellulose proportion, reaction performance, whiteness, metal ion content, resin content and the like.
The preparation method and performance of the lyocell dissolving pulp of the above formulation according to the present invention will be examined below with reference to a plurality of specific examples.
Example 1:
the wood chips are prehydrolyzed. Taking 100g of eucalyptus pieces, and carrying out prehydrolysis by adopting prehydrolysis steam hydrolysis at 150 ℃ for 60min.
The wood chips are cooked. A sulfate cooking method is adopted, the liquor ratio is 4, the using amount of NaOH is 20%, the vulcanization degree is 25%, and the cooking H factor is controlled to be 800.
Bleaching the pulp and modifying the fiber. Comprises oxygen delignification, acid treatment, ozone bleaching, alkaline fiber modification treatment and pressure hydrogen peroxide bleaching. In oxygen delignification, the initial slurry concentration range was 10%, the alkali dosage was 2%, the oxygen pressure was 0.8MPa, the temperature was 100 ℃, and the holding time was 70 minutes. And after oxygen delignification treatment, carrying out acid treatment on the initial slurry, wherein sulfuric acid is adopted for the acid treatment, and in the acid treatment process, the concentration of the initial slurry is 10%, the pH value is 2, the temperature is 80 ℃, and the time is 70 minutes. After the acid treatment, the initial pulp was subjected to ozone bleaching, with 1.0% ozone usage at 50 ℃. After the ozone reaction is finished, alkali fiber modification treatment is carried out, wherein the alkali consumption is 1%, the acrylamide consumption is 0.05%, the temperature is 70 ℃, the concentration of initial slurry is 10%, and the time is 40 minutes. After the treatment, a hydrogen peroxide bleaching (PO) under pressure of 0.2MPa, at a concentration of 10% in the initial slurry, at 110 ℃ for 60 minutes was carried out.
And obtaining the lyocell fiber dissolving pulp after the steps are finished.
Example 2:
the wood chips are prehydrolyzed. Taking 100g of eucalyptus pieces, and carrying out prehydrolysis by adopting prehydrolysis steam hydrolysis at 150 ℃ for 60min.
And (5) cooking the wood chips. A sulfate cooking method is adopted, the liquor ratio is 4, the using amount of NaOH is 20%, the vulcanization degree is 25%, and the cooking H factor is controlled to be 800.
Bleaching the pulp and modifying the fiber. Comprises oxygen delignification, acid treatment, ozone bleaching, alkaline fiber modification treatment and pressure hydrogen peroxide bleaching. In oxygen delignification, the initial slurry concentration range was 10%, the alkali dosage was 2%, the oxygen pressure was 0.8MPa, the temperature was 100 ℃, and the holding time was 70 minutes. After oxygen delignification treatment, carrying out acid treatment on the initial slurry, wherein sulfuric acid is adopted for the acid treatment, and in the acid treatment process, the concentration of the initial slurry is 10%, the pH value is 2, the temperature is 80 ℃, and the time is 70 minutes. After the acid treatment, the initial pulp was subjected to ozone bleaching, wherein the ozone dosage was 1.0% and the temperature was 50 ℃. After the ozone reaction, alkaline fiber modification treatment is carried out, wherein the alkali consumption is 1.5%, the acrylamide consumption is 0.1%, the temperature is 80 ℃, the concentration of initial slurry is 10%, and the time is 80 minutes. After the treatment, a hydrogen peroxide bleaching (PO) under pressure of 0.2MPa, at a concentration of 10% in the initial slurry, at 110 ℃ for 60 minutes was carried out.
And obtaining the lyocell fiber dissolving pulp after the steps are finished.
Example 3:
the wood chips are prehydrolyzed. Taking 100g of eucalyptus pieces, and carrying out prehydrolysis by adopting prehydrolysis steam hydrolysis at 150 ℃ for 60min.
And (5) cooking the wood chips. A sulfate cooking method is adopted, the liquor ratio is 4, the using amount of NaOH is 20%, the vulcanization degree is 25%, and the cooking H factor is controlled to be 800.
Bleaching the pulp and modifying the fiber. Comprises oxygen delignification, acid treatment, ozone bleaching, alkaline fiber modification treatment and pressure hydrogen peroxide bleaching. In the oxygen delignification, the concentration range of the initial slurry is 10%, the alkali dosage is 2%, the oxygen pressure is 0.8MPa, the temperature is 100 ℃, and the heat preservation time is 70 minutes. After oxygen delignification treatment, carrying out acid treatment on the initial slurry, wherein sulfuric acid is adopted for the acid treatment, and in the acid treatment process, the concentration of the initial slurry is 10%, the pH value is 2, the temperature is 80 ℃, and the time is 70 minutes. After the acid treatment, the initial pulp was subjected to ozone bleaching, wherein the ozone dosage was 1.0% and the temperature was 50 ℃. After the ozone reaction is finished, alkaline fiber modification treatment is carried out, the alkali consumption is 2%, the acrylamide consumption is 0.2%, the temperature is 90 ℃, the concentration of initial slurry is 10%, and the time is 120 minutes. After the treatment, a hydrogen peroxide bleaching (PO) under pressure of 0.2MPa, at a concentration of 10% in the initial slurry, at 110 ℃ for 60 minutes was carried out.
And obtaining the lyocell fiber dissolving pulp after the steps are finished.
Comparative example:
the wood chips are prehydrolyzed. Taking 100g of eucalyptus pieces, and carrying out prehydrolysis by adopting prehydrolysis steam hydrolysis at 150 ℃ for 60min.
And (5) cooking the wood chips. A sulfate cooking method is adopted, the liquor ratio is 4, the using amount of NaOH is 20%, the vulcanization degree is 25%, and the cooking H factor is controlled to be 800.
And (4) bleaching the pulp. Including oxygen delignification, acid treatment, ozone bleaching, alkali treatment, pressure hydrogen peroxide bleaching. In the oxygen delignification, the concentration range of the initial slurry is 10%, the alkali dosage is 2%, the oxygen pressure is 0.8MPa, the temperature is 100 ℃, and the heat preservation time is 70 minutes. After oxygen delignification, the initial slurry is subjected to acid treatment, wherein sulfuric acid is adopted for the acid treatment, and in the acid treatment process, the concentration of the initial slurry is 10%, the pH value is 2, the temperature is 80 ℃, and the time is 70 minutes. After the acid treatment, the initial pulp was subjected to ozone bleaching, wherein the ozone dosage was 1.0% and the temperature was 50 ℃. After the ozone reaction was completed, alkali treatment was carried out for 40 minutes at 70 ℃ with an alkali content of 1%. After the alkali treatment, a hydrogen peroxide bleaching (PO) was carried out under a pressure of 0.2MPa, at a temperature of 110 ℃ and for a bleaching time of 60 minutes at an initial slurry concentration of 10%.
And obtaining the lyocell fiber dissolving pulp after the steps are finished.
The quality indexes of the pulp of the above examples and comparative examples are as follows:
the data show that the method can greatly improve the Fock reaction performance of the pulp, namely the dissolving capacity of the pulp is greatly enhanced, and the alpha cellulose content, the alkalinity resistance and the whiteness of the pulp are all improved to a certain extent.
According to the method, the cellulose is modified in the pulp bleaching process, hydrogen bond bonding among cellulose molecular chains is reduced, and the rigid structure of a crystalline region is destroyed, so that an NMMO solution can permeate into the interior of the fiber more quickly during the preparation of the lyocell fiber, the dissolving capacity of the fiber is improved, the fiber after the modification treatment has better bleachability in the bleaching process at the later stage of dissolving pulp, the bleaching effect is better, and the dissolving pulp prepared from the modified fiber is superior to unmodified pulp in the indexes such as alpha cellulose proportion, reaction performance, whiteness, metal ion content, resin content and the like.
Based on the same inventive concept, the application also provides a dissolving pulp which is prepared by the preparation method of the lyocell dissolving pulp in any embodiment, so that the lyocell dissolving pulp can be improved to a certain extent in indexes such as alpha cellulose proportion, reactivity, whiteness, metal ion content, resin content and the like.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A method for preparing lyocell dissolving pulp, characterized in that the method for preparing lyocell dissolving pulp comprises:
obtaining wood chips to be treated, and carrying out prehydrolysis on the wood chips to be treated;
cooking the pre-hydrolyzed wood chips to be treated to obtain initial slurry;
bleaching the initial pulp to obtain the lyocell dissolving pulp; wherein the initial slurry is subjected to a fiber modification treatment during the bleaching treatment.
2. The method for producing lyocell dissolving pulp according to claim 1, wherein said bleaching treatment is performed on said initial pulp liquid to obtain said lyocell dissolving pulp; wherein the step of subjecting the initial slurry to a fiber modification treatment during the bleaching treatment comprises:
subjecting the initial slurry to a first bleaching treatment;
carrying out fiber modification treatment on the initial slurry after the first bleaching treatment;
and carrying out second bleaching treatment on the initial pulp after the fiber modification treatment to obtain the lyocell dissolving pulp.
3. The method of producing lyocell dissolving pulp according to claim 2, wherein the step of subjecting the initial pulp slurry after the first bleaching process to a fiber modification process comprises:
and (3) carrying out fiber modification treatment on the initial slurry after the first bleaching treatment by using sodium hydroxide and acrylamide.
4. The method for preparing lyocell dissolving pulp according to claim 3, wherein the step of subjecting the initial pulp after the first bleaching treatment to a fiber modification treatment by sodium hydroxide and acrylamide comprises:
within a preset temperature, carrying out fiber modification treatment for a preset time length on the initial slurry after the first bleaching treatment at a preset concentration through sodium hydroxide and acrylamide;
wherein the range of the preset temperature is 70-90 ℃, the range of the preset concentration is 5-10%, and the range of the preset duration is 30-120 minutes; the alkali consumption range of the sodium hydroxide is 1.0-2.0%, and the consumption range of the acrylamide is 0.05-0.20%.
5. The method of producing lyocell dissolving pulp according to claim 2, wherein the step of subjecting the initial pulp slurry to a first bleaching treatment comprises:
subjecting the initial slurry to oxygen delignification;
carrying out acid treatment on the initial slurry after oxygen delignification treatment by using sulfuric acid;
carrying out ozone bleaching treatment on the initial slurry after the acid treatment;
the step of performing a second bleaching treatment on the initial slurry after the fiber modification treatment to obtain the dissolving pulp comprises the following steps:
and carrying out at least one section of pressure hydrogen peroxide bleaching treatment on the initial slurry after the fiber modification treatment to obtain the lyocell dissolving pulp.
6. The method for producing lyocell dissolving pulp according to claim 5, wherein,
the dosage range of the ozone for the ozone bleaching treatment is 0.2-1.5%, and the temperature range is 30-70 ℃;
the oxygen pressure range of the pressure hydrogen peroxide bleaching treatment is 0.20-0.30MPa, the concentration range of initial slurry during the pressure hydrogen peroxide bleaching treatment is 10-20%, the temperature range is 105-120 ℃, and the bleaching time range is 60-90 minutes;
the concentration range of the initial slurry during the oxygen delignification treatment is 10-20%, the alkali dosage range is 1.5-4.5%, the oxygen pressure range is 0.8-1.0MPa, the temperature range is 95-110 ℃, and the heat preservation time range is 60-80 minutes;
the concentration range of the initial slurry during the acid treatment is 10-20%, the pH range is 1.5-3.5, the temperature range is 70-80 ℃, and the time range is 60-80 minutes.
7. The method for preparing lyocell dissolving pulp according to claim 1, wherein the step of obtaining wood chips to be treated and pre-hydrolyzing the wood chips to be treated comprises:
obtaining wood chips to be treated, and performing presteaming hydrolysis on the wood chips to be treated;
wherein the temperature range of the pre-gas steam hydrolysis is 130-170 ℃, and the time range is 20-80 minutes.
8. The method for preparing lyocell dissolving pulp according to claim 1, wherein the step of obtaining wood chips to be treated and pre-hydrolyzing the wood chips to be treated comprises:
obtaining wood chips to be treated, and carrying out water impregnation prehydrolysis on the wood chips to be treated, wherein the temperature range of the water impregnation prehydrolysis is 130-170 ℃, and the time range is 20-80 minutes.
9. A method of producing lyocell dissolving pulp according to claim 1, characterized in that the step of cooking the pre-hydrolysed wood chips to be treated to obtain an initial pulp comprises:
carrying out sulfate cooking on the wood chips to be treated after prehydrolysis through sodium hydroxide and sodium sulfide to obtain initial slurry;
wherein, the liquor ratio range of the sulfate cooking is 3-5, the dosage range of sodium hydroxide is 17-21%, the range of the sulfuration degree is 20-30%, and the cooking H factor is controlled within the range of 550-1300.
10. Lyocell dissolving pulp characterized by being produced by the method for producing a Lyocell dissolving pulp according to any one of claims 1 to 9.
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| CN114775324A (en) * | 2022-03-17 | 2022-07-22 | 金光纸业(中国)投资有限公司 | Dissolving pulp and preparation method thereof |
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| CN114775324A (en) * | 2022-03-17 | 2022-07-22 | 金光纸业(中国)投资有限公司 | Dissolving pulp and preparation method thereof |
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