CN110629576B - Method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp - Google Patents
Method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp Download PDFInfo
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- 241000219000 Populus Species 0.000 title claims abstract description 77
- 238000004061 bleaching Methods 0.000 title claims abstract description 74
- 229920000875 Dissolving pulp Polymers 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 51
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 title claims abstract description 49
- 239000001301 oxygen Substances 0.000 claims abstract description 31
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 31
- 238000005406 washing Methods 0.000 claims abstract description 23
- 230000008569 process Effects 0.000 claims abstract description 20
- 239000002994 raw material Substances 0.000 claims abstract description 14
- 238000009897 hydrogen peroxide bleaching Methods 0.000 claims abstract description 8
- 239000002002 slurry Substances 0.000 claims description 64
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 57
- 238000006243 chemical reaction Methods 0.000 claims description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 37
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 27
- 230000007935 neutral effect Effects 0.000 claims description 24
- 238000010411 cooking Methods 0.000 claims description 20
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 18
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 16
- 239000003513 alkali Substances 0.000 claims description 10
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000004115 Sodium Silicate Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 8
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 8
- 238000004073 vulcanization Methods 0.000 claims description 8
- 239000002023 wood Substances 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 7
- 239000011734 sodium Substances 0.000 claims description 7
- 239000002738 chelating agent Substances 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 229920000297 Rayon Polymers 0.000 claims description 4
- 229920003086 cellulose ether Polymers 0.000 claims description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 3
- 238000004321 preservation Methods 0.000 claims description 3
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- 238000002360 preparation method Methods 0.000 claims description 2
- 239000002351 wastewater Substances 0.000 abstract description 8
- 238000005516 engineering process Methods 0.000 abstract description 7
- 231100000167 toxic agent Toxicity 0.000 abstract description 4
- 239000003440 toxic substance Substances 0.000 abstract description 4
- 238000004064 recycling Methods 0.000 abstract 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 12
- 239000000203 mixture Substances 0.000 description 9
- 230000009920 chelation Effects 0.000 description 7
- 239000002655 kraft paper Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000005520 cutting process Methods 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 239000000835 fiber Substances 0.000 description 4
- 239000001095 magnesium carbonate Substances 0.000 description 4
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 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 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- 229920002488 Hemicellulose Polymers 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 229920002678 cellulose Polymers 0.000 description 3
- 239000001913 cellulose Substances 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- -1 diethyl triaminepentaacetic acid Chemical compound 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229920005610 lignin Polymers 0.000 description 2
- 238000004537 pulping Methods 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 229920006221 acetate fiber Polymers 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- OSVXSBDYLRYLIG-UHFFFAOYSA-N chlorine dioxide Inorganic materials O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002027 dichloromethane extract Substances 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1068—Bleaching ; Apparatus therefor with O2
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C1/00—Pretreatment of the finely-divided materials before digesting
- D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
- D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/222—Use of compounds accelerating the pulping processes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1042—Use of chelating agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1073—Bleaching ; Apparatus therefor with O3
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
- D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
Abstract
The invention relates to a method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp, which comprises the following steps: preparing poplar sulfate pulp by using poplar as a raw material and adopting a prehydrolysis sulfate method; carrying out ZOQP bleaching on the poplar sulfate pulp to obtain dissolving pulp; wherein, Z-ozone bleaching, O-oxygen delignification, Q-chelation treatment and P-hydrogen peroxide bleaching. The whole process of preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp realizes the recycling of washing and bleaching waste water and has zero discharge; the high-quality dissolving pulp produced by the technology has no toxic substance residue, each index exceeds the qualified product requirement in the industry standard of dissolving pulp (QB/T4898-.
Description
Technical Field
The invention belongs to the field of papermaking technology and new materials, and particularly relates to a method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
The dissolving pulp is composed of high-purity cellulose and is used for manufacturing materials such as viscose, acetate, nitrocellulose, cellulose ether and the like, and important quality indexes of the dissolving pulp mainly comprise alpha-cellulose content, hemicellulose content, viscosity, molecular weight distribution and the like. In order to improve the product quality, the contents of hemicellulose, lignin, ash and metal ions in the dissolving pulp are strictly controlled, and the reactivity and the cellulose molecular weight distribution of the pulp are also required to be improved.
Broadleaf wood has become the main material of dissolving pulp production at presentA fiber raw material. The prehydrolysis sulfate process has become the main dissolving pulp production process, oxygen-alkali delignification and ClO2The popularization of bleaching promotes the application of green bleaching processes such as ECF, light ECF and even TCF in dissolving pulp production.
However, the inventor finds that: compared with the pulp of grass raw materials, the pulp of wood raw materials has poorer bleaching property and higher bleaching difficulty. Domestic dissolving pulp enterprises still use the traditional chlorine bleaching or element-free chlorine bleaching (ECF) technology to produce dissolving pulp. However, the traditional chlorine-containing bleaching has the defects of large water consumption for bleaching, difficult treatment of wastewater, existence of carcinogenic substances such as dioxin and the like, and the like; ECF bleaching has the problems of higher production cost, generation of a large amount of acidic substances in the reaction, lower pH value at the bleaching end point, strict requirements on equipment and the like. Limited by factors such as cost, product quality and the like, the TCF bleaching effect in the prior process of preparing dissolving pulp by wood raw materials still difficultly meets the requirement of practical production, and the alkali resistance and D resistance65The main indexes such as brightness and the like are difficult to meet the requirements of qualified products, and the cost is high.
Disclosure of Invention
In order to overcome the problems, the invention provides an environment-friendly method for preparing dissolving pulp by bleaching poplar prehydrolysis sulfate pulp, each index exceeds the requirements of qualified products in the industry standard of the dissolving pulp (QB/T4898-.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp comprises the following steps:
preparing poplar sulfate pulp by using poplar as a raw material and adopting a prehydrolysis sulfate method;
carrying out ZOQP bleaching on the poplar sulfate pulp to obtain dissolving pulp;
wherein, Z-ozone bleaching, O-oxygen delignification, Q-chelation treatment and P-hydrogen peroxide bleaching.
The research of the application finds that: the method adopts ZOQP bleaching sequence chlorine-free bleaching for poplar sulfate pulp pretreated by hot water, can meet the index requirement of qualified dissolving pulp products under the condition of low drug dosage, obtains higher dissolving pulp yield, reduces production cost and bleaching sewage discharge and does not generate organic halide.
In some embodiments, the prehydrolysis sulfate process comprises: hot water pretreatment and sulfate cooking. According to the invention, poplar chips are used as raw materials, pulping is carried out by a sulfate method, then a novel green and environment-friendly total chlorine-free bleaching (TCF) ZOQP method is adopted, the waste water generated by bleaching does not contain harmful substances such as dioxin, AOX and the like, the COD content of the waste water is greatly reduced, and the cyclic use of the washing and bleaching waste water can be realized, and zero discharge is realized; the high-quality dissolving pulp produced by the technology has no toxic substance residue, each index exceeds the qualified product requirement in the industry standard of dissolving pulp (QB/T4898-.
In some embodiments, the hot water pretreatment comprises the following specific steps: mixing the wood chips and water according to the liquid ratio of 1:4-1:7, heating to 150-. Reduces the content of hemicellulose in the raw material, destroys the primary wall of the fiber and is beneficial to the subsequent cooking of the pulp.
In some embodiments, the specific steps of the kraft cooking are: the liquid ratio is 1:4-1:7, the temperature is 150-2Calculated by O) 20-25 percent, the degree of vulcanization is 20-25 percent, and the cooking time is 60-100 min. Each index of the subsequently prepared dissolving pulp exceeds the requirement of qualified products in the industry standard (QB/T4898-2015) of the dissolving pulp, and other indexes except the dichloromethane extract exceed the indexes of superior products.
The research of the application finds that: the first O and the second Z are beneficial to removing residual lignin in the pulp after cooking and obtaining high-whiteness dissolving pulp by subsequent bleaching, and the first Z and the second O can reduce the loss of cellulose under the condition of ensuring that the high whiteness is higher than a qualified product, and the yield of the dissolving pulp is higher. Thus, in some embodiments, the specific steps of segment Z are: adjusting the pulp concentration of poplar sulfate pulp to 25-30%, adjusting the pH to 1.5-3.0, the ozone amount to 1.0-3.0%, the diethyl triaminepentaacetic acid (DTPA) amount to 0.3-0.7%, the temperature to 20-35 ℃, uniformly mixing, reacting for 10-30min, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 8-15%, thereby improving the yield and whiteness of the dissolving pulp.
In some embodiments, the specific steps of the O-segment are: placing the slurry in a sealed environment after the Z section is floated, introducing oxygen until the oxygen pressure is 0.4-0.8Mpa, the using amount of NaOH is 1.0-3.0%, and MgCO is added3The dosage is 0.3-0.7%, the reaction is carried out for 30-50min at the temperature of 90-110 ℃, after the bleaching is finished, the pulp is washed to be neutral, and the pulp concentration is adjusted to be 8-15%. Addition of MgCO3The whiteness of the dissolving pulp is improved, the breaking length and the tearing factor are improved, and the pentosan content is reduced.
In some embodiments, segment Q: and (3) placing the slurry after the O section treatment in a sealed environment, adding 0.2-0.6% of chelating agent DTPA to uniformly mix the slurry and the DTPA, and performing chelating treatment at 60-80 ℃ for 20-40 min. The chelation treatment improves the whiteness of the dissolving pulp and the bleachability of the P-stage.
In some embodiments, P segment: after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O21.0-3.0% of the use amount, 0.4-0.9% of NaOH, 1.0-2.0% of sodium silicate, 0.1-0.3% of magnesium sulfate, 80-100 ℃ of the temperature and 70-100min of time, taking out the slurry after the reaction is finished, washing the slurry to be neutral, and drying the slurry to obtain the dissolving slurry. The prepared dissolving pulp has high quality and no toxic substance residue, each index exceeds the requirements of qualified products in the industry standard (QB/T4898-.
The invention also provides dissolving pulp prepared by any one of the methods.
The invention also provides application of the dissolving pulp in preparation of viscose, acetate, nitrate or cellulose ether.
The invention has the beneficial effects that:
(1) the whole process of preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp adopts hot water, oxygen, ozone, hydrogen peroxide, a small amount of alkali and a trace amount of other auxiliary agents, the waste water generated by bleaching does not contain harmful substances such as dioxin, AOX and the like, the COD content of the waste water is greatly reduced, the cyclic use of the washing and bleaching waste water can be realized, and zero discharge is realized; the high-quality dissolving pulp produced by the technology has no toxic substance residue, each index exceeds the qualified product requirement in the industry standard of dissolving pulp (QB/T4898-. The technology conforms to the industrial policies of national resource conservation, energy conservation, emission reduction and green development.
(2) The operation method is simple, low in equipment requirement, low in cost, universal and easy for large-scale production.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
As introduced by the background technology, the method aims at the problems of poor TCF bleaching effect and high cost of the existing wood dissolving pulp. Therefore, the invention provides an environment-friendly method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp, which takes poplar chips as raw materials and comprises the following steps:
cutting the naturally air-dried and impurity-removed poplar into poplar pieces with the length of 3-6cm and the thickness of 2-5mm, and firstly, carrying out hot water pretreatment on the poplar pieces: mixing the wood chips and water according to a liquid ratio of 1:4-1:7, heating to 150-; subsequently, the pretreated poplar chips were cooked by a sulfate process under the following conditions: liquid ratioIs 1:4-1:7, the temperature is 150-180 ℃, and the alkali amount (by Na)2Calculated by O) 20-25 percent, the degree of vulcanization is 20-25 percent, the cooking time is 60-100min, and after the cooking is finished, the poplar sulfate pulp is obtained by washing and concentrating. Then carrying out full chlorine-free ZOQP (Z-ozone bleaching, O-oxygen delignification, Q-chelation treatment and P-hydrogen peroxide bleaching) bleaching on the poplar sulfate pulp. A Z section: adjusting the pulp concentration of poplar sulfate pulp to 25-30%, adjusting the pH to 1.5-3.0, the using amount of ozone to 1.0-3.0%, the using amount of diethyl triaminepentaacetic acid (DTPA) to 0.3-0.7%, and the temperature to 20-35 ℃, uniformly mixing, reacting for 10-30min, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 8-15%. And (4) O section: placing the slurry in a sealed environment after the Z section is floated, introducing oxygen until the oxygen pressure is 0.4-0.8Mpa, the using amount of NaOH is 1.0-3.0%, and MgCO is added3The dosage is 0.3-0.7%, the reaction is carried out for 30-50min at the temperature of 90-110 ℃, after the bleaching is finished, the pulp is washed to be neutral, and the pulp concentration is adjusted to be 8-15%. And a Q section: and (3) placing the slurry after the O section treatment in a sealed environment, adding 0.2-0.6% of chelating agent DTPA to uniformly mix the slurry and the DTPA, and performing chelating treatment at 60-80 ℃ for 20-40 min. And a P section: after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O21.0-3.0% of the use amount, 0.4-0.9% of NaOH, 1.0-2.0% of sodium silicate, 0.1-0.3% of magnesium sulfate, 80-100 ℃ of the temperature and 70-100min of time, taking out the slurry after the reaction is finished, washing the slurry to be neutral, drying the slurry to obtain dissolving slurry, and measuring various indexes of the dissolving slurry.
The chemical reagent grades used in the patent of the invention are all chemically pure.
The invention takes poplar chips as raw materials, after hot water pretreatment and sulfate pulping, the dissolving pulp is prepared by adopting a chlorine-free ZOQP bleaching process, and the detailed steps are as follows:
(1) preparing materials: cutting the naturally air-dried and impurity-removed poplar into poplar chips with the length of 3-6cm and the thickness of 2-5 mm.
(2) Pretreating poplar chips with hot water: mixing the wood chips and water according to the liquid ratio of 1:4-1:7, heating to 150-.
(3) Boiling poplar by a sulfate method: the liquid ratio is 1:4-1:7, the heat preservation temperature is 150-180 ℃, and the alkali amount (by Na)2Calculated by O) 20-25 percent, the vulcanization degree is 20-25 percent, the boiling time is 60-100min, the poplar slices pretreated by hot water are boiled, and after the boiling is finished, the kraft pulp pretreated by the poplar hot water is obtained by concentration and washing.
(4) Ozone bleaching (stage Z): adjusting the pulp concentration of the hot water pretreated kraft pulp of poplar to 25-30%, adjusting the pH value to 1.5-3.0, the ozone amount to 1.0-3.0%, the diethyl triaminepentaacetic acid (DTPA) amount to 0.3-0.7%, the temperature to 20-35 ℃, mixing uniformly, reacting for 10-30min, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 8-15%.
(5) Oxygen delignification (O stage): placing the slurry in a sealed environment after the Z section is floated, introducing oxygen until the oxygen pressure is 0.4-0.8Mpa, the using amount of NaOH is 1.0-3.0%, and MgCO is added3The dosage is 0.3-0.7%, the pulp is stirred at the speed of 60r/min at the temperature of 90-110 ℃ and reacts for 30-50min, and after bleaching, the pulp is washed to be neutral, and the pulp concentration is adjusted to be 8-15%.
(6) Chelation treatment (Q stage): and (3) placing the slurry after the O section treatment in a sealed reaction kettle, adding 0.2-0.6% of chelating agent DTPA to uniformly mix the slurry and the DTPA, and chelating at 60-80 ℃ for 20-40 min.
(7) Hydrogen peroxide bleaching (P stage): after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O21.0-3.0% of the use amount, 0.4-0.9% of NaOH, 1.0-2.0% of sodium silicate, 0.1-0.3% of magnesium sulfate, 80-100 ℃ of the temperature and 70-100min of time, taking out the slurry after the reaction is finished, washing the slurry to be neutral, drying the slurry to obtain dissolving slurry, and measuring various indexes of the dissolving slurry.
The method comprises the following steps:
(1) removing impurities from naturally air-dried poplar, and cutting into poplar chips with length of 3-6cm and thickness of 2-5 mm.
(2) Adding the poplar chips in the step (1) and water into a reaction kettle according to the liquid ratio of 1:4-1:7, heating to 150-.
(3) The poplar chips pretreated in the step (2) are subjected to heat preservation at the temperature of 150-180 ℃ and alkali consumption (Na) at the liquid ratio of 1:4-1:72Calculated as O) 20-25 percent and the vulcanization degree is 20-25 percent, the mixture is cooked for 60-100min, and after the cooking is finished, the mixture is washedAnd washing and concentrating to obtain the poplar hot water pretreated kraft pulp.
(4) Carrying out ozone bleaching on the pulp obtained in the step (3) (Z stage): the conditions are as follows: adjusting the pH value of the slurry to 1.5-3.0 by using acetic acid, adjusting the using amount of ozone to 1.0-3.0%, adjusting the using amount of DTPA to 0.3-0.7%, adjusting the concentration of slurry to 25-30%, adjusting the temperature to 20-35 ℃, adjusting the stirring speed to 60r/min, adjusting the reaction time to 10-30min, allowing the redundant ozone generated in the reaction process to enter an absorption device filled with KI solution through an air outlet for absorption, after the reaction is finished, washing the slurry to be neutral by using water, and adjusting the concentration of the slurry to 8-15%.
(5) Subjecting the slurry of step (4) to oxygen delignification (O stage) under the following conditions: introducing oxygen gas until oxygen pressure is 0.4-0.8Mpa, NaOH dosage is 1.0-3.0%, and MgCO3The dosage is 0.3-0.7%, the pulp is stirred at the speed of 60r/min at the temperature of 90-110 ℃ and reacts for 30-50min, and after bleaching, the pulp is washed to be neutral, and the pulp concentration is adjusted to be 8-15%.
(6) And (3) placing the slurry obtained in the step (5) into a closed reaction kettle for chelation treatment (Q section), adding 0.3-0.6% of diethyltriaminepentaacetic acid (DTPA), performing chelation treatment in a water bath kettle at the temperature of 60-80 ℃ for 20-40min, and stirring at the speed of 60r/min to uniformly mix the slurry.
(7) After the reaction of the Q section is finished, hydrogen peroxide is directly added for bleaching (P section), and the process condition is H2O21.0-3.0 percent of dosage, 0.4-0.9 percent of NaOH, 1.0-2.0 percent of sodium silicate, 0.1-0.3 percent of dosage of magnesium sulfate, 80-100 ℃ of temperature and 70-100min of time, taking out slurry after the reaction is finished, and washing the slurry to be neutral.
(8) And (4) drying the slurry obtained in the step (7) to obtain dissolving slurry, which is mainly used for producing viscose fibers, acetate fibers, nitric acid fibers or cellulose ether.
The technical solution of the present application will be described below with specific examples. In the following examples, the percentages (%) are by mass.
Example 1: the method is characterized in that poplar chips are used as raw materials, are pretreated by hot water and are pulped by a sulfate method, and are bleached by totally chlorine-free ZOQP to prepare dissolving pulp, and the dissolving pulp is prepared by the following steps.
(1) Preparing materials: cutting the naturally air-dried and impurity-removed poplar into poplar chips with the length of 3-6cm and the thickness of 2-5 mm.
(2) Pretreating poplar chips with hot water: adding poplar chips and water into a reaction kettle according to the liquid ratio of 1:5, heating to 165 ℃, and preserving heat for 90 min.
(3) Boiling poplar by a sulfate method: the liquid ratio is 1:5, and the amount of alkali (as Na)2O)22 percent, the vulcanization degree is 24 percent, the cooking temperature is 165 ℃, the cooking time is 90min, the poplar chips pretreated by hot water are cooked, and after the cooking is finished, the poplar sulfate pulp is obtained by washing and concentrating.
(4) Ozone bleaching (stage Z): adjusting the pulp concentration of poplar sulfate pulp to 28%, placing the pulp in a reactor, adjusting the ozone content to 2% and the DTPA content to 0.5%, adjusting the pH value to 2.5 with acetic acid, stirring the pulp at the temperature of 25 ℃ at the speed of 60r/min, reacting for 20min, allowing the redundant ozone generated in the process to enter an absorber filled with KI solution through an air outlet for absorption, washing the pulp to be neutral after the reaction is finished, and concentrating the pulp until the pulp concentration is 10%.
(5) Oxygen delignification (O stage): placing the slurry in an oxygen bleaching tank after the Z section bleaching, introducing oxygen until the oxygen pressure is 0.6Mpa, the using amount of NaOH is 2.5 percent, and MgCO3The dosage is 0.5%, the pulp is stirred in an oxygen bleaching tank at 100 ℃ at the speed of 60r/min, the reaction is carried out for 40min, after the bleaching is finished, the pulp is washed to be neutral by water, and the pulp concentration is adjusted to be 10%.
(6) Chelation treatment (Q stage): and (3) placing the slurry after the O section treatment in a sealed reaction kettle, adding 0.5% chelating agent DTPA, stirring at 60r/min to uniformly mix the slurry and the DTPA, and chelating at 70 ℃ for 30 min.
(7) Hydrogen peroxide bleaching (P stage): after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O2The using amount of the sodium hydroxide is 2.0 percent, the using amount of NaOH is 0.8 percent, the using amount of sodium silicate is 1.5 percent, the using amount of magnesium sulfate is 0.2 percent, the temperature is 90 ℃, the time is 90min, after the reaction is finished, the slurry is taken out, washed to be neutral, dried to obtain dissolving slurry, and all indexes of the dissolving slurry are measured.
TABLE 1 comparison of index of dissolving pulp prepared by ZOQP bleaching of poplar prehydrolysis kraft pulp with index of industry standard
Example 2: the method is characterized in that poplar chips are used as raw materials, are pretreated by hot water and are pulped by a sulfate method, and are bleached by totally chlorine-free ZOQP to prepare dissolving pulp, and the dissolving pulp is prepared by the following steps.
(1) Preparing materials: cutting the naturally air-dried and impurity-removed poplar into poplar chips with the length of 3-6cm and the thickness of 2-5 mm.
(2) Pretreating poplar chips with hot water: adding poplar chips and water into a reaction kettle according to the liquid ratio of 1:6, heating to 170 ℃, and preserving heat for 70 min.
(3) Boiling poplar by a sulfate method: the liquid ratio is 1:5, and the amount of alkali (as Na)2O)20 percent, the vulcanization degree is 22 percent, the cooking temperature is 170 ℃, the cooking time is 100min, the poplar chips pretreated by hot water are cooked, and after the cooking is finished, the poplar sulfate pulp is obtained by washing and concentrating.
(4) Ozone bleaching (stage Z): adjusting the pulp concentration of poplar sulfate pulp to 25%, placing the pulp in a reactor, adjusting the ozone content to 1% and the DTPA content to 0.3%, adjusting the pH value to 2.0 with acetic acid, stirring the pulp at the temperature of 20 ℃ at the speed of 60r/min, reacting for 30min, allowing the redundant ozone generated in the process to enter an absorber filled with KI solution through an air outlet for absorption, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 12%.
(5) Oxygen delignification (O stage): placing the slurry in an oxygen bleaching tank after the Z section bleaching, introducing oxygen until the oxygen pressure is 0.4Mpa, the using amount of NaOH is 1.5 percent, and MgCO3The dosage is 0.3%, the pulp is stirred in an oxygen bleaching tank at 90 ℃ at the speed of 60r/min, the reaction is carried out for 50min, after the bleaching is finished, the pulp is washed to be neutral by water, and the pulp concentration is adjusted to be 12%.
(6) Chelation treatment (Q stage): and (3) placing the slurry after the O section treatment in a sealed reaction kettle, adding 0.3% chelating agent DTPA, stirring at 60r/min to uniformly mix the slurry and the DTPA, and chelating at 60 ℃ for 40 min.
(7) Hydrogen peroxide bleaching (P stage): after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O2The using amount of the sodium hydroxide is 1.5%, the using amount of NaOH is 0.6%, the using amount of sodium silicate is 1.0%, the using amount of magnesium sulfate is 0.1%, the temperature is 95 ℃, the time is 100min, after the reaction is finished, the slurry is taken out, washed to be neutral, dried to obtain dissolving slurry, and all indexes of the dissolving slurry are measured.
TABLE 2 comparison of index of dissolving pulp prepared by ZOQP bleaching of poplar prehydrolysis kraft pulp with index of industry Standard
Example 3: the method is characterized in that poplar chips are used as raw materials, are pretreated by hot water and are pulped by a sulfate method, and are bleached by totally chlorine-free ZOQP to prepare dissolving pulp, and the dissolving pulp is prepared by the following steps.
(1) Preparing materials: cutting the naturally air-dried and impurity-removed poplar into poplar chips with the length of 3-6cm and the thickness of 2-5 mm.
(2) Pretreating poplar chips with hot water: adding poplar chips and water into a reaction kettle according to the liquid ratio of 1:4, heating to 175 ℃, and preserving heat for 60 min.
(3) Boiling poplar by a sulfate method: the liquid ratio is 1:5, and the amount of alkali (as Na)2O)25 percent, the vulcanization degree is 25 percent, the cooking temperature is 160 ℃, the cooking time is 80min, the poplar chips pretreated by hot water are cooked, and after the cooking is finished, the poplar sulfate pulp is obtained by washing and concentrating.
(4) Ozone bleaching (stage Z): adjusting the pulp concentration of poplar sulfate pulp to 30%, placing the pulp in a reactor, adjusting the ozone content to 3% and the DTPA content to 0.7%, adjusting the pH value to 3.0 with acetic acid, stirring the pulp at the temperature of 25 ℃ at the speed of 60r/min, reacting for 10min, allowing the redundant ozone generated in the process to enter an absorber filled with KI solution through an air outlet for absorption, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 15%.
(5) Oxygen delignification (O stage): placing the slurry in oxygen bleaching tank, introducing oxygen until oxygen pressure is 0.8Mpa, NaOH content is 3.5%, and MgSO4The dosage is 0.7%, the pulp is stirred in an oxygen bleaching tank at 110 ℃ at the speed of 60r/min, the reaction is carried out for 30min, after the bleaching is finished, the pulp is washed to be neutral by water, and the pulp concentration is adjusted to be 15%.
(6) Chelation treatment (Q stage): and (3) placing the slurry subjected to O section treatment in a sealed reaction kettle, adding 0.6% DTPA, stirring at 60r/min to uniformly mix the slurry and the DTPA, and chelating at 80 ℃ for 20 min.
(7) Hydrogen peroxide bleaching (P stage): after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O2The using amount of the sodium hydroxide is 3.0 percent, the using amount of NaOH is 1.0 percent, the using amount of sodium silicate is 2.0 percent, the using amount of magnesium sulfate is 0.3 percent, the temperature is 95 ℃, the time is 80min, after the reaction is finished, the slurry is taken out, washed to be neutral, dried to obtain dissolving slurry, and all indexes of the dissolving slurry are measured.
TABLE 3 comparison of index of dissolving pulp prepared by ZOQP bleaching of poplar kraft pulp with index of industry standard
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. Although the present invention has been described with reference to the specific embodiments, it should be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (4)
1. A method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp is characterized by comprising the following steps:
preparing poplar sulfate pulp by using poplar as a raw material and adopting a prehydrolysis sulfate method;
carrying out ZOQP bleaching on the poplar sulfate pulp to obtain dissolving pulp;
wherein, Z-ozone bleaching, O-oxygen delignification, Q-chelation treatment and P-hydrogen peroxide bleaching;
the prehydrolysis sulfate process comprises: hot water pretreatment and sulfate cooking;
the hot water pretreatment comprises the following specific steps: pretreating poplar chips with hot water: mixing the wood chips and water according to a liquid ratio of 1:4-1:7, heating to 150-;
the Z section comprises the following specific steps: adjusting the pulp concentration of poplar sulfate pulp to 25-30%, adjusting the pH value to 1.5-3.0, the using amount of ozone to 1.0-3.0%, the using amount of diethyltriamine pentaacetic acid (DTPA) to 0.3-0.7%, the temperature to 20-35 ℃, uniformly mixing, reacting for 10-30min, washing the pulp to be neutral after the reaction is finished, and concentrating until the pulp concentration is 8-15%;
the O section comprises the following specific steps: placing the slurry in a closed environment after the Z section is floated, introducing oxygen until the oxygen pressure is 0.4-0.8MPa, the using amount of NaOH is 1.0-3.0 percent, and MgCO is added3Stirring the pulp at the speed of 60r/min at the temperature of 90-110 ℃ with the dosage of 0.3-0.7%, reacting for 30-50min, washing the pulp to be neutral after bleaching, and adjusting the pulp concentration to 8-15%;
and a Q section: placing the slurry after O section treatment in a sealed reaction kettle, adding 0.2-0.6% of chelating agent DTPA to uniformly mix the slurry and DTPA, and chelating at 60-80 ℃ for 20-40 min;
and a P section: after the reaction of the Q section is finished, directly adding hydrogen peroxide into the slurry for bleaching, wherein the process condition is H2O21.0-3.0 percent of dosage, 0.4-0.9 percent of NaOH dosage, 1.0-2.0 percent of sodium silicate, 0.1-0.3 percent of magnesium sulfate dosage, 80-100 ℃ of temperature and 70-1 percent of time00min, after the reaction is finished, taking out the slurry, washing to be neutral, and drying to obtain the dissolving slurry.
2. The method for preparing dissolving pulp by completely chlorine-free bleaching of poplar sulfate pulp as claimed in claim 1, wherein the sulfate cooking comprises the following specific steps: boiling poplar by a sulfate method: the liquid ratio is 1:4-1:7, the heat preservation temperature is 150-180 ℃, and the alkali dosage is Na220-25% of O, 20-25% of vulcanization degree and 60-100min of cooking time.
3. Dissolving pulp prepared by the method of any one of claims 1-2.
4. Use of dissolving pulp according to claim 3 for the preparation of viscose, acetate, nitrate or cellulose ethers.
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| CN102912667A (en) * | 2012-10-17 | 2013-02-06 | 山东轻工业学院 | Method for producing dissolving pulp by using poplar slabs |
| CN102995478A (en) * | 2011-09-09 | 2013-03-27 | 吉林化纤集团有限责任公司 | Bleaching method for preparing high quality low pollution bamboo wood dissolving slurry |
| WO2013178608A1 (en) * | 2012-05-28 | 2013-12-05 | Södra Cell Ab | New process and a dissolving pulp manufactured by the process |
| CN104389215A (en) * | 2014-10-23 | 2015-03-04 | 广东比伦生活用纸有限公司 | Production method for environment-friendly and energy-saving living paper wood pulp |
| CN104452397A (en) * | 2014-11-21 | 2015-03-25 | 福建农林大学 | Method for improving reactive performance of prehydrolysis sulfate dissolving pulp |
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| EP0931874A1 (en) * | 1998-01-22 | 1999-07-28 | Degussa-Hüls Aktiengesellschaft | Pulp bleaching process including final stage treatment step with salt of peroxymonosulfuric acid |
| US8317975B2 (en) * | 2004-04-20 | 2012-11-27 | The Research Foundation Of The State University Of New York | Product and processes from an integrated forest biorefinery |
| JP4967451B2 (en) * | 2006-05-17 | 2012-07-04 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
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| CN102995478A (en) * | 2011-09-09 | 2013-03-27 | 吉林化纤集团有限责任公司 | Bleaching method for preparing high quality low pollution bamboo wood dissolving slurry |
| WO2013178608A1 (en) * | 2012-05-28 | 2013-12-05 | Södra Cell Ab | New process and a dissolving pulp manufactured by the process |
| CN102912667A (en) * | 2012-10-17 | 2013-02-06 | 山东轻工业学院 | Method for producing dissolving pulp by using poplar slabs |
| CN104389215A (en) * | 2014-10-23 | 2015-03-04 | 广东比伦生活用纸有限公司 | Production method for environment-friendly and energy-saving living paper wood pulp |
| CN104452397A (en) * | 2014-11-21 | 2015-03-25 | 福建农林大学 | Method for improving reactive performance of prehydrolysis sulfate dissolving pulp |
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Application publication date: 20191231 Assignee: SHANDONG TAIYANGZHIYE Co.,Ltd. Assignor: Qilu University of Technology (Shandong Academy of Sciences) Contract record no.: X2023980054386 Denomination of invention: A method for preparing dissolved pulp from poplar sulfate pulp by completely chlorine free bleaching Granted publication date: 20220412 License type: Common License Record date: 20240102 |