CN112726248A - Apocynum pulp for viscose fiber and its preparing process - Google Patents
Apocynum pulp for viscose fiber and its preparing process Download PDFInfo
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- CN112726248A CN112726248A CN202011588413.8A CN202011588413A CN112726248A CN 112726248 A CN112726248 A CN 112726248A CN 202011588413 A CN202011588413 A CN 202011588413A CN 112726248 A CN112726248 A CN 112726248A
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- 239000000835 fiber Substances 0.000 title claims abstract description 49
- 229920000297 Rayon Polymers 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 13
- 241000722949 Apocynum Species 0.000 title claims description 42
- 238000004061 bleaching Methods 0.000 claims abstract description 90
- 238000010306 acid treatment Methods 0.000 claims abstract description 74
- 239000003513 alkali Substances 0.000 claims abstract description 69
- 241000185686 Apocynum venetum Species 0.000 claims abstract description 58
- 238000005406 washing Methods 0.000 claims abstract description 30
- 238000010411 cooking Methods 0.000 claims abstract description 29
- 238000004537 pulping Methods 0.000 claims abstract description 18
- 239000000463 material Substances 0.000 claims abstract description 15
- 239000002562 thickening agent Substances 0.000 claims abstract description 14
- 238000002360 preparation method Methods 0.000 claims abstract description 12
- 239000004576 sand Substances 0.000 claims abstract description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 120
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 52
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 42
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 39
- 239000000460 chlorine Substances 0.000 claims description 39
- 229910052801 chlorine Inorganic materials 0.000 claims description 39
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 38
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 37
- 239000002253 acid Substances 0.000 claims description 33
- 238000004321 preservation Methods 0.000 claims description 33
- 239000002002 slurry Substances 0.000 claims description 26
- 238000010438 heat treatment Methods 0.000 claims description 20
- 239000004115 Sodium Silicate Substances 0.000 claims description 19
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 19
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 19
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 19
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 19
- 239000005708 Sodium hypochlorite Substances 0.000 claims description 14
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 14
- 235000006408 oxalic acid Nutrition 0.000 claims description 14
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 14
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 claims description 14
- 235000019982 sodium hexametaphosphate Nutrition 0.000 claims description 14
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 claims description 14
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 14
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 14
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims description 14
- 238000009874 alkali refining Methods 0.000 claims description 13
- 230000035484 reaction time Effects 0.000 claims description 13
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000002994 raw material Substances 0.000 abstract description 10
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 6
- 239000002351 wastewater Substances 0.000 abstract description 5
- 238000000746 purification Methods 0.000 abstract description 4
- 239000002699 waste material Substances 0.000 abstract description 4
- 238000007598 dipping method Methods 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000013386 optimize process Methods 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 2
- 239000007788 liquid Substances 0.000 abstract 1
- 238000007670 refining Methods 0.000 abstract 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 244000025254 Cannabis sativa Species 0.000 description 7
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 7
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 7
- 235000009120 camo Nutrition 0.000 description 7
- 235000005607 chanvre indien Nutrition 0.000 description 7
- 239000011487 hemp Substances 0.000 description 7
- 229920000609 methyl cellulose Polymers 0.000 description 6
- 239000001923 methylcellulose Substances 0.000 description 6
- 235000010981 methylcellulose Nutrition 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 6
- 238000005457 optimization Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000010908 plant waste Substances 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 238000004065 wastewater treatment Methods 0.000 description 2
- 241000208327 Apocynaceae Species 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000010025 steaming Methods 0.000 description 1
- 239000004753 textile 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
- 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
-
- 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
- D21C3/26—Multistage 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
- D21C9/1057—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
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
Abstract
The invention relates to the technical field of pulping, in particular to apocynum venetum pulp for viscose fibers and a preparation method thereof, which comprises the steps of preparing materials, preparing liquid alkali, cooking, washing with water after cooking, extruding pulp twice, transferring to a pulping machine, refining alkali, then performing pre-acid treatment, bleaching and acid treatment, washing after the acid treatment is finished, then selecting and removing sand, treating the washed apocynum venetum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp maker for papermaking to obtain the apocynum venetum pulp for the viscose fibers. The apocynum venetum pulp with the alpha fiber content of 93-93.5% is obtained by taking the apocynum venetum branches as the raw material and carrying out optimized process treatment, the dipping procedure is omitted, the pulp is directly cooked, the process flow is reduced, the waste of the raw material is reduced, no purification reagent is added in the preparation process, the COD of the wastewater is 33000 mg/L-40000 mg/L, the production cost is reduced, and the difficulty in treating the wastewater is reduced.
Description
Technical Field
The invention relates to the technical field of pulping, in particular to apocynum venetum pulp for viscose and a preparation method thereof.
Background
Apocynum venetum of Apocynaceae is a perennial root shrub wild high-grade fiber plant with strong stress resistance growing in saline-alkali, sandy beach and riverbank lands, and in recent years, the apocynum venetum bast fiber is outstanding in the wild plants, and the apocynum venetum stem skin is a good textile raw material, so that cultivation and domestication are introduced.
In the prior art, a preparation method of apocynum pulp is provided, wherein apocynum pulp is prepared by steaming and boiling apocynum skin fibers, pulp with the content of alpha fibers of 89-92% is obtained, and a high-efficiency penetrating agent (HY-PA) for purification is added besides a conventional reagent. The apocynum skin fiber is an important raw material for preparing the pulp, the prior art generally peels whole branches of the apocynum for improving the yield, the peeled skin fiber is used as the raw material for preparing the pulp, and the peeled hemp stems basically lose the use value. In the kendir branch, the kendir skin is about 20%, and the kendir stem is 80%. Most manufacturers peel off the hemp peel by using equipment, only the first fiber in the hemp peel is taken, and the hemp stalk is used as waste.
The main problems existing in the prior art are four points: firstly, the apocynum venetum has less fiber amount on the outer skin, and the apocynum venetum is used as a raw material for preparing the pulp, so that the pulp raw material source is less. Secondly, the hemp stalk after being taken out of the sheath basically loses the value for industrial use and needs to be further disposed. Thirdly, the penetrant added in the preparation process is organic matter, which causes difficulty in water treatment. Fourthly, the content of alpha-fibers of the pulp is not high enough.
Disclosure of Invention
The invention provides apocynum pulp for viscose fibers and a preparation method thereof, overcomes the defects of the prior art, and can effectively solve the problems of insufficient utilization of apocynum and high difficulty in wastewater treatment after pulping.
One of the technical schemes of the invention is realized by the following measures: a apocynum pulp used for viscose fiber is obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
The following is a further optimization or/and improvement of one of the above-mentioned technical solutions of the invention:
in the above step (5), the temperature is controlled to 60 ℃ to 70 ℃.
In the above step (7), the pH of the slurry is adjusted to 10.5 to 10.8.
And (4) adding hydrogen peroxide with the mass percentage concentration of 27.5 percent and the absolute dry pulp amount of 4.5 to 5.5 percent, sodium silicate with the absolute dry pulp amount of 3 to 6 percent and magnesium sulfate with the absolute dry pulp amount of 0.3 to 0.8 percent in the step (7).
The second technical scheme of the invention is realized by the following measures: a preparation method of apocynum venetum pulp used for viscose fibers comprises the following steps: the method comprises the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
The following is further optimization or/and improvement of the second technical scheme of the invention:
in the above step (5), the temperature is controlled to 60 ℃ to 70 ℃.
In the above step (7), the pH of the slurry is adjusted to 10.5 to 10.8.
And (4) adding hydrogen peroxide with the mass percentage concentration of 27.5 percent and the absolute dry pulp amount of 4.5 to 5.5 percent, sodium silicate with the absolute dry pulp amount of 3 to 6 percent and magnesium sulfate with the absolute dry pulp amount of 0.3 to 0.8 percent in the step (7).
The apocynum venetum pulp with the alpha fiber content of 93-93.5% is obtained by taking apocynum venetum branches as a raw material and performing optimized process treatment, a dipping procedure is omitted, and the apocynum venetum pulp is directly cooked, so that the process flow is reduced, the current situation that only apocynum venetum skin and apocynum venetum stalks are discarded in the prior art is changed, the plant waste is reduced, any purification reagent is not added in the preparation process, the COD (chemical oxygen demand) of the wastewater is 33000-40000 mg/L, the production cost is reduced, and the wastewater treatment difficulty is reduced.
Detailed Description
The present invention is not limited by the following examples, and specific embodiments may be determined according to the technical solutions and practical situations of the present invention. The various chemical reagents and chemical articles mentioned in the invention are all the chemical reagents and chemical articles which are well known and commonly used in the prior art, unless otherwise specified; the percentages in the invention are mass percentages unless otherwise specified; the normal temperature and room temperature in the present invention generally mean a temperature of 15 ℃ to 25 ℃, and are generally defined as 25 ℃.
The invention is further described below with reference to the following examples:
example 1: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 2: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting 3cm or 5cm long apocynum venetum branches;
(2) preparing alkali liquor: at normal temperature, adding 30 percent or 35 percent of sodium hydroxide relative to the absolute dry pulp, 10 percent or 12 percent of sodium sulfide relative to the absolute dry pulp and 2 percent or 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a cooker, heating at 120 deg.C or 130 deg.C under 0.3MPa or 0.35MPa for 25min or 30min, releasing steam for the first time at the end of the heating, at the end pressure of 0MPa or 0.05MPa for 8min or 12min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155 ℃ or 160 ℃, controlling the pressure at 0.55MPa or 0.65MPa and the time at 25min or 30min, after the temperature rise is finished, carrying out second steam release after heat preservation for 20min or 40min, controlling the end point pressure at the second steam release at 0.30MPa or 0.35MPa and the steam release time at 8min or 12min,
after the second time of steam release, carrying out third temperature rise, controlling the temperature at 155 ℃ or 160 ℃, controlling the pressure at 0.6MPa or 0.7MPa, controlling the time at 25min or 30min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90min or 100min, then carrying out third time of steam release, and controlling the end point pressure during the third time of steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30% or 35%, and reacting for 50min or 60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.35g/L or 0.65g/L, controlling the temperature to be 60 ℃ or 70 ℃, controlling the reaction time to be 55min or 65min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10% or 12% sodium hydroxide relative to the absolute dry pulp amount into a bleaching tank, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide to carry out primary bleaching at 80 ℃ or 90 ℃ for 80min or 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.35g/L or 0.45g/L, keeping the free alkali content at 85mg/L or 95mg/L, controlling the temperature at 43 ℃ or 47 ℃, bleaching for 95min or 105min, residual chlorine at 0.25g/L or 0.35g/L and residual alkali at 75mg/L or 80mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven-dry pulp amount of 0.1 percent or 0.15 percent and sodium hexametaphosphate with the relative oven-dry pulp amount of 0.3 percent or 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3g/L or 0.9g/L, and carrying out acid treatment for 55min or 65min at the temperature of 65 ℃ or 75 ℃;
(9) after the acid treatment is finished, washing, selecting and desanding, treating the washed apocynum pulp by a thickener until the pulp concentration is 3% or 5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
In the invention, sodium hydroxide, sodium sulfide, sodium dodecyl benzene sulfonate, hydrogen peroxide, oxalic acid, sodium hexametaphosphate, sodium hypochlorite, sodium silicate and magnesium sulfate are all commercial products. The oven-dried pulp refers to pulp with the fiber content of 100% and without any moisture, and the oven-dried pulp is one of the benchmarks for calculating the materials in the pulping and papermaking industries.
The apocynum venetum pulp with the alpha fiber content of 93-93.5% is obtained by taking the apocynum venetum branches as raw materials and performing optimized process treatment, so that the dipping process is omitted, the direct cooking is performed, and the process flow is reduced. The yield of the apocynum venetum pulp produced by using the apocynum venetum branches is 16-21%, the waste apocynum venetum stems are fully utilized, and the waste of raw materials is reduced.
In the present invention, the washing in step (4), the squeezing, the washing in step (9), the fine selection and the sand removal, and the papermaking are well known in the art, so the present invention is not described in detail.
In the invention, index detection is carried out after the step (4) is finished, the polymerization degree of the slurry is controlled to be 550-600, and the content of methyl cellulose is controlled to be 90-92%; after the step (5), index detection is carried out, the polymerization degree of the slurry is controlled to be 550-600, and the content of methyl cellulose is controlled to be 90-92%; and (4) after the step (8), index detection is carried out, the polymerization degree of the slurry is controlled to be 500-520, the whiteness is not less than 78%, and the content of methyl cellulose is 93-93.5%.
Example 3: as an optimization of the above embodiment, in the step (5), the temperature is controlled to be 60 ℃ to 70 ℃.
Example 4: as an optimization of the above example, in the step (7), the pH of the slurry is adjusted to 10.5 to 10.8.
Example 5: as optimization of the above embodiment, in the step (7), hydrogen peroxide with a mass percentage concentration of 27.5% and sodium silicate with a mass percentage concentration of 3% to 6% are added in an amount of 4.5% to 5.5% relative to the absolute dry pulp amount, and magnesium sulfate with a mass percentage of 0.3% to 0.8% relative to the absolute dry pulp amount.
Example 6: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting 3cm long apocynum venetum branches;
(2) preparing alkali liquor: at normal temperature, adding 30 percent of sodium hydroxide relative to the absolute dry pulp, 10 percent of sodium sulfide relative to the absolute dry pulp and 2 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 120 deg.C under 0.3MPa for 25min, releasing steam for the first time at 0MPa for 8min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155 ℃, the pressure at 0.55MPa and the time at 25min, after the temperature rise is finished, carrying out second steam release after heat preservation for 20min, controlling the end point pressure at 0.30MPa and the steam release time at 8min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155 ℃, the pressure at 0.6MPaa and the time at 25min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90min, then carrying out third steam release, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding 30 percent of sodium hydroxide relative to the absolute dry pulp, controlling the temperature at 60 ℃, and reacting for 50 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.35g/L, controlling the temperature to be 60 ℃, controlling the reaction time to be 55min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding 10 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp to be 10.5, then sequentially adding 3 percent of sodium silicate relative to the absolute dry pulp, 0.3 percent of magnesium sulfate relative to the absolute dry pulp and 27.5 percent of hydrogen peroxide by mass percent relative to 4.5 percent of the absolute dry pulp, carrying out primary bleaching at the primary bleaching temperature of 80 ℃ for 80min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.35g/L, free alkali at 85mg/L, controlling the temperature at 43 ℃, bleaching for 95min, residual chlorine at 0.25g/L and residual alkali at 75mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.1 percent of that of absolute dry pulp and sodium hexametaphosphate with the weight of 0.3 percent of that of absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3g/L, wherein the acid treatment time is 55min and the temperature is 65 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 7: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 35% of sodium hydroxide relative to the absolute dry pulp, 12% of sodium sulfide relative to the absolute dry pulp and 5% of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 130 deg.C under 0.35MPa for 30min, releasing steam for the first time at 0.05MPa for 12min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 160 ℃, the pressure at 0.65MPa and the time at 30min, after the temperature rise is finished, carrying out second steam release after heat preservation for 40min, controlling the end point pressure at 0.35MPa and the steam release time at 12min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 160 ℃, the pressure at 0.7MPa, controlling the time at 30min, carrying out heat preservation after the temperature rise is finished, carrying out third steam release after heat preservation is carried out for 100min, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding 35% sodium hydroxide relative to the absolute dry pulp, controlling the temperature at 70 ℃, and reacting for 60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.65g/L, controlling the temperature to be 70 ℃, controlling the reaction time to be 65min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding sodium hydroxide with the relative oven dry pulp amount of 12 percent into a bleaching pool, adjusting the pH value of the pulp to be 10.8, then sequentially adding sodium silicate with the relative oven dry pulp amount of 6 percent, magnesium sulfate with the relative oven dry pulp amount of 0.8 percent and hydrogen peroxide with the mass percent concentration of 27.5 percent and the relative oven dry pulp amount of 5.5 percent for primary bleaching, wherein the primary bleaching temperature is 90 ℃, the primary bleaching time is 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.45g/L, free alkali at 95mg/L, controlling the temperature at 47 ℃, bleaching for 105min, residual chlorine at 0.35g/L and residual alkali at 80mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.15 percent of that of absolute dry pulp and sodium hexametaphosphate with the weight of 0.5 percent of that of absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.9g/L, wherein the acid treatment time is 65min and the temperature is 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 8: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 4 cm;
(2) preparing alkali liquor: at normal temperature, adding sodium hydroxide with the weight of 32.5 percent of the absolute dry pulp, sodium sulfide with the weight of 11 percent of the absolute dry pulp and sodium dodecyl benzene sulfonate with the weight of 3 percent of the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 125 deg.C for 27.5min for the first time, releasing steam at 0.025MPa for 10min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 157.5 ℃, the pressure at 0.6MPa and the time at 27.5min, after the temperature rise is finished, carrying out second steam release after heat preservation for 30min, controlling the end point pressure at 0.33MPa and the steam release time at 10min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 157.5 ℃, the pressure at 0.65MPa and the time at 27.5min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 95min, then carrying out third steam release, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with a relative oven-dry pulp amount of 32.5%, controlling the temperature at 65 ℃, and reacting for 55 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.5g/L, controlling the temperature to be 65 ℃, controlling the reaction time to be 60min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding 11 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp to be 10.6, then sequentially adding 4.5 percent of sodium silicate relative to the absolute dry pulp, 0.55 percent of magnesium sulfate relative to the absolute dry pulp and 27.5 percent of hydrogen peroxide by mass percent relative to 5 percent of the absolute dry pulp for primary bleaching, wherein the primary bleaching temperature is 85 ℃, the primary bleaching time is 90min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.40g/L, free alkali at 90mg/L, controlling the temperature at 45 ℃, bleaching for 100min, residual chlorine at 0.3g/L and residual alkali at 77.5mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.13 percent of absolute dry pulp and sodium hexametaphosphate with the weight of 0.4 percent of absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.6g/L, wherein the acid treatment time is 60min and the temperature is 70 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 4%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 9: the preparation method of the apocynum venetum pulp for viscose fibers comprises the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 10: the apocynum venetum pulp for viscose fibers is obtained according to the following steps: the preparation method comprises the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 33.5 percent of sodium hydroxide relative to the absolute dry pulp, 10.9 percent of sodium sulfide relative to the absolute dry pulp and 2.6 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 120 deg.C under 0.3MPa for 25min, releasing steam for the first time at 0.05MPa for 10min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155 ℃, the pressure at 0.65MPa and the time at 25min, after the temperature rise is finished, carrying out second steam release after heat preservation for 30min, controlling the end point pressure at 0.30MPa and the steam release time at 10min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 160 ℃, the pressure at 0.68MPa, controlling the time at 25min, carrying out heat preservation after the temperature rise is finished, carrying out third steam release after the heat preservation is carried out for 100min, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with a relative oven-dry pulp amount of 32%, controlling the temperature at 70 ℃, and reacting for 60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.35g/L, controlling the temperature to be 65 ℃, controlling the reaction time to be 60min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding sodium hydroxide with the relative absolute dry pulp amount of 10.9 percent into a bleaching pool, adjusting the pH value of the pulp to be 10.8, then sequentially adding sodium silicate with the relative absolute dry pulp amount of 5 percent, magnesium sulfate with the relative absolute dry pulp amount of 0.5 percent and hydrogen peroxide with the mass percentage concentration of 27.5 percent with the relative absolute dry pulp amount of 5 percent for primary bleaching, wherein the primary bleaching temperature is 90 ℃, the primary bleaching time is 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.42g/L, free alkali at 93mg/L, controlling the temperature at 46 ℃, bleaching for 95min, residual chlorine at 0.35g/L and residual alkali at 80mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.1 percent of that of absolute dry pulp and sodium hexametaphosphate with the weight of 0.3 percent of that of absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3g/L, wherein the acid treatment time is 55min and the temperature is 70 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 4%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 11: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting 3.5cm long apocynum venetum branches;
(2) preparing alkali liquor: at normal temperature, adding 33.5 percent of sodium hydroxide relative to the absolute dry pulp, 10.5 percent of sodium sulfide relative to the absolute dry pulp and 2.6 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 120 deg.C under 0.31MPa for 25min, releasing steam for the first time at 0MPa for 10min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155 ℃, the pressure at 0.65MPa and the time at 25min, after the temperature rise is finished, carrying out second steam release after heat preservation for 30min, controlling the end point pressure at 0.35MPa and the steam release time at 10min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155 ℃, the pressure at 0.68MPa, controlling the time at 25min, carrying out heat preservation after the temperature rise is finished, carrying out third steam release after the heat preservation is carried out for 100min, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with a relative oven-dry pulp amount of 34.2%, controlling the temperature at 70 deg.C, and reacting for 60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.65g/L, controlling the temperature to be 70 ℃, controlling the reaction time to be 60min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding sodium hydroxide with the relative absolute dry pulp amount of 10.8 percent into a bleaching pool, adjusting the pH value of the pulp to be 10.6, then sequentially adding sodium silicate with the relative absolute dry pulp amount of 5 percent, magnesium sulfate with the relative absolute dry pulp amount of 0.5 percent and hydrogen peroxide with the mass percent concentration of 27.5 percent with the relative absolute dry pulp amount of 5 percent for primary bleaching, wherein the primary bleaching temperature is 90 ℃, the primary bleaching time is 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.45g/L, free alkali at 95mg/L, controlling the temperature at 46 ℃, bleaching for 95min, residual chlorine at 0.35g/L and residual alkali at 75mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.15 percent of the absolute dry pulp and sodium hexametaphosphate with the weight of 0.5 percent of the absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.5g/L, wherein the acid treatment time is 60min and the temperature is 70 ℃;
(9) after the acid treatment is finished, washing, selecting and desanding, treating the washed apocynum pulp by a thickener until the pulp concentration is 4.3%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
Example 12: the apocynum venetum pulp for viscose fibers is obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 4 cm;
(2) preparing alkali liquor: at normal temperature, adding 33.5 percent of sodium hydroxide relative to the absolute dry pulp, 11 percent of sodium sulfide relative to the absolute dry pulp and 2.7 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of herba Apocyni Veneti and prepared alkali solution into a digester, heating at 125 deg.C under 0.3MPa for 25min, releasing steam for the first time at 0MPa for 10min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155 ℃, the pressure at 0.6MPa and the time at 30min, after the temperature rise is finished, carrying out second steam release after heat preservation for 30min, controlling the end point pressure at 0.32MPa and the steam release time at 12min during the second steam release,
after the second steam release, carrying out third temperature rise, controlling the temperature at 158 ℃, the pressure at 0.66MPa and the time at 25min, carrying out heat preservation after the temperature rise is finished, carrying out third steam release after the heat preservation is carried out for 95min, and controlling the end point pressure during the third steam release at 0 MPa;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with a relative oven-dry pulp amount of 34.5%, controlling the temperature at 70 deg.C, and reacting for 55 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percent concentration of 37% to adjust the acid content of the slurry to be 0.5g/L, controlling the temperature to be 70 ℃, controlling the reaction time to be 55min, and entering a bleaching pool after pre-acid treatment;
(7) bleaching: adding sodium hydroxide with the relative absolute dry pulp amount of 10.8 percent into a bleaching pool, adjusting the pH value of the pulp to be 10.7, then sequentially adding sodium silicate with the relative absolute dry pulp amount of 5 percent, magnesium sulfate with the relative absolute dry pulp amount of 0.5 percent and hydrogen peroxide with the mass percentage concentration of 27.5 percent with the relative absolute dry pulp amount of 5 percent for primary bleaching, wherein the primary bleaching temperature is 90 ℃, the primary bleaching time is 90min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp at 0.39g/L, free alkali at 95mg/L, controlling the temperature at 47 ℃, bleaching for 95min, residual chlorine at 0.31g/L and residual alkali at 77mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the weight of 0.15 percent of that of absolute dry pulp and sodium hexametaphosphate with the weight of 0.3 percent of that of absolute dry pulp, and then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.5g/L, wherein the acid treatment time is 55min and the temperature is 70 ℃;
(9) after the acid treatment is finished, washing, selecting and desanding, treating the washed apocynum pulp by a thickener until the pulp concentration is 4.6%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
The results of the performance tests of the apocynum pulp for viscose fibres obtained in examples 10 to 12 are given in table 1. As can be seen from table 1, the apocynum venetum pulp for viscose obtained in example 10 has a whiteness of 80%, a polymerization degree of 489, a methyl cellulose content of 93.5%, a reactivity of 11mL 9s, an ash content of 0.16%, an iron content of 18mg/kg, and a soda absorption value of 530%; the apocynum venetum pulp for viscose obtained in example 11 has the whiteness of 79 percent, the polymerization degree of 520, the content of methyl cellulose of 93.2 percent, the reaction performance of 11mL 2s, the ash content of 0.19 percent, the iron content of 23mg/kg and the alkali absorption value of 530 percent; the apocynum pulp for viscose fiber obtained in example 12 has a whiteness of 78%, a polymerization degree of 517, a methyl cellulose content of 93.0%, a reactivity of 9mL 4s, an ash content of 0.22%, an iron content of 22mg/kg, and a soda absorption value of 521%.
As can be seen from the data in Table 1, the apocynum venetum pulp for viscose fibers obtained in examples 10 to 12 has the nail fiber content of 93 to 93.5 percent, the whiteness reaches over 78 percent, and reaches the standard in hemp pulp for viscose fibers FZ/T51009-2014, and the iron content is less than 0.25mg/kg, and reaches the standard in hemp pulp for viscose fibers FZ/T51009-2014.
In conclusion, the method changes the current situation that only apocynum venetum peels and apocynum venetum stalks are discarded in the prior art, reduces plant waste, does not add any purification reagent in the preparation process, and reduces the production cost and the treatment difficulty of the waste water because the COD of the waste water is 33000mg/L to 40000 mg/L.
The technical characteristics form an embodiment of the invention, which has strong adaptability and implementation effect, and unnecessary technical characteristics can be increased or decreased according to actual needs to meet the requirements of different situations.
TABLE 1
Claims (8)
1. An apocynum pulp used for viscose fiber is characterized by being obtained according to the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
2. The apocynum pulp for viscose according to claim 1, characterized in that in step (5), the temperature is controlled at 60 ℃ to 70 ℃.
3. The apocynum pulp for viscose according to claim 1 or 2, characterized in that in step (7), the pH of the pulp is adjusted to 10.5 to 10.8.
4. The apocynum venetum pulp for viscose according to claim 1 or 2 or 3, characterized in that in step (7), hydrogen peroxide with a concentration of 27.5% by mass in the range of 4.5% to 5.5% by weight of absolute dry pulp, sodium silicate in the range of 3% to 6% by weight of absolute dry pulp and magnesium sulfate in the range of 0.3% to 0.8% by weight of absolute dry pulp are added.
5. A preparation method of apocynum pulp used for viscose fiber is characterized by comprising the following steps:
(1) preparing materials: selecting apocynum venetum branches with the length of 3cm to 5 cm;
(2) preparing alkali liquor: at normal temperature, adding 30 to 35 percent of sodium hydroxide relative to the absolute dry pulp amount, 10 to 12 percent of sodium sulfide relative to the absolute dry pulp amount and 2 to 5 percent of sodium dodecyl benzene sulfonate relative to the absolute dry pulp amount to prepare alkali liquor;
(3) and (3) cooking: adding selected branch of Apocynum venetum and prepared alkali solution into a digester, heating at 120-130 deg.C under 0.3-0.35 MPa for 25-30 min, releasing steam for the first time after heating, releasing steam at 0-0.05 MPa for 8-12 min,
after the first steam release is finished, carrying out second temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.55-0.65 MPa and the time at 25-30 min, after the temperature rise is finished, keeping the temperature for 20-40 min, then carrying out second steam release, controlling the end point pressure at the second steam release at 0.30-0.35 MPa and the steam release time at 8-12 min,
after the second steam release, carrying out third temperature rise, controlling the temperature at 155-160 ℃, controlling the pressure at 0.6-0.7 MPa, controlling the time at 25-30 min, carrying out heat preservation after the temperature rise is finished, carrying out heat preservation for 90-100 min, then carrying out third steam release, and controlling the end point pressure at 0MPa during the third steam release;
(4) after cooking, washing and squeezing twice, and transferring into a pulping machine;
(5) alkali refining treatment: adding sodium hydroxide with the relative oven-dry pulp amount of 30-35% for reaction for 50-60 min;
(6) pre-acid treatment: adding hydrochloric acid with the mass percentage concentration of 37% to adjust the acid content of the slurry to be 0.35 g/L-0.65 g/L, controlling the temperature to be 60 ℃ to 70 ℃, controlling the reaction time to be 55 min-65 min, and sending the pre-acid treated slurry into a bleaching pool;
(7) bleaching: adding 10 to 12 percent of sodium hydroxide relative to the absolute dry pulp into a bleaching pool, adjusting the pH value of the pulp, then sequentially adding sodium silicate, magnesium sulfate and hydrogen peroxide for primary bleaching at the temperature of between 80 and 90 ℃ for 80 to 100min,
performing secondary bleaching, namely adding sodium hypochlorite with the effective chlorine content of 10 percent, keeping the effective chlorine content in the pulp to be 0.35-0.45 g/L, keeping the free alkali content in the pulp to be 85-95 mg/L, controlling the temperature to be 43-47 ℃, bleaching for 95-105 min, residual chlorine to be 0.25-0.35 g/L and residual alkali to be 75-80 mg/L, and performing acid treatment;
(8) acid treatment: adding oxalic acid with the relative oven dry pulp amount of 0.1 to 0.15 percent and sodium hexametaphosphate with the relative oven dry pulp amount of 0.3 to 0.5 percent, then adding hydrochloric acid with the mass percent concentration of 37 percent to adjust the acid content of the pulp to be 0.3 to 0.9g/L, and carrying out acid treatment for 55 to 65min at the temperature of 65 to 75 ℃;
(9) and after the acid treatment is finished, washing, selecting and removing sand, treating the washed apocynum pulp by a thickener until the pulp concentration is 3-5%, and then sending the pulp to a pulp machine for papermaking to obtain the apocynum pulp for viscose fibers.
6. The process for producing apocynum venetum pulp for viscose according to claim 5, wherein the temperature is controlled at 60 to 70 ℃ in the step (5).
7. The process for producing apocynum venetum pulp for viscose according to claim 5 or 6, characterized in that in the step (7), the pH of the pulp is adjusted to 10.5 to 10.8.
8. The method of claim 5 or 6 or 8, wherein the hydrogen peroxide solution with a concentration of 27.5% by mass is added in the step (7) in an amount of 4.5% to 5.5% by weight of the absolutely dry pulp, the sodium silicate is added in an amount of 3% to 6% by weight of the absolutely dry pulp, and the magnesium sulfate is added in an amount of 0.3% to 0.8% by weight of the absolutely dry pulp.
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