CN115746150A - Preparation method of high-purity nitrocotton - Google Patents
Preparation method of high-purity nitrocotton Download PDFInfo
- Publication number
- CN115746150A CN115746150A CN202211455407.4A CN202211455407A CN115746150A CN 115746150 A CN115746150 A CN 115746150A CN 202211455407 A CN202211455407 A CN 202211455407A CN 115746150 A CN115746150 A CN 115746150A
- Authority
- CN
- China
- Prior art keywords
- washing
- acid
- nitrocotton
- boiling
- cotton
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229920001220 nitrocellulos Polymers 0.000 title claims abstract description 124
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 238000005406 washing Methods 0.000 claims abstract description 122
- 239000002253 acid Substances 0.000 claims abstract description 97
- 238000009835 boiling Methods 0.000 claims abstract description 71
- 238000006396 nitration reaction Methods 0.000 claims abstract description 62
- 239000002994 raw material Substances 0.000 claims abstract description 38
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims abstract description 36
- 238000004519 manufacturing process Methods 0.000 claims abstract description 24
- 239000000126 substance Substances 0.000 claims abstract description 17
- 229920000742 Cotton Polymers 0.000 claims description 68
- 239000000047 product Substances 0.000 claims description 47
- 239000000463 material Substances 0.000 claims description 42
- 229920002678 cellulose Polymers 0.000 claims description 41
- 239000001913 cellulose Substances 0.000 claims description 41
- 238000000034 method Methods 0.000 claims description 39
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 38
- 238000006243 chemical reaction Methods 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 239000000020 Nitrocellulose Substances 0.000 claims description 27
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 19
- 238000010411 cooking Methods 0.000 claims description 18
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 17
- 229910017604 nitric acid Inorganic materials 0.000 claims description 17
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 14
- 230000007935 neutral effect Effects 0.000 claims description 12
- 238000002791 soaking Methods 0.000 claims description 8
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 7
- 239000012043 crude product Substances 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 239000003513 alkali Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- 239000002585 base Substances 0.000 description 7
- 238000005520 cutting process Methods 0.000 description 6
- 238000005886 esterification reaction Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000003380 propellant Substances 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 238000006073 displacement reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000032050 esterification Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 229910001037 White iron Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000009960 carding Methods 0.000 description 1
- 238000005352 clarification Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000010931 ester hydrolysis Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- -1 nitrocellulose ester Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007127 saponification reaction Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000000967 suction filtration Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- LENZDBCJOHFCAS-UHFFFAOYSA-N tris Chemical compound OCC(N)(CO)CO LENZDBCJOHFCAS-UHFFFAOYSA-N 0.000 description 1
Images
Landscapes
- Paper (AREA)
Abstract
The invention discloses a preparation method of high-purity nitrocotton, and belongs to the technical field of nitrocotton production. Aiming at the technical problem that the purity of the nitrocotton produced by the prior art is low, the invention provides a preparation method of the high-purity nitrocotton. According to the invention, the quality of raw materials in the production process of the nitrocotton is controlled, and the steps of nitration, acid removal, boiling and washing, fine breaking, fine washing and the like are combined and optimized, so that the high-purity nitrocotton with acetone insoluble substances and ash content lower than 0.1% can be obtained, the purity of the nitrocotton is greatly improved, and the quality of the nitrocotton is improved.
Description
Technical Field
The invention belongs to the technical field of nitrocotton production, and particularly relates to a preparation method of high-purity nitrocotton.
Background
Nitrocellulose (also known as Nitrocellulose, abbreviation NC) is the main component of mono-base, bi-base, tri-base, modified di-base, cross-linked modified di-base and composite modified di-base propellants. Wherein, the nitrocotton content in the single-base propellant is generally 94-97%, and the nitrocotton content in the (modified) double-base propellant is generally more than 50%.
The nitrocellulose is a product obtained by replacing hydroxyl in cellulose with nitrate, and the production process in the prior art mainly comprises the processes of cellulose pretreatment, nitration, acid removal, boiling and washing, fine breaking, fine washing and the like. After cellulose pretreatment, the cellulose is different from nitrated mixed acid (a mixture of nitric acid, sulfuric acid and water, the esterification capacities of different mixed acid components are different, at present, the nitrocotton is mainly classified into A, B, C, D cotton, and A, B, C, D cotton is mainly distinguished according to the fact that the nitrocotton is classified in intervals according to the nitrogen content of the nitrocotton, the nitrogen content of the nitrocotton is controlled to be mainly determined by the mixed acid components participating in the reaction and esterification conditions, the esterification reaction is completed in a reaction kettle, and the main process conditions in the esterification reaction process comprise nitration coefficient (mass ratio of the mixed acid participating in the reaction to the dry weight of the cellulose), reaction temperature and reaction time.
In the esterification reaction process, the nitric acid in the mixed acid is reduced, the moisture content is increased, the acid-cotton mixture after the reaction finishes acid driving and displacement washing in a centrifuge, the driven waste acid is recycled in an acid preparation machine, and the raw material nitric acid and sulfuric acid are supplemented to prepare the nitrated mixed acid for use; the amount of residual acid adsorbed by the material after the acid is removed from the nitrocotton (generally expressed in terms of residual acid) is still large, and replacement washing is also needed to reduce the absorption of residual acid by the nitrocotton.
And (4) stabilizing and adjusting the viscosity of the materials subjected to the flooding washing in a boiling washing kettle. In the prior art, the boiling and washing process is firstly carried out with acid boiling under certain acidity, temperature and time, and then is carried out with alkali boiling under certain alkalinity, temperature and time. After the alkaline boiling is finished, the material is subjected to fine breaking, fine washing and dehydration to obtain the energy-containing nitrocotton product. In order to ensure the stability of the nitro-cotton containing energy, a certain amount of sodium carbonate and calcium carbonate is added in the processes of fine breaking and fine washing, wherein the addition amount of the sodium carbonate and the calcium carbonate is about 2 per mill to 3 per mill of the absolute dry amount of the nitro-cotton.
The purity of the nitrocotton directly influences the purity of the subsequent propellant powder. The main technical indexes for measuring the purity of the nitrocotton are ash content and acetone insoluble substances, wherein the ash content index is that after the nitrocotton is subjected to nitrolysis and carbonization, the ignition residue is tested, and the components of the residue after ignition are mainly salt impurities; the acetone insoluble substance is a nitrogen content of less than 10.5%. As for the technical level of purity of the nitrocotton in China at present, the ash content is generally about 0.2%, and the content of acetone insoluble substances is generally about 0.25%.
Disclosure of Invention
The invention aims to solve the technical problem that the purity of the nitrocotton produced by the prior art is low.
In order to solve the technical problem, the invention provides a preparation method of high-purity nitrocotton, which comprises the following steps:
A. nitration reaction: mixing a cellulose raw material with mixed acid for nitration reaction to obtain a nitrocotton crude product; the cellulose raw material is refined cotton cellulose or pulp cellulose; the ash content of the cellulosic feedstock is no more than 0.15wt%; the content of nitrocellulose in the mixed acid is not more than 0.3wt%;
wherein, when refined cotton cellulose is used as a raw material, the content of nitric acid in the mixed acid is controlled to be 21-23 wt%; controlling the nitration coefficient to be 40-60; controlling the time of nitration reaction to be 30-35 min; the reaction temperature of the target product B cotton is 27-30 ℃; the reaction temperature of the target product A, C or D cotton is 32-35 ℃;
when pulp cellulose is used as a raw material, controlling the nitric acid content in the mixed acid to be 45.5-49 wt%; controlling the nitration coefficient to be 18-25; the time of nitration reaction is 60-80 min; the reaction temperature of the target product B cotton is 40-45 ℃; the reaction temperature of the target product A, C or D cotton is 47-52 ℃;
B. acid-driving washing: b, performing acid-flooding washing on the crude product obtained in the step A, and controlling the residual acidity of the material subjected to the acid-flooding washing to be lower than 20%;
C. boiling and washing: acid cooking: acid boiling is carried out on the material subjected to acid-flooding washing, and the initial acidity of the boiling washing water is controlled: 2-6 g/L, the acid cooking time of the target product B cotton is not less than 6h, and the acid cooking time of the target product A, C or D cotton is not less than 4h;
boiling in water: boiling the acid-boiled material in water, controlling the initial pH of the boiling and washing water to be neutral, wherein the boiling time of the target product B cotton is not less than 6h, and the boiling time of the target product A, C or D cotton is not less than 4h;
soaking and hot washing: soaking and hot washing the boiled materials by using 0.2-0.5 g/L sodium carbonate aqueous solution at the hot washing temperature of 50-70 ℃;
D. finely cutting and finely washing: sodium carbonate with the dry weight of 0.5 to 1.0 per mill of the nitrocotton is added in the fine breaking process, and sodium carbonate with the dry weight of 0 to 1.0 per mill of the nitrocotton is added in the fine washing process;
E. after fine washing, dewatering to obtain the high-purity nitrocotton.
Preferably, in the method for preparing high-purity nitrocellulose, in the step a, the ash content of the cellulose raw material is not more than 0.12wt%.
Preferably, in the method for preparing high-purity nitrocellulose, in the step a, the nitrocellulose content in the mixed acid is not more than 0.2wt%.
Preferably, in the method for preparing high-purity nitrocellulose, in the step a, when refined cotton cellulose is used as a raw material, the nitration coefficient is controlled to be 48 to 52; the time of the nitration reaction is controlled to be 32-33 min.
Preferably, in the method for preparing the high-purity nitrocotton, in the step A, when pulp cellulose is used as a raw material, the nitration coefficient is controlled to be 19-22; the time of nitration reaction is 65-75 min.
Preferably, in the method for preparing high-purity nitrocotton, in the step B, the residual acid content of the material after the acid-driving washing is controlled to be lower than 15%.
Preferably, in the method for preparing high-purity nitrocotton, in the step C, when acid boiling is performed, the initial acidity of the boiling and washing water is controlled: 3-6 g/L.
Wherein, in the step C, the acid boiling temperature is controlled to be less than 120 ℃ during acid boiling.
In the preparation method of the high-purity nitrocotton, in the step C, the washing time after acid boiling is based on the pH value of the washed material as neutral.
Wherein, in the step C, the boiling temperature is controlled to be less than 120 ℃ when the high-purity nitrocotton is boiled.
In the preparation method of the high-purity nitrocotton, in the step C, the washing time after water boiling is based on the pH value of the washed material being neutral.
In the preparation method of the high-purity nitrocotton, in the step C, the hot washing time is controlled to be 1-2 h when the nitrocotton is soaked and hot washed.
In the preparation method of the high-purity nitrocotton, calcium carbonate is not added in the processes of fine breaking and fine washing in the step D.
In the preparation method of the high-purity nitrocotton, the content of acetone insoluble substances and ash content of the high-purity nitrocotton are not more than 0.1wt%.
In the invention, the nitration coefficient refers to the mass ratio of the dry weight of the cellulose raw material to the mixed acid in the nitration process.
In the invention, the residual acidity is the mass ratio of the residual acidity (calculated by sulfuric acid) in the material after the acid-flooding washing to the dry weight of the nitrocotton.
The invention has the beneficial effects that:
the method deeply researches relevant factors influencing the purity of the nitrocotton in the production of the nitrocotton, controls the quality of raw materials in the production process of the nitrocotton, combines the steps of optimizing nitrification, acid removal, boiling and washing, fine breaking, fine washing and the like, can obtain the high-purity nitrocotton with acetone insoluble substances and ash content lower than 0.1 percent, greatly improves the purity of the nitrocotton, and improves the quality of the nitrocotton.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
Specifically, the preparation method of the high-purity nitrocotton comprises the following steps:
A. nitration reaction: mixing a cellulose raw material with mixed acid for nitration reaction to obtain a crude product of nitrocotton; the cellulose raw material is refined cotton cellulose or pulp cellulose; the ash content of the cellulosic feedstock is no more than 0.15wt%; the content of the nitrocellulose in the mixed acid is not more than 0.3wt%;
wherein, when refined cotton cellulose is used as a raw material, the content of nitric acid in the mixed acid is controlled to be 21-23 wt%; controlling the nitration coefficient to be 40-60; controlling the time of nitration reaction to be 30-35 min; the reaction temperature of the target product B cotton is 27-30 ℃; the reaction temperature of the target product A, C or D cotton is 32-35 ℃;
when pulp cellulose is used as a raw material, controlling the nitric acid content in the mixed acid to be 45.5-49 wt%; controlling the nitration coefficient to be 18-25; the time of nitration reaction is 60-80 min; the reaction temperature of the target product B cotton is 40-45 ℃; the reaction temperature of the target product A, C or D cotton is 47-52 ℃;
B. acid-driving washing: b, performing acid-flooding washing on the crude product obtained in the step A, and controlling the residual acidity of the material subjected to the acid-flooding washing to be lower than 20%;
C. boiling and washing: acid cooking: acid boiling is carried out on the material subjected to acid-flooding washing, and the initial acidity of the boiling washing water is controlled: 2-6 g/L, the acid cooking time of the target product B cotton is not less than 6h, and the acid cooking time of the target product A, C or D cotton is not less than 4h;
boiling in water: boiling the acid-boiled material in water, controlling the initial pH of the boiling and washing water to be neutral, wherein the boiling time of the target product B cotton is not less than 6h, and the boiling time of the target product A, C or D cotton is not less than 4h;
soaking and hot washing: soaking and hot washing the boiled materials by using 0.2-0.5 g/L sodium carbonate aqueous solution at the hot washing temperature of 50-70 ℃;
D. finely cutting and finely washing: sodium carbonate with the dry weight of 0.5-1.0 per mill of the nitrocotton is added in the fine breaking process, and sodium carbonate with the dry weight of 0-1.0 per mill of the nitrocotton is added in the fine washing process;
E. after fine washing, dewatering to obtain the high-purity nitrocotton.
In the production of nitrocotton, the ash content of raw materials, and the amount of inorganic salt added in boiling, washing, fine breaking and fine washing all influence the ash content of nitrocotton; in the production process, the acetone insoluble substance content of the nitrocotton can be influenced by the processes of nitration, acid removal, boiling and washing and the like. Therefore, the invention optimizes the quality of raw materials in the nitrocotton production process, and the steps of nitration, acid removal, boiling and washing, fine breaking, fine washing and the like, and comprehensively adjusts various factors to obtain the high-purity nitrocotton.
In the art, the cellulose raw material for producing nitrocellulose is generally refined cotton cellulose or pulp cellulose, which requires pretreatment and then nitration reaction. When refined cotton cellulose is used as a raw material, a carding machine or a cotton grabbing machine is generally adopted to untwist the packed refined cotton into fluffy flocculent refined cotton, and when pulp cellulose is used as a raw material, a slicer is generally adopted to cut a pulp roll into granular pulp with a certain specification. In addition, the refined cotton is long and fluffy, so that the refined cotton can be soaked by the mixed acid and keep the fluidity by using a larger amount of the mixed acid; and the sliced pulp is granular, so that the material can be ensured to be soaked by the mixed acid and keep the fluidity by only needing a small amount of the mixed acid.
The ash content of the cellulose raw material directly influences the ash content of the nitrocotton, so the invention controls the ash content of the purified cotton and the pulp raw material. Tests show that the content of the cellulose raw material is required to be controlled to be not more than 0.15 percent, and more preferably not more than 0.12 percent.
The nitration reaction process of cellulose and mixed acid is key for determining the content of acetone insoluble substances in the nitro-cotton, and the main nitration conditions of the high-purity nitro-cotton with low content of the acetone insoluble substances are as follows:
(1) And the cleanliness requirement of the mixed acid for nitration is as follows: in the production process of the nitrocotton, the mixed acid is prepared by using waste acid after acid displacement as mother liquor acid, and then raw materials of nitric acid and sulfuric acid are supplemented to prepare a ternary mixture of nitric acid, sulfuric acid and water, namely the mixed acid for nitration. In the prior art, the cleanness degree of mixed acid is not emphasized. However, a large number of experiments show that some fine nitrocotton cannot be brought into waste acid in the acid-expelling process, the part of the nitrocotton stays in acid for too long time, irregular reactions such as denitration and re-nitration exist, and the acetone insoluble substance brought into the product not only has the product quality, but also can greatly influence the rise of the acetone insoluble substance of the product. The mixed acid adopted by the invention can be prepared by adopting the prior art, but in order to reduce the content of acetone insoluble substances in the nitrocotton product, the content of nitrocotton fibers in the selected mixed acid for nitration needs to be controlled to be not more than 0.3 percent, and preferably not more than 0.2 percent. The invention can realize the purification of the mixed acid by natural clarification or filtration treatment, and the like, thereby preparing the high-purity nitrocotton.
(2) And main nitration conditions: in industrial production, the nitration reaction is generally operated as follows: a certain amount of cellulose is soaked by a certain amount of mixed acid and then enters a reactor together, and a certain reaction time and reaction temperature are controlled in the reaction process. However, in the prior art, the condition control of the nitration reaction is extensive, and the production requirement of the high-purity nitrocotton is difficult to meet. Specifically, the method comprises the following steps:
in the prior art, the reaction mixed acid taking refined cotton as a raw material is generally controlled according to the nitric acid content of 18-25 percent, but the range can not meet the reaction requirement of high-purity nitrocotton, and simultaneously, the nitric acid content is too high, the process volatilization is large, and the cost is increased; in the prior art, the reaction temperature of the B cotton is generally 20-30 ℃, the reaction temperature of the A, C, D cotton is generally 30-40 ℃, and the reaction temperature can not meet the reaction requirement of high-purity nitrocotton. The inventor determines through a large number of experiments that on the premise of meeting the nitration quality of high-purity nitrocotton, the content of nitric acid in the mixed acid is controlled to be 21-23%, the reaction temperature of cotton B is 27-30 ℃, and the reaction temperature of A, C, D is 32-35 ℃.
The nitration coefficient and the nitration time also influence the purity of the nitro-cotton, when the refined cotton cellulose is used as a raw material, the nitration coefficient needs to be controlled to be 40-60 and the nitration reaction time is 30-35 min through tests; preferably, the nitration coefficient is controlled to be 48-52, and the time of nitration reaction is controlled to be 32-33 min.
In the prior art, the reaction mixed acid taking pulp as a raw material is generally controlled according to 45-50% of nitric acid content, but the range can not meet the reaction requirement of high-purity nitrocotton, and simultaneously, the nitric acid content is too high, the process volatilization is large, and the cost is increased; in the prior art, the reaction temperature of the B cotton is generally 35-45 ℃, the reaction temperature of the A, C, D cotton is generally 45-55 ℃, and the reaction temperature can not meet the reaction requirement of high-purity nitrocotton. The inventor determines through a large number of experiments that on the premise of meeting the nitration quality of high-purity nitrocotton, the nitric acid content in the mixed acid is controlled to be 45.5-49 wt%, the reaction temperature of the cotton B is 40-45 ℃, and the reaction temperature of the A, C, D cotton is 47-52 ℃.
The nitration coefficient and the nitration time also influence the purity of the nitrocotton, and when pulp cellulose is used as a raw material, the nitration coefficient needs to be controlled to be 18-25 and the nitration reaction time is 60-80 min through tests; preferably, the nitration coefficient is controlled to be 19-22, and the time of nitration reaction is 65-75 min.
The acid cotton mixture after nitration is generally subjected to acid-driving and displacement washing in a centrifuge. The requirement of acid drive washing is as follows: the nitrocotton acid-flooding washing effect is also a main factor influencing the purity of the nitrocotton, the acid-flooding washing effect is good, the quantity of the material carrying residual acid is small, the subsequent stable treatment is facilitated, the acid-flooding washing effect is poor, the quantity of the material carrying residual acid is large, the subsequent stable treatment is difficult, in order to ensure the final stability of the product, the subsequent fine washing not only needs hot washing to increase energy consumption, but also needs to increase the sodium carbonate dosage to neutralize the material residual acid, and the ash content of the product is increased. The step B of the invention can be operated by adopting the existing flooding washing process, but the residual acidity of the material after flooding washing needs to be strictly controlled to be lower than 20 percent, and is better if the residual acidity is lower than 15 percent, so that the subsequent stable treatment is facilitated; if the residual acidity is too high, the stability qualification rate of the product after subsequent stabilization treatment is low.
In the nitrocotton process in the prior art, the processes of acid boiling and alkali boiling (the alkali boiling temperature is generally above 100 ℃ and the alkali boiling time is long) are adopted for boiling and washing, and in the alkali boiling process, a certain degree of saponification reaction of the nitrocellulose ester exists, which can cause the insoluble content of acetone in the nitrocotton product to be increased.
The acid cooking process conditions are as follows: controlling the initial acidity of the boiling and washing water: 2 to 6g/L, preferably 3 to 6g/L; according to different target products, proper acid boiling time needs to be controlled so as to be beneficial to releasing unstable impurities of low-grade and low-nitrogen nitrates in fiber channels, reduce the content of acetone insoluble substances in the product and ensure that the stability meets the requirements: the acid cooking time of cotton B is not less than 6h, and the acid cooking time of cotton A and C, D is not less than 4h; the acid cooking temperature is less than 120 ℃ (the specific temperature can be adjusted according to the viscosity of the product); and (4) performing conventional washing after acid cooking, wherein the washing time is based on that the pH of the washed material is neutral.
The water boiling process conditions are as follows: controlling the initial pH value of the boiling and washing water to be neutral (if the initial pH value is written to be neutral, the initial pH value is generally 7 by default, the protection range is too small, and a supplement range is recommended); according to different target products, the proper acid cooking time is controlled as well: the cotton water boiling time of B is not less than 6h, and the cotton water boiling time of A, C, D is not less than 4h; the boiling temperature is less than 120 ℃ (the specific temperature can be adjusted according to the viscosity of the product); and (4) performing conventional washing after water boiling, wherein the washing time is based on that the pH of the washed materials is neutral.
The rigidity of the nitrocellulose which is not boiled by alkali is poor, the nitrocellulose is not beneficial to fine breaking, and in order to ensure the fine breaking degree, the fine breaking process needs to consume longer time and energy consumption; most of the fine breaking equipment grinding plates are made of alloy steel or white cast iron, and the nitrocotton fibers carry residual acid to be corroded by the grinding plates. Therefore, although the invention is subjected to 'acid boiling + water boiling', the material system can not be directly broken, and meanwhile, because the invention is subjected to 'acid boiling + water boiling', a low-strength alkali washing mode is adopted, the material entrained residual acid can be further neutralized, the product stability is improved, and ester hydrolysis in the alkali washing process can be avoided. Tests show that under the conditions of improving the fine breaking efficiency and preventing the residual acid of the material from corroding the grinding disc or the fine breaking equipment, the material is soaked and hot-washed by using 0.2-0.5 g/L sodium carbonate aqueous solution after being boiled and washed, the hot-washing temperature is controlled to be 50-70 ℃, and the hot-washing time is 1-2 hours.
In the prior art, certain amount of calcium carbonate is added in the processes of fine breaking and fine washing of the nitrocellulose manufacturing process, which is beneficial to the stability of products, but the content of ash and acetone insoluble substances of the products is increased, so that the nitrocellulose products with low ash content and low acetone insoluble substances are difficult to obtain. The invention ensures the stability of the product without adding calcium carbonate by improving the front-end acid-driving washing, boiling washing and alkali washing processes. Therefore, in the method, no calcium carbonate is added in the fine breaking and fine washing processes, the amount of sodium carbonate added in the fine breaking process is 0.5-1.0 per mill of the absolute dry weight of the nitrocotton, and the amount of sodium carbonate added in the fine washing process is 0-1.0 per mill of the absolute dry weight of the nitrocotton (according to the stability condition of the nitrocotton).
In addition, in most of the existing nitrocellulose manufacturing processes, the slurry after being thinned is directly sent to a fine washing machine; the invention adds a suction filtration washing process after fine breaking, and separates unstable impurities in the fine breaking material once again, thereby further ensuring that the stability of the final product meets the requirement. The method comprises the following specific steps: after soaking and hot washing, discharging directly without draining water, finely cutting, adding sodium carbonate with the dry weight of the nitrocotton of 0.5-1.0 per mill in the finely cutting process, dehydrating the slurry after finely cutting until the water content of the material is lower than 70wt%, finely washing the dehydrated material with the pulp regulating concentration of 8-12 wt%, and adding the sodium carbonate with the amount of 0-1.0 per mill of the absolute dry weight of the nitrocotton in the finely washing process.
In the industrial production of the nitrocotton, when each batch of raw materials is nitrified, the feeding quantity of the purified cotton is controlled for controlling the quantity of the nitrocotton of each batch, and the actual yield is clearer according to the esterification substitution reaction and the actual experience, so the nitrocotton can be calculated and metered in the actual production.
The method integrates the influence of the above total factors, optimizes the quality of raw materials in the production process of the nitrocotton, and optimizes the steps of nitration, acid removal, boiling and washing, fine breaking, fine washing and the like, obviously improves the purity of the obtained nitrocotton product, and ensures that the content of acetone insoluble substances and ash content are not more than 0.1wt%.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
Taking X60 refined cotton, X60 wood pulp and X200 cotton pulp as raw materials, pretreating, and carrying out nitration reaction according to nitration parameters shown in table 1 to obtain crude products of A-D cotton.
TABLE 1 nitration parameters
And (3) performing acid-flooding washing on the crude cotton products A to D by adopting a five-section countercurrent washing process, and controlling the residual acidity of the materials after the acid-flooding washing according to the table 2.
TABLE 2 residual acidity after acid-flooding washing
| Serial number | Variety of (IV) C | Degree of residual acidity after acid-driving washing% |
| 1 | A | 13.6 |
| 2 | B | 10.7 |
| 3 | C | 14.2 |
| 4 | D | 15.8 |
| 5 | B | 12.9 |
| 6 | D | 8.7 |
| 7 | B | 7.2 |
| 8 | D | 11.5 |
Performing acid boiling, water boiling and hot washing on the material subjected to the acid-driving washing in sequence according to the boiling and washing process conditions in the table 3, and performing conventional washing on the acid-boiled material and the water-boiled material, wherein the washing end point is determined by taking the pH test paper as a neutral point; after water boiling and washing, the mixture is washed by low-concentration alkaline water in a hot mode, water is not discharged after the hot washing is finished, and the mixture is directly discharged to subsequent fine cutting.
TABLE 3 Wash Process conditions
And (2) performing fine breaking and fine washing according to the process conditions in the table 4, dehydrating the slurry after the fine breaking by using a vacuum belt type suction filter until the water content of the material is lower than 70%, fine washing the dehydrated material with the pulp adjusting concentration of 8-12%, controlling the addition amount of sodium carbonate in the fine breaking and fine washing processes, stirring the slurry after the fine breaking of various nitrocottons for 30min at normal temperature in the fine washing machine without further hot washing, and dehydrating after the fine washing to obtain finished products of the cotton A-D, wherein the quality technical indexes are shown in the table 5.
TABLE 4 addition of finely divided, finely washed sodium carbonate
TABLE 5 quality technical indexes of various nitrocottons
Claims (10)
1. The preparation method of the high-purity nitrocotton is characterized by comprising the following steps: the method comprises the following steps:
A. nitration reaction: mixing a cellulose raw material with mixed acid for nitration reaction to obtain a crude product of nitrocotton; the cellulose raw material is refined cotton cellulose or pulp cellulose; the ash content of the cellulosic feedstock is no more than 0.15wt%; the content of the nitrocellulose in the mixed acid is not more than 0.3wt%;
wherein, when refined cotton cellulose is used as a raw material, the content of nitric acid in the mixed acid is controlled to be 21-23 wt%; controlling the nitration coefficient to be 40-60; controlling the time of the nitration reaction to be 30-35 min; the reaction temperature of the target product B cotton is 27-30 ℃; the reaction temperature of the target product A, C or D cotton is 32-35 ℃;
when pulp cellulose is used as a raw material, controlling the nitric acid content in the mixed acid to be 45.5-49 wt%; controlling the nitration coefficient to be 18-25; the time of nitration reaction is 60-80 min; the reaction temperature of the target product B cotton is 40-45 ℃; the reaction temperature of the target product A, C or D cotton is 47-52 ℃;
B. acid-driving washing: b, performing acid-flooding washing on the crude product obtained in the step A, and controlling the residual acidity of the material subjected to the acid-flooding washing to be lower than 20%;
C. boiling and washing: acid cooking: acid boiling is carried out on the material subjected to acid-flooding washing, and the initial acidity of the boiling washing water is controlled: 2-6 g/L, the acid cooking time of the target product B cotton is not less than 6h, and the acid cooking time of the target product A, C or D cotton is not less than 4h;
boiling in water: boiling the acid-boiled material in water, controlling the initial pH of the boiling and washing water to be neutral, wherein the boiling time of the target product B cotton is not less than 6h, and the boiling time of the target product A, C or D cotton is not less than 4h;
soaking and hot washing: soaking and hot washing the boiled materials by using 0.2-0.5 g/L sodium carbonate aqueous solution at the hot washing temperature of 50-70 ℃;
D. fine breaking and fine washing: sodium carbonate with the dry weight of 0.5 to 1.0 per mill of the nitrocotton is added in the fine breaking process, and sodium carbonate with the dry weight of 0 to 1.0 per mill of the nitrocotton is added in the fine washing process;
E. after fine washing, dewatering to obtain the high-purity nitrocotton.
2. The method for producing high purity nitrocellulose according to claim 1, wherein: in the step A, the ash content of the cellulose raw material is not more than 0.12wt%; the content of the nitrocellulose in the mixed acid is not more than 0.2wt%.
3. The method for producing high purity nitrocellulose according to claim 1, wherein: in the step A, when refined cotton cellulose is used as a raw material, controlling the nitration coefficient to be 48-52; the time of the nitration reaction is controlled to be 32-33 min.
4. The method for producing high purity nitrocellulose according to claim 1, wherein: in the step A, when pulp cellulose is used as a raw material, the nitration coefficient is controlled to be 19-22; the time of nitration reaction is 65-75 min.
5. The method for producing high purity nitrocellulose according to claim 1, wherein: and in the step B, controlling the residual acidity of the material subjected to the acid-driving washing to be lower than 15%.
6. The method for producing high purity nitrocellulose according to claim 1, wherein: in step C, at least one of the following is satisfied:
when acid boiling, controlling the initial acidity of the boiling and washing water: 3-6 g/L;
when in acid cooking, the acid cooking temperature is controlled to be less than 120 ℃;
the washing time after acid cooking is based on the pH value of the washed materials as neutral.
7. The method for producing high purity nitrocellulose according to claim 1, wherein: in step C, at least one of the following is satisfied:
when boiling, controlling the boiling temperature to be less than 120 ℃;
the washing time after water boiling is based on the pH value of the washed materials as neutral.
8. The method for producing high purity nitrocellulose according to claim 1, wherein: and C, controlling the hot washing time to be 1-2 h when soaking and hot washing.
9. The method for producing high purity nitrocellulose according to claim 1, wherein: in the step D, calcium carbonate is not added in the processes of fine breaking and fine washing.
10. The method for producing high purity nitrocellulose according to any one of claims 1 to 9, wherein: the content of acetone insoluble substances and ash content of the high-purity nitrocotton are not more than 0.1wt%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211455407.4A CN115746150B (en) | 2022-11-21 | 2022-11-21 | High purity nitrocotton preparation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211455407.4A CN115746150B (en) | 2022-11-21 | 2022-11-21 | High purity nitrocotton preparation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115746150A true CN115746150A (en) | 2023-03-07 |
| CN115746150B CN115746150B (en) | 2024-03-19 |
Family
ID=85333486
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211455407.4A Active CN115746150B (en) | 2022-11-21 | 2022-11-21 | High purity nitrocotton preparation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115746150B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116621996A (en) * | 2023-04-27 | 2023-08-22 | 北方化学工业股份有限公司 | Industrial nitrocotton stability treatment method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102321183A (en) * | 2011-08-05 | 2012-01-18 | 四川北方硝化棉股份有限公司 | Wood pulp nitrocotton production method |
| CN112321726A (en) * | 2020-11-23 | 2021-02-05 | 北方化学工业股份有限公司 | Boiling and washing process of low-viscosity high-nitration-degree energy-containing B cotton |
| CN112409497A (en) * | 2020-11-09 | 2021-02-26 | 北方化学工业股份有限公司 | Preparation method of low-ash energy-containing nitrocotton |
-
2022
- 2022-11-21 CN CN202211455407.4A patent/CN115746150B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102321183A (en) * | 2011-08-05 | 2012-01-18 | 四川北方硝化棉股份有限公司 | Wood pulp nitrocotton production method |
| CN112409497A (en) * | 2020-11-09 | 2021-02-26 | 北方化学工业股份有限公司 | Preparation method of low-ash energy-containing nitrocotton |
| CN112321726A (en) * | 2020-11-23 | 2021-02-05 | 北方化学工业股份有限公司 | Boiling and washing process of low-viscosity high-nitration-degree energy-containing B cotton |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116621996A (en) * | 2023-04-27 | 2023-08-22 | 北方化学工业股份有限公司 | Industrial nitrocotton stability treatment method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115746150B (en) | 2024-03-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104114615B (en) | A kind of method preparing lignin component, lignin component and application thereof and product | |
| CN115746150A (en) | Preparation method of high-purity nitrocotton | |
| DE2027319B2 (en) | Process for the production of chemically readily soluble cellulose | |
| US4439605A (en) | Process for producing cellulose acetate | |
| EP1707668A1 (en) | Closed cycle zero discharge oxidizing pulping process | |
| GB1569138A (en) | Production of monosaccharides and a cellulosicrich material from straw | |
| CN116333173A (en) | Cellulose acetate and preparation method thereof | |
| CN112409497A (en) | Preparation method of low-ash energy-containing nitrocotton | |
| CN102219861B (en) | Method for preparing cellulose nitrate for explosive from wood pulp | |
| US1891337A (en) | Process of producing cellulose | |
| CN1044480C (en) | Process for producing cellulose acetate | |
| US2625474A (en) | Acid-alkali process for the preparation of cellulose fibers | |
| CN112064137B (en) | Preparation method of polyamide 6 and melt direct-spun fiber of polyamide 6 graphene modified substance | |
| CN112796150A (en) | Preparation method of paper pulp fiber | |
| US4350671A (en) | Method of preparing phosphoric acid by a wet process | |
| CN115504440B (en) | Double-circulation wet-process phosphoric acid production method | |
| CN115028745A (en) | Energy-containing nitrocotton and preparation method thereof | |
| CN114409523B (en) | Preparation method of 1, 3-acetone dicarboxylic acid | |
| RU2740098C1 (en) | Method for hydrolysis of hemicelluloses of plant materials for producing xylose solutions | |
| CN118026116B (en) | Method for preparing diammonium phosphate from monoammonium phosphate mother liquor | |
| EP0114162B1 (en) | Process for the treatment of starch or raw materials containing starch | |
| DE730317C (en) | Process for the production of sulphite pulp | |
| CN115403490B (en) | Refining method of sodium methallyl sulfonate | |
| SU573524A1 (en) | Method of obtaining cotton cellulose | |
| CN117779167A (en) | Method for preparing calcium sulfate whisker by taking ferric phosphate mother liquor as raw material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |