Corncob nitrocellulose as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of plant fiber recycling, and particularly relates to corncob nitrocellulose as well as a preparation method and application thereof. The preparation method comprises the following steps: performing alkalization treatment on corncob powder to form corncob powder easy to hydrolyze, and removing hemicellulose and lignin; neutralizing and acidizing to remove impurities such as grease and the like; carrying out nitration treatment on the acidified corncob powder to form a corncob fiber rubber powder semi-finished product; reacting potassium nitrate, diphenylamine and the preheated corncob fiber rubber powder semi-finished product under a heating condition, and adding a stabilizer to form corncob fiber rubber powder, namely the corncob nitrocellulose. The corncob fiber rubber powder is excellent in combustion performance, free of smoke and peculiar smell, only has trace residues after combustion, can be used as various safe and environment-friendly firework products, and can also be used as an environment-friendly coating additive material.

Description

Technical Field

[0001] The invention belongs to the technical field of plant fiber regeneration and utilization, and specifically relates to nitrocellulose and a preparation method and application thereof. Background Art

[0002] With the environmental protection requirements and the development of fireworks and firecrackers towards high-performance, environmentally friendly and safe types, the products are developing towards indoor and smokeless forms, and single-base gunpowder is usually used as the main raw material. Although single-base gunpowder can reduce a large amount of smoke in fireworks products, it is a controlled material with limited supply and high price, which cannot meet the needs of fireworks and firecrackers production. In addition, single-base gunpowder has low sensitivity and contains a small amount of nitroglycerin, which is very prone to safety accidents such as explosions, and is very unsafe during production and transportation.

[0003] Nitrocellulose, the main component of single-base gunpowder, is an important material in the fields of fireworks, paints, plastics, papermaking, and pharmaceuticals. It is usually prepared from cotton. Due to the limitations of raw material resources, prices, and management, people continue to explore other ways to prepare nitrocellulose.

[0004] At present, the fireworks industry has begun to use plants to prepare research and application of cellulose powder for fireworks. However, due to the limitations of production conditions, the preparation process of cellulose powder for fireworks is that in the existing industry production process, the plant raw materials are crushed and then subjected to simple chemical treatment, and the mixture is directly added to the reactor for nitration treatment. During the reaction process, the mixture added to the reactor contains more impurities and the acid and alkali dosage is not uniform, resulting in waste of raw materials and the release of a large amount of wastewater and exhaust gas, causing serious environmental pollution. In addition, the products produced thereby contain a large amount of impurities, resulting in poor combustion performance of the products and releasing more smoke during combustion, which not only wastes raw materials but also pollutes the environment.

[0005] Therefore, it is necessary to provide a novel nitrocellulose production process using plants as raw materials to solve the above problems.

[0006] The present invention uses corn cobs, which are waste from corn crops, as the main raw material. Corn is mainly distributed in tropical, subtropical and warm regions, and a portion of it can be used as food, vegetables, feed or industrial materials, but its corn cobs are mainly burned, which often produces a lot of smoke and causes serious pollution to the natural environment. The present invention recycles corn cobs as the main material, solves the problem of environmental pollution, and turns waste into treasure. Summary of the invention

[0007] The purpose of the present invention is to provide a nitrocellulose made from corn cobs which has good combustion performance and can avoid releasing a lot of smoke, and a preparation method and use thereof, so as to realize the waste utilization of corn cobs and prepare corn cob nitrocellulose which has strong stability, good environmental protection, is smokeless, has no odor and only produces a trace amount of residue after combustion.

[0008] The present invention provides a method for preparing nitrocellulose using corn cob as raw material (hereinafter referred to as corn cob nitrocellulose), and the specific steps are as follows.

[0009] (1) Alkalization treatment: that is, the corn cob powder is subjected to alkalization treatment to form easily hydrolyzed corn cob powder, and hemicellulose and lignin are removed; wherein:

[0010] The fineness of the corn cob powder is 60-80 mesh; the alkalizing agent for the alkalization treatment includes at least one of sodium hydroxide, potassium carbonate and potassium hydroxide, and the mass ratio of the alkalizing agent to the corn cob powder is (0.1-0.3):1;

[0011] During the alkalization treatment, the corn cob powder is soaked in an alkaline solution for 2 to 3 days, and stirred for 2 to 4 hours every day;

[0012] The alkalization treatment breaks the connection structure of cellulose, hemicellulose and lignin in the corn cob, and better decomposes the components such as hemicellulose, lignin, protein, sugar, etc. Among them, hemicellulose and lignin are dissolved in alkaline water and discharged; sugar and starch are dissolved in water and discharged.

[0013] (2) Neutralization treatment: neutralizing the corn cob powder to remove excess starch and sugar;

[0014] Specifically, the corn cob powder after the alkalization treatment is placed in a soaking tank for 6-12 hours, the overflow port is opened to discharge the sewage, and clean water is added and stirred for 2-3 hours; this is repeated 2-4 times until the pH value is 6-7; after the neutralization is completed, the corn cob powder is centrifuged and dehydrated to obtain a semi-finished corn cob powder.

[0015] (3) acidification treatment; acidifying the corn cob powder to remove excess lipids to form acidified corn cob powder; wherein:

[0016] The acidifying agent for the acidification treatment is glacial acetic acid or aminosulfonic acid, and the mass ratio of the acidifying agent to the corn cob powder is (0.25-0.5):1; during the acidification treatment, the corn cob powder is immersed in the acidification solution for 2 to 3 days, and stirred for 4 to 6 hours every day; before each stirring, the overflow port is opened to remove lipids and impurities floating on the surface of the slurry.

[0017] (4) nitration treatment; i.e., using nitric acid, a nitrating agent, to nitrate the acidified corn cob powder to form nitrated corn cob fiber rubber powder; specifically, cooling concentrated nitric acid with a concentration of 98% to below 25° C. in a cooler, adding the acidified corn cob powder in multiple portions, continuing cooling, and stirring the addition for 35 min to 45 min, wherein the mass ratio of the nitrated corn cob fiber rubber powder to the concentrated nitric acid is 1:(0.7-1); after the nitration is completed, filtering and separating the liquid nitric acid for reuse;

[0018] The nitration reaction can remove organic matter in the corn cob powder to generate a semi-finished corn cob fiber rubber powder containing only carbon elements, so that the corn cob fiber rubber powder prepared in the subsequent steps will not generate smoke when burned and will not leave a large amount of residue after the combustion is completed;

[0019] Since a large amount of heat is released during the nitration reaction, the present invention uses cold nitric acid within 25 degrees for nitration, which can greatly reduce the amount of heat released during the reaction and slow down the heating rate of the reaction system, which is conducive to achieving the purpose of temperature control of the reaction system, thereby further enhancing the stability of the product;

[0020] On this basis, since the acidified corn cob powder and the reagents used in the nitrification process are both acidic, the stability of the raw materials and reagents during the reaction is relatively high, reducing the chance of accidents.

[0021] (5) neutralizing the nitrated corn cob fiber rubber powder; that is, the nitrated corn cob fiber rubber powder is not put into a neutralization tank containing a neutralizing agent, but is neutralized to a pH of 6-7; the neutralizing agent is sodium bicarbonate, and the mass ratio of sodium bicarbonate to corn cob powder is (0.04-0.08):1; after neutralization, the powder is rinsed, centrifuged and dehydrated, and dried or air-dried; the moisture content of the resulting corn cob fiber rubber powder semi-finished product is ≤8%, and the water discharged during the neutralization process can be reused.

[0022] (6) The semi-finished corn cob fiber rubber powder product is subjected to oxidation treatment and a stabilizer is added to obtain a stable corn cob fiber rubber powder product, i.e., corn cob nitrocellulose; specifically, potassium nitrate, diphenylamine and the semi-finished corn cob fiber rubber powder product are reacted under heating conditions; the specific operation is as follows:

[0023] First, the semi-finished corn cob fiber rubber powder is placed in a reactor for stirring and preheating, the preheating temperature is 110°C to 135°C, and the preheating time is 30min to 45min, and then potassium nitrate and diphenylamine are added to the reactor for further reaction; in this process, since the semi-finished corn cob fiber rubber powder is preheated, the heating time of the semi-finished corn cob fiber rubber powder, potassium nitrate and diphenylamine can be shortened, thereby accelerating the reaction progress and reducing production energy consumption; controlling the semi-finished corn cob fiber rubber powder, potassium nitrate and diphenylamine The mass ratio of amine is 1:(0.02-0.2):(0.01-0.08), the reaction temperature is 110°C-135°C, and the reaction time is 35min-45min. Within the above ratio and parameter range, the three have the best dispersion performance and the highest reaction efficiency, so that the product not only contains oxygen elements, but also forms an antioxidant protective film on the surface of the product, which can maximize the product's explosive power, antioxidant ability, and anti-corrosion ability, and ensure that the product will not produce odor or a large amount of residue during combustion;

[0024] After the reaction is completed, put it into a stainless steel pool, stir and cool for 1 hour, rinse, centrifuge and dehydrate, and dry it to make its moisture ≤5%;

[0025] Finally, a stabilizer is added to form a finished product of corn cob fiber rubber powder, namely corn cob nitrocellulose;

[0026] The above materials are put into a stainless steel mixer, and the prepared stabilizer is sprayed in while stirring to enhance the stability of the product and reduce the occurrence of explosion accidents. The stabilizer includes camphor and alcohol. In this process, the mass ratio of corn cob fiber rubber powder to camphor and alcohol is 1: (0.1-0.7): (0.5-0.95). After the stirring and spraying is completed, the product is air-dried at low temperature until the alcohol evaporates, so as to form corn cob fiber rubber powder, namely corn cob nitrocellulose.

[0027] Under the synergistic effect of the above steps, corn cob fiber rubber powder is prepared, which has strong stability, good environmental protection, excellent combustion performance, no smoke, no odor, and only produces trace residues after combustion. The powder belongs to low-purity corn cob nitrocellulose.

[0028] Wastewater and waste residue generated during the preparation process are treated in accordance with national statutory regulations, and the neutralized water generated during the production process and the water generated after material centrifugation can be recycled, so corn cob fiber rubber powder can be produced with low energy consumption and high environmental protection.

[0029] In addition, the preparation method of the corn cob fiber rubber powder provided by the present invention is simple and easy, and does not require the use of large-scale equipment (such as a boiler). Only ordinary machinery and equipment, mixers and other equipment are needed to complete the preparation process of the product, thereby reducing production energy consumption.

[0030] The method for preparing corn cob fiber rubber powder provided by the present invention comprises the following steps: firstly subjecting the corn cob powder to an alkalization treatment so that the corn cob powder is easier to hydrolyze, the connection structure of cellulose, hemicellulose and lignin of the corn cob is broken, and hemicellulose, lignin, protein, sugar and other components are better decomposed; wherein hemicellulose and lignin are dissolved in alkaline water and discharged; sugar and starch are dissolved in water and discharged; and then subjecting the corn cob powder to an acidification treatment so that the corn cob powder is acidic and impurities and lipids in the corn cob powder are removed, thereby facilitating the preparation of corn cob fiber rubber powder that meets the expected effect from the corn cob powder in the subsequent processing; and subjecting the acidified corn cob powder to a nitration treatment. Since the acidified corn cob powder and the reagents used in the nitration process are both acidic, the stability of the raw materials and the reagents during the reaction process is relatively high, thereby reducing the probability of accidents; and in the reaction process, organic matter in the acidified corn cob powder is removed , generating a semi-finished corn cob fiber rubber powder containing only carbon elements, so that the corn cob fiber rubber powder prepared in the subsequent steps will not produce smoke when burned, and will not leave a large amount of residue after the combustion is completed; the corn cob fiber rubber powder semi-finished product is preheated and then reacted with potassium nitrate and diphenylamine under heating conditions to shorten the reaction time of the corn cob fiber rubber powder semi-finished product with potassium nitrate and diphenylamine, accelerate the reaction progress, and reduce production energy consumption; in the heating reaction process of the above raw materials, the dispersion performance of the three is good, so that the product not only contains oxygen elements, but also forms an antioxidant protective film on the surface of the product, and further makes the product only produce trace residues after the combustion is completed; and because potassium nitrate is used as an oxidant, it is ensured that the prepared corn cob fiber rubber powder will not produce odor, so it is more environmentally friendly; adding a stabilizer after the reaction is completed can enhance the stability of the product and reduce the occurrence of explosion accidents.

[0031] In addition, the preparation method of the corn cob fiber rubber powder provided by the present invention is simple and easy, the equipment is safe and readily available, and the energy consumption is low.

[0032] The corn cob fiber rubber powder prepared by the preparation method of the invention can be used as an additive material for various safe and environmentally friendly fireworks, coatings and other products.

[0033] The application of the corn cob fiber rubber powder provided by the present invention in the field of fireworks and firecrackers, as an oxidant and synergist, helps the combustion process of fireworks to be more intense, and enhances the explosion effect and brightness of fireworks and firecrackers. In the process of making fireworks and firecrackers, the mass content of the corn cob fiber rubber powder provided by the present invention is roughly between 15% and 35%, and the proportion varies depending on the different types and formulas of fireworks and firecrackers. For example: flash fireworks will use a higher proportion in order to enhance the brightness and explosion effect. Rocket-type fireworks or artillery-type fireworks require higher energy, and the proportion used will be higher. The proportion used in smoke bombs or lower-energy fireworks may be lower, and more dependent on other chemical components.

[0034] The test results of Examples 1 to 3 show that the corncob fiber rubber powder provided by the present invention has no odor or smoke when burned, and only produces a trace amount of residue. The mass ratio of the trace amount of residue to the corncob fiber rubber powder is (0.01-0.05):1. The main components of the trace amount of residue are potassium metal compounds, as well as metal compounds of calcium, magnesium, iron and other metals, which are very small and will not cause pollution to the environment.

[0035] The application of the corn cob fiber rubber powder provided by the present invention in the field of coatings can be used as the core component of environmentally friendly nitro lacquer. As a film-forming material, it can provide adhesion and strength of the paint film and has the advantage of fast drying. It usually accounts for 10%-30% of the mass of the paint liquid. If a higher proportion is added, the hardness and wear resistance of the paint film can be increased; if a lower proportion is added, better fluidity and gloss effect can be provided, which is suitable for applications with high requirements for surface smoothness and color. The main components of environmentally friendly nitro lacquer also include the following: alcohol solvents, low-volatile pigments, resins or plasticizers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The preparation flow chart of corncob nitrocellulose provided in this example is shown. DETAILED DESCRIPTION

[0037] The present invention is further described below by way of examples.

[0038] Example 1

[0039] The method for preparing corn cob fiber rubber powder provided in Example 1 of the present invention comprises the following steps:

[0040] Step 1, alkalization treatment; crush the dried corn cobs into 60 mesh, put them into a soaking tank with a mixer, add clean water at a mass ratio of 1:4 between corn cob powder and water, add potassium hydroxide and potassium carbonate at 15% of the weight of the corn cob powder; soak for 3 days, stirring for 2 hours every day;

[0041] Step 2, neutralization treatment; filter and dry the alkalized corn cob powder, put it into the neutralization tank, stir it, and rinse it to a pH value of 6-7;

[0042] Step 3, acidification treatment; after filtering and drying the neutralized corn cob powder, put it into a soaking tank with a mixer, add clean water according to the mass ratio of corn cob powder to water of 1:4, and add glacial acetic acid according to 35% of the weight of the corn cob powder; soak for 2 days, stir for 4 hours every day, then take out the material, centrifuge and dry it, and air-dry it to form acidified corn cob powder;

[0043] Step 4, nitration treatment; the nitration process and process technology are carried out according to the nitration process specified by the state; the nitric acid is cooled to below 25°C in a cooler, and then the acidified corn cob powder is slowly added, the nitric acid concentration is 98%, the mass ratio of the powder to the concentrated nitric acid is 1:0.75, the cooling and stirring time is 55 minutes, and after the nitration is completed, the nitration is cooled and filtered to form a nitrated corn cob powder;

[0044] Step 5, neutralization treatment again; put the nitrated corn cob powder into a neutralization tank for neutralization treatment, add water, add sodium bicarbonate according to the weight ratio of 6% of the corn cob powder, neutralize to a pH value of 6-7, rinse the corn cob powder, centrifuge dehydrate, and air-dry to form a semi-finished corn cob fiber powder with a moisture content of no more than 8%;

[0045] Step 6, oxidation treatment; put the corn cob fiber powder semi-finished product into a reactor for preheating, stirring and preheating for 30 to 40 minutes, the preheating temperature is 135°C, then put 2.5% potassium nitrate by weight of the corn cob powder and 1% diphenylamine by weight of the corn cob powder into the reactor, continue stirring and heating for 40 minutes, the temperature is 135°C; after stirring and cooling for 60 minutes, take out the corn cob powder for rinsing, centrifugal dehydration, and low-temperature air drying to form a corn cob fiber rubber powder semi-finished product with a moisture content of no more than 5%; put the corn cob fiber rubber powder semi-finished product into a stainless steel mixer, while stirring, spray 70% of the stabilizer by weight of the corn cob powder, the stabilizer is composed of camphor and alcohol, and the weight ratio of camphor to alcohol is 2:5, and the corn cob fiber rubber powder with the stabilizer added is low-temperature air-dried to form a corn cob fiber rubber powder finished product.

[0046] Example 2

[0047] The method for preparing corn cob fiber rubber powder provided in Example 2 of the present invention comprises the following steps:

[0048] Step 1, alkalization treatment; crush the dried corn cobs into 70 meshes, put them into a soaking tank with a mixer, add clean water according to the mass ratio of corn cob powder to water of 1:4, and add sodium hydroxide according to 15% of the weight of the corn cob powder; soak for 3 days, stirring for 2 hours every day;

[0049] Step 2, neutralization treatment; filter and dry the alkalized corn cob powder, put it into the neutralization tank, stir it, and rinse it to a pH value of 6-7;

[0050] Step 3, acidification treatment; after filtering and drying the neutralized corn cob powder, put it into a soaking tank with a mixer, add clean water according to the mass ratio of corn cob powder to water of 1:4, and add glacial acetic acid according to 35% of the weight of the corn cob powder; soak for 2 days, stir for 5 hours every day, then take out the material, centrifuge and dry it, and air-dry it to form acidified corn cob powder;

[0051] Step 4, nitration treatment; the nitration process and process technology are carried out according to the nitration process specified by the state; the nitric acid is cooled to below 25°C in a cooler, and then the acidified corn cob powder is slowly added, the nitric acid concentration is 98%, the mass ratio of the powder to the concentrated nitric acid is 1:0.85, the cooling and stirring time is 45 minutes, and after the nitration is completed, the nitration is cooled and filtered to form a nitrated corn cob powder;

[0052] Step 5, neutralization treatment again; put the nitrated corn cob powder into a neutralization tank for neutralization treatment, add water, add sodium bicarbonate according to the weight ratio of 7.5% of the corn cob powder, neutralize to a pH value of 6-7, rinse the corn cob powder, centrifuge dehydrate, and air-dry to form a semi-finished corn cob fiber powder with a moisture content of no more than 8%;

[0053] Step 6, oxidation treatment; put the corn cob fiber powder semi-finished product into a reactor for preheating, stirring and preheating for 30 to 40 minutes, the preheating temperature is 135°C, then put 2.5% potassium nitrate by weight of the corn cob powder and 1% diphenylamine by weight of the corn cob powder into the reactor, continue stirring and heating for 40 minutes, the temperature is 135°C; after stirring and cooling for 60 minutes, take out the corn cob powder, rinse, centrifuge and dehydrate, and air-dry at low temperature to form a corn cob fiber rubber powder semi-finished product with a moisture content of no more than 5%; put the corn cob fiber rubber powder semi-finished product into a stainless steel mixer, stir while spraying 70% of the stabilizer by weight of the corn cob powder, the stabilizer is composed of camphor and alcohol, the weight ratio of camphor to alcohol is 2:5, and the corn cob fiber rubber powder with the stabilizer added is air-dried at low temperature to form a corn cob fiber rubber powder finished product.

[0054] Example 3

[0055] The method for preparing corn cob fiber rubber powder provided in Example 3 of the present invention comprises the following steps:

[0056] Step 1, alkalization treatment; crush the dried corn cobs into 80 meshes, put them into a soaking tank with a mixer, add clean water according to the mass ratio of corn cob powder to water of 1:4, and add sodium hydroxide according to 15% of the weight of the corn cob powder; soak for 3 days, stirring for 2 hours every day;

[0057] Step 2, neutralization treatment; filter and dry the alkalized corn cob powder, put it into the neutralization tank, stir it, and rinse it to a pH value of 6-7;

[0058] Step 3, acidification treatment; after filtering and drying the neutralized corn cob powder, put it into a soaking tank with a mixer, add clean water according to the mass ratio of corn cob powder to water of 1:4, and add aminosulfonic acid according to 45% of the weight of the corn cob powder; soak for 2 days, stir for 5 hours every day, then take out the material, centrifuge and dry it, and air-dry it to form acidified corn cob powder;

[0059] Step 4, nitration treatment; the nitration process and process technology are carried out according to the nitration process specified by the state; the nitric acid is cooled to below 25°C in a cooler, and then the acidified corn cob powder is slowly added, the nitric acid concentration is 98%, the mass ratio of the powder to the concentrated nitric acid is 1:0.85, the cooling and stirring time is 45 minutes, and after the nitration is completed, the nitration is cooled and filtered to form a nitrated corn cob powder;

[0060] Step 5, neutralization treatment again; put the nitrated corn cob powder into a neutralization tank for neutralization treatment, add water, add sodium bicarbonate according to the weight ratio of 7.5% of the corn cob powder, neutralize to a pH value of 6-7, rinse the corn cob powder, centrifuge dehydrate, and air-dry to form a semi-finished corn cob fiber powder with a moisture content of no more than 8%;

[0061] Step 6, oxidation treatment; put the corn cob fiber powder semi-finished product into a reactor for preheating, stirring and preheating for 30 to 40 minutes, the preheating temperature is 135°C, then put 2.5% potassium nitrate by weight of the corn cob powder and 1% diphenylamine by weight of the corn cob powder into the reactor, continue stirring and heating for 40 minutes, the temperature is 135°C; after stirring and cooling for 60 minutes, take out the corn cob powder for rinsing, centrifugal dehydration, and low-temperature air drying to form a corn cob fiber rubber powder semi-finished product with a moisture content of no more than 5%; put the corn cob fiber rubber powder semi-finished product into a stainless steel mixer, while stirring, spray 70% of the stabilizer by weight of the corn cob powder, the stabilizer is composed of camphor and alcohol, and the weight ratio of camphor to alcohol is 2:5, and the corn cob fiber rubber powder with the stabilizer added is low-temperature air-dried to form a corn cob fiber rubber powder finished product.

[0062] Comparative Example 1

[0063] The first step is to prepare alkalized corn cob powder: firstly, put the corn cob powder with a fineness of 80 meshes into a soaking tank with a mixer, add water into the soaking tank according to the mass ratio of corn cob powder to water of 1:4, and then add an appropriate amount of alkali solution; soak the corn cob powder in the soaking tank for 3 days, stir for 6 hours every day, centrifuge the material after the alkalization, dry it, and air-dry it to form alkalized corn cob powder; the water generated after the centrifugation of the material is returned to the soaking tank for recycling.

[0064] The second step is to prepare a semi-finished corn cob fiber rubber powder product: concentrated sulfuric acid, fuming nitric acid and water are weighed respectively according to the mass ratio of (60-70): (20-30): (10-25) to prepare a mixed acid solution; the alkalized corn cob powder is added to the mixed acid solution, stirred at room temperature for 15-45 minutes, and then the stirring is stopped; after nitration is completed, the product enters into cooling filtration separation; wherein the mass ratio of nitrated corn cob fiber rubber powder to concentrated nitric acid is 1:0.1; the filtered nitric acid is returned to the cooler and reused; finally, the nitrated corn cob fiber rubber powder is put into a neutralization tank for neutralization treatment until the pH value is 7; the neutralizing agent is sodium bicarbonate, and the mass ratio of sodium bicarbonate to corn cob powder is 0.1:1; after neutralization, the product is rinsed, centrifuged and dried; the moisture content of the generated corn cob fiber rubber powder semi-finished product is equal to 7%, and the neutralization water is reused.

[0065] The third step is to prepare corn cob fiber rubber powder: potassium nitrate, diphenylamine and corn cob fiber rubber powder semi-finished product are put into a reactor, the mass ratio of corn cob fiber rubber powder semi-finished product, potassium nitrate and diphenylamine is 1:0.02:0.015, the reaction temperature is 145°C, and the reaction time is 35 minutes. After the reaction is completed, it is put into a stainless steel pool, stirred and cooled for 1 hour, rinsed, centrifuged, and dried to make its moisture equal to 2%; finally, the above materials are put into a stainless steel mixer, and while stirring, the prepared stabilizer is sprayed in, the mass ratio of corn cob fiber rubber powder to stabilizer is 1:1; the stabilizer includes camphor and alcohol, and the mass ratio of camphor to alcohol is 3:7. After the spraying is completed, the product is air-dried to form corn cob fiber rubber powder.

[0066] In order to test the effect of the corn cob fiber rubber powder provided by the present invention, the thermal stability, moisture absorption rate, friction sensitivity, impact sensitivity, ignition temperature, sulfur content and chlorate content of the product are tested. The inspection and judgment are based on: AQ 4104-2008 "Safety Performance Index and Determination Method of Fireworks and Firecrackers Pyrotechnic Powder", GB / T 15814.1-2010 "Qualitative Determination of Fireworks and Firecrackers Powder Components", GB / T 21242-2019 "Qualitative Detection Method of Fireworks and Firecrackers Prohibited and Restricted Powder".

[0067] in:

[0068] The 75℃ thermal stability of a product means that if 100g of a sample is placed in an oven at 75℃±2℃ for 48 hours without any combustion or explosion, it is qualified.

[0069] The product is qualified if its moisture absorption rate is less than or equal to 4%.

[0070] The friction sensitivity of the product is qualified if it is less than or equal to 60% when the swing angle is 70 degrees and the hydraulic pressure is 1.23MP.

[0071] The product impact sensitivity is qualified if it is less than or equal to 50% when the hammer weight is 10kg and the hammer height is 250mm.

[0072] Table 1 shows the performance parameters of the corncob fiber rubber powder prepared in Examples 1 to 3 of the present invention.

[0073] Table 1

[0074] Serial number Thermal stability Moisture absorption rate friction sensitivity Impact sensitivity Ignition temperature Sulfur content Chlorate content Residue Example 1 No burning 1.21％ 51.3％ qualified 175.9 Not detected Not detected Trace Example 2 No burning 1.20％ 51.2％ qualified 176.0 Not detected Not detected Trace Example 3 No burning 1.19％ 51％ qualified 175.9 Not detected Not detected Trace Comparative Example 1 combustion 1.50％ 55％ qualified 75.1 Not detected Not detected Trace .

[0075] It can be seen from the above that the thermal stability, moisture absorption rate, friction sensitivity and impact sensitivity of the product prepared by the preparation method provided by the embodiment of the present invention are all qualified, indicating that the product is relatively safe and has a high yield. In addition, no sulfur and chlorate were detected in the above products, indicating that the above products have no peculiar smell, no smoke when burning, and only produce a trace amount of residue. The thermal stability of the product prepared in comparative example 1 is poor, because it is degreased by alkalization treatment, so that the prepared corn cob powder is alkaline, which is different from the properties of the reagents of nitration treatment, and during nitration, mixed acid nitration is adopted at room temperature, and the heat released is large, so it has poor thermal stability.

[0076] The above is only a specific embodiment of the present invention. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and the drawings are only exemplary illustrations of the present invention as defined by the attached claims, and are deemed to have covered any and all modifications, changes, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and variations. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A method for preparing corncob nitrocellulose, characterized in that: The specific steps are: (1) Alkalization treatment: the corn cob powder is subjected to alkalization treatment to form easily hydrolyzed corn cob powder and remove hemicellulose and lignin; (2) Neutralization treatment: neutralizing the corn cob powder to remove excess starch and sugar; (3) Acidification treatment: Acidification treatment is performed on the corn cob powder to remove excess lipids to form acidified corn cob powder; (4) Nitration treatment: using nitric acid, a nitrating agent, to nitrate the acidified corn cob powder to form nitrated corn cob fiber rubber powder; (5): neutralizing the nitrated corn cob powder; that is, putting the nitrated corn cob fiber rubber powder into a neutralization tank containing a neutralizing agent for neutralization to a pH of 6-7; (6): The corn cob fiber rubber powder semi-finished product is subjected to oxidation treatment and a stabilizer is added to obtain a stable corn cob fiber rubber powder product, namely corn cob nitrocellulose.

2. The preparation method according to claim 1, characterized in that: In step (1), the fineness of the corn cob powder is 60-80 mesh; the alkalizing agent for the alkalization treatment is at least one of sodium hydroxide, potassium carbonate, and potassium hydroxide, and the mass ratio of the alkalizing agent to the corn cob powder is (0.1-0.3):1; The alkalization treatment is to soak the corn cob powder in an alkaline solution for 2 to 3 days and stir for 2 to 4 hours every day.

3. The preparation method according to claim 2, characterized in that: The neutralization treatment in step (2) is to place the corn cob powder after the alkalization treatment in a soaking tank for 6-12 hours, open the overflow port to discharge the sewage, fill it with clean water and stir for 2-3 hours; repeat 2-4 times until the pH value is 6-7; after the neutralization is completed, the corn cob powder is centrifuged and dehydrated to obtain a corn cob powder intermediate.

4. The preparation method according to claim 3, characterized in that: In step (3), the acidifying agent used for the acidification treatment is glacial acetic acid or aminosulfonic acid, and the mass ratio of the acidifying agent to the corn cob powder is (0.25-0.5):1; during the acidification treatment, the corn cob powder is immersed in the acidification solution for 2 to 3 days, stirred for 4 to 6 hours every day, and the overflow port is opened before each stirring to remove lipids and impurities floating on the surface of the slurry.

5. The preparation method according to claim 4, characterized in that: The nitration treatment in step (4) is to cool concentrated nitric acid with a concentration of 98% to below 25° C. in a cooler, add acidified corn cob powder in multiple times, continue cooling, and stir the addition for 35 min to 45 min. The mass ratio of nitrated corn cob fiber rubber powder to concentrated nitric acid is 1:(0.7~1). After the nitration is completed, the liquid nitric acid is filtered and separated for reuse.

6. The preparation method according to claim 5, characterized in that: The neutralizing agent used in the neutralization treatment in step (5) is sodium bicarbonate, and the mass ratio of sodium bicarbonate to corn cob powder is (0.04-0.08):1; after neutralization, the corn cob fiber powder is rinsed, centrifuged and dehydrated, and dried or air-dried; the moisture content of the resulting corn cob fiber rubber powder semi-finished product is ≤8%.

7. The preparation method according to claim 6, characterized in that: The oxidation treatment in step (6) is specifically performed as follows: First, the semi-finished corn cob fiber rubber powder is placed in a reactor for stirring and preheating, the preheating temperature is 110°C~135°C, and the preheating time is 30min~45min, and then potassium nitrate and diphenylamine are added to the reactor to continue the reaction; the mass ratio of the semi-finished corn cob fiber rubber powder, potassium nitrate and diphenylamine is controlled to be 1: (0.02~0.2): (0.01~0.08), the reaction temperature is 110°C~135°C, and the reaction time is 35min~45min; after the reaction is completed, it is placed in a stainless steel pool, stirred and cooled for 1 hour, rinsed, centrifuged and dehydrated, and dried to make its moisture ≤5%; Finally, a stabilizer is added to form a finished product of corn cob fiber rubber powder; specifically, the above materials are put into a stainless steel mixer, and the prepared stabilizer is sprayed in while stirring; the stabilizer includes camphor and alcohol. In this process, the mass ratio of corn cob fiber rubber powder to camphor and alcohol is 1: (0.1-0.7): (0.5-0.95). After the stirring and spraying is completed, the product is air-dried at low temperature until the alcohol evaporates, thereby forming corn cob fiber rubber powder.

8. A corncob nitrocellulose obtained by the preparation method according to any one of claims 1 to 7, wherein the corncob nitrocellulose has excellent combustion performance, is smokeless and odorless, and has only a trace amount of residue after combustion.

9. Use of the corn cob fiber rubber powder as claimed in claim 8 as an additive for fireworks and coatings.

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