Preparation method of sealer, sealer and protection method of iron articles

Abstract

The present invention provides a method for preparing a protective agent, a protective agent, and a method for protecting iron articles. The method for preparing the protective agent of the present invention comprises the following steps: Step (i): dispersing nanocellulose, triethanolamine, and 4-(dimethylamino)pyridine in a first organic solvent to obtain a nanocellulose dispersion, and dispersing acyl chlorinated wax in a second organic solvent to obtain an acyl chlorinated wax dispersion; Step (ii): mixing the above-mentioned acyl chlorinated wax dispersion with the above-mentioned nanocellulose dispersion, and performing an esterification reaction to obtain a nanocellulose-based wax graft; and Step (iii): dispersing the above-mentioned nanocellulose-based wax graft in a third organic solvent to obtain the above-mentioned protective agent. According to the present invention, effective and reversible protection of iron articles can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of protection of iron articles, and more specifically, to a preparation method of a protective agent, a protective agent, and a protection method of iron articles. Background Art

[0002] However, due to the active chemical properties of iron elements, they are prone to chemical corrosion, electrochemical corrosion, and bacterial corrosion in the natural environment, resulting in the embrittlement of the texture of iron cultural relics and the deterioration of chemical stability. At the same time, there are still risks of deformation, continuous corrosion, damage, and weathering and fragmentation of fragile iron cultural relics during the processes of unearthed, preservation, and exhibition. Therefore, the protection of fragile iron cultural relics is particularly important.

[0003] The technology of using protective agents can not only maintain the mechanical strength and structural stability of fragile iron cultural relics, but also greatly slow down the speed of oxygen, moisture, and other corrosion factors reaching their surfaces, delaying or even avoiding their continuous corrosion. Currently, the most commonly used protective materials for fragile iron cultural relics are acrylic resins, polyurethanes, microcrystalline waxes, etc. Among them, acrylic resins, polyurethanes, etc. have good film-forming properties but are not easy to remove; the oxygen permeability of microcrystalline wax is relatively high, and there is still a possibility of corrosion of cultural relics. In addition, it is also considered to add nanomaterials such as SiO2 and TiO2 as additives to traditional organic protective agents to form a uniform and dense film to improve the barrier properties to water and oxygen. However, during the on-site protection process of cultural relics, due to the uneven dispersion liquid, it is difficult to use and the effect is not ideal.

[0004] Therefore, it is urgent to develop a new type of protective agent for real-time, rapid, and effective protection of iron articles, especially fragile iron cultural relics.

[0005] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present invention, and therefore it may include information that does not constitute the prior art known to those skilled in the art. Summary of the Invention

[0006] In order to solve one or more of the above problems existing in the prior art, the present invention provides a preparation method of a protective agent, a protective agent, and a protection method of iron articles.

[0007] The preparation method of the protective agent of the present invention comprises the following steps: Step (i): Dispersing nanocellulose, triethanolamine and 4-(dimethylamino)pyridine in a first organic solvent to obtain a nanocellulose dispersion, and dispersing acyl chlorinated wax in a second organic solvent to obtain an acyl chlorinated wax dispersion; Step (ii): Mixing the above-mentioned acyl chlorinated wax dispersion with the above-mentioned nanocellulose dispersion, and performing an esterification reaction to obtain a nanocellulose-based wax graft; and Step (iii): Dispersing the above-mentioned nanocellulose-based wax graft in a third organic solvent to obtain the above-mentioned protective agent, wherein the above-mentioned nanocellulose is any one or more of nanocrystalline cellulose, nanofibrillated cellulose, cationized nanofibrillated cellulose and bacterial cellulose whiskers, the above-mentioned first organic solvent is any one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide and pyridine, the above-mentioned second organic solvent is any one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide and pyridine, and the above-mentioned third organic solvent is any one or more of acetone, ethanol, methanol, dichloromethane, benzene and toluene.

[0008] According to an embodiment of the present invention, in the above step (i), the mass ratio of the above-mentioned nanocellulose, the above-mentioned first organic solvent, the above-mentioned triethanolamine, and the above-mentioned 4-(dimethylamino)pyridine can be 1:20:0.05:0.01 to 1:5:0.05:0.05, the mass ratio of the above-mentioned acyl chlorinated wax to the above-mentioned second organic solvent can be 1:5 to 1:20, and the mass ratio of the above-mentioned acyl chlorinated wax to the above-mentioned nanocellulose can be: 0.5:1 to 5:1.

[0009] According to an embodiment of the present invention, in the above step (ii), the above-mentioned nanocellulose dispersion can be cooled to 0 °C by ice bath and continuously stirred, the above-mentioned acyl chlorinated wax dispersion is added dropwise to the above-mentioned nanocellulose dispersion, and after performing an esterification reaction at a temperature of 25 to 90 °C for 120 to 360 min, the reaction solution is collected and dialyzed using a dialysis bag for 2 to 5 days, and then freeze-dried to obtain the above-mentioned nanocellulose-based wax graft.

[0010] According to an embodiment of the present invention, the above-mentioned acyl chlorinated wax can be obtained by mixing oxidized wax and toluene in a mass ratio of 1:5 to 1:20, and then adding an acylating agent to perform an acylation reaction, wherein the above-mentioned acylating agent can be any one or more of thionyl chloride, phosphorus pentachloride, oxalyl chloride and phosphorus trichloride, and the mass ratio of the above-mentioned acylating agent to the above-mentioned oxidized wax can be 2:1 to 5:1.

[0011] According to an embodiment of the present invention, the above-mentioned acylation reaction can be carried out under the condition of heating and refluxing at a temperature of 50 to 80 °C for 30 to 120 min.

[0012] According to an embodiment of the present invention, the above-mentioned oxidized wax can be obtained by mixing dimethyl silicone oil and wax in a mass ratio of 20:1 to 2:1, and then subjecting the wax to an oxidation reaction in the presence of a catalyst and air. The wax can be any one or more of polyethylene wax, microcrystalline wax, palm wax, beeswax, shellac, and insect white wax. The catalyst can be any one or more of stannous octoate, magnesium stearate, potassium permanganate, and cobalt acetate.

[0013] According to an embodiment of the present invention, the above-mentioned oxidation reaction can be carried out at 60-150 °C for 30-90 min, and the mass ratio of the wax to the catalyst can be 5:1 to 50:1.

[0014] In addition, the protective agent of the present invention is prepared by the preparation method of the above-mentioned protective agent.

[0015] In addition, the reinforcement method of the iron articles of the present invention includes covering the surface of the above-mentioned iron articles with the above-mentioned protective agent.

[0016] According to an embodiment of the present invention, the above-mentioned iron articles can be iron cultural relics.

[0017] According to the preparation method of the protective agent, the protective agent, and the protection method of the iron articles provided by the present invention, effective and reversible protection of the iron articles can be achieved. Detailed Description of the Invention

[0018] The present invention will be described in detail below through specific embodiments, so that those of ordinary skill in the art can easily implement the present invention according to the content disclosed in this specification. The following described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments described in this specification without creative efforts belong to the scope of protection of the present invention. It should be noted that, without conflict, the embodiments in this specification and the features in the embodiments can be combined with each other.

[0019] The inventor of the present invention considered using nanocellulose to prepare a new type of protective agent. Nanocellulose is a kind of high-strength biomass material, usually including nanocrystalline cellulose (CNC), nanofibrillated cellulose (CNF), and bacterial cellulose whiskers (BNCW). After drying the aqueous dispersion of nanocellulose, nanocellulose can form a dense structure to form a film with excellent oxygen barrier performance. For example, when CNC is coated on paper with a coating amount of 0.2 g / m 2 , the oxygen transmission rate of the coated paper will be reduced to 1 / 3 of the original. When CNF is coated on the surface of greaseproof paper and kraft wrapping paper with a coating amount of 0.6 g / m 2, the oxygen transmission rate is reduced to 1 / 100 of the original paper. However, after the nanocellulose forms a film, it contacts closely with the surface of iron objects, especially iron cultural relics, and needs to be repeatedly cleaned to be completely removed. However, during this process, it is easy to cause further damage to iron objects, especially fragile iron cultural relics. At the same time, due to the large amount of hydroxyl groups in nanocellulose, if it is not modified, it will have a certain hygroscopicity, resulting in poor water vapor barrier performance. Therefore, the inventor of the present invention is committed to improving the ability of nanocellulose to be reversibly and completely removed and block water vapor after forming a film, so as to perform real-time, rapid and effective protection on iron objects, especially fragile iron cultural relics. Based on this, the present invention is completed.

[0020] That is, the preparation method of the present invention is to mix a specific acyl chloride wax dispersion liquid with a specific nanocellulose dispersion liquid to carry out an esterification reaction, and then disperse the nanocellulose-based wax grafted product into an organic solution to obtain the novel protective agent of the present invention.

[0021] Using the protective agent prepared by the preparation method provided by the present invention, the nanocellulose-based wax grafted product is used for the protection of iron objects, especially fragile iron cultural relics. While retaining the good film-forming property of nanocellulose, the fluidity is improved by introducing wax as a graft, so as to realize effective and reversible protection of fragile iron cultural relics.

[0022] Specifically, the preparation method of the protective agent of the present invention may include the following steps: (1) preparing oxidized wax; (2) preparing acyl chloride wax; (3) preparing nanocellulose-based wax grafted product; (4) preparing a nanocellulose-based wax grafted product dispersion liquid, that is, the protective agent of the present invention.

[0023] First of all, in step (1), it can be carried out through the following operations. Add a predetermined proportion of dimethyl silicone oil and wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt. Raise the temperature of the oil bath to the reaction temperature, add a catalyst after stabilizing for a predetermined time, turn on the air pump to start the reaction. After reacting for a predetermined time, turn off the air pump, stop heating, pour out the mixture in the four-necked flask, and filter the product by suction after cooling to obtain a crude product, and obtain oxidized wax after washing with hot water.

[0024] Among them, the mass ratio of dimethyl silicone oil to wax is 20:1 to 2:1, preferably 10:1 to 5:1. This is because if this ratio is too small, the wax is not evenly dispersed, and if the ratio is too large, the subsequent yield will be reduced.

[0025] In addition, the wax used is any one or more of polyethylene wax, microcrystalline wax, palm wax, white beeswax, shellac and Chinese wax. Preferably any one or more of polyethylene wax, microcrystalline wax and white beeswax. This is because these three kinds of waxes have the advantages of high softening point, low viscosity and high transparency, meeting the requirement of not changing the color during the subsequent protection of iron cultural relics.

[0026] In addition, the reaction temperature of the oil bath is 60-150 °C. Considering that if the temperature is too low, the wax will not melt; if the temperature is too high, there is a risk of wax combustion, and at the same time, the alkane molecules in the wax will crack, so the preferred reaction temperature is 60-100 °C.

[0027] In addition, the stabilization time is 30-90 min. Considering that if the time is too short, the wax will not melt evenly, and to ensure the full melting of the wax, it is preferably 30-60 min.

[0028] In addition, the catalyst is any one or more of stannous octoate, magnesium stearate, potassium permanganate and cobalt acetate. The preferred catalyst is stannous octoate and / or potassium permanganate. This is because these two catalysts have high catalytic activity and selectivity, can catalyze the conversion of the substrate under mild conditions, and at the same time maintain good catalytic life and renewable performance.

[0029] In addition, considering that too little catalyst will lead to insufficient reaction, and too much will increase costs and waste, which is not easy to remove. Therefore, the mass ratio of wax to catalyst is preferably 5:1-50:1.

[0030] In addition, the reaction time is 30-300 min. Considering that too long reaction time will lead to side reactions; too short reaction time will result in insufficient oxidation reaction, so the preferred reaction time is 120-240 min.

[0031] In addition, the hot water temperature for hot water washing can be 50 °C, and it can be washed until the washing liquid is clear.

[0032] Next, in step (2), it can be carried out by the following operations. Put the oxidized wax obtained in step (1) and toluene into a three-necked flask in a predetermined ratio, and ultrasonically oscillate to make it completely dissolve. Add a predetermined amount of acylating agent to the above-mentioned oxidized wax / toluene solution and mix evenly, and heat under reflux for a predetermined time. After the reaction is completed, centrifuge the reaction solution to remove solid substances, and pour the upper layer liquid into a single-necked flask to distill off the solvent at normal pressure to obtain acyl chlorinated wax.

[0033] Among them, the mass ratio of oxidized wax to toluene is 1:5-1:20. Considering the subsequent yield, the preferred mass ratio is 1:5-1:10.

[0034] In addition, the acylating agent used is any one or more of thionyl chloride, phosphorus pentachloride, oxalyl chloride and phosphorus trichloride. The preferred ones are thionyl chloride and / or phosphorus pentachloride. This is because thionyl chloride, as an acyl chlorination reaction reagent, can evaporate the excess thionyl chloride after the reaction, is easier to purify, and has a higher reaction yield. Phosphorus pentachloride has a high acylation rate, can significantly increase the reaction rate, and at the same time lower the reaction temperature, and is easy to handle and has a lower cost after use.

[0035] In addition, the mass ratio of the acylating agent to the oxidized wax is 2:1 to 5:1. Considering that if the ratio is too low, the efficiency will decrease; if the ratio is too high, acylating by-products will be generated. Therefore, the preferred mass ratio is 3:1 to 4:1.

[0036] In addition, the heating reflux temperature is 50 to 80 °C. Considering that too high a temperature will lead to uncontrollable side reactions and cause the solution to turn black, the preferred heating reflux temperature is 50 to 60 °C.

[0037] In addition, the heating reflux time is 30 to 120 min. Considering that if the time is too short, the reaction will be incomplete; if the time is too long, the yield of the acyl chlorinated wax will decrease. Therefore, the preferred heating reflux time is 60 to 90 min.

[0038] In addition, the centrifugal force in the centrifugation process is 200 to 2000 g. Considering that too low a centrifugal force will make it difficult for solid substances to settle, and too high a centrifugal force will damage the required sample, affecting the structure and yield. Therefore, the preferred centrifugal force is 500 to 1000 g.

[0039] Next, in step (3), it can be carried out through the following operations. Disperse the nanocellulose in a predetermined amount of the first organic solvent, add a predetermined amount of triethanolamine and 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by an ice bath and continuously stir. Disperse a predetermined amount of the acyl chlorinated wax obtained in step (3) in the first organic solvent and drop it into the dispersion of the nanocellulose. Carry out an esterification reaction for a predetermined time under a predetermined temperature condition, collect the reaction solution and continuously dialyze it for a predetermined time using a dialysis bag, and finally obtain the nanocellulose-based wax graft through freeze-drying.

[0040] Among them, the nanocellulose used in step (3) is any one or more of nanocrystalline cellulose (CNC), nanofibrillated cellulose (CNF), cationized nanofibrillated cellulose (CCNF), and bacterial cellulose whiskers (BNCW). Preferably, it is any one or more of nanocrystalline cellulose (CNC), nanofibrillated cellulose (CNF), and bacterial cellulose whiskers (BNCW). This is because, compared with cationized nanofibrillated cellulose, the preparation conditions and processes of other nanocelluloses are relatively simple and the cost is relatively low.

[0041] In addition, the first organic solvent and the second organic solvent are any one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and pyridine. Preferably, it is dimethylformamide and / or pyridine. This is because the preferred organic solvents can combine with the generated hydrogen chloride to promote the forward progress of the reaction and can also play a catalytic role. The first organic solvent and the second organic solvent can be the same or different.

[0042] In addition, the mass ratio of nanocellulose: the first organic solvent: triethanolamine: 4-(dimethylamino)pyridine is 1:20:0.05:0.01 to 1:5:0.05:0.05. Considering that while ensuring the forward progress of the subsequent reaction and improving the product yield, the preferred mass ratio is 1:5:0.02:0.01 to 1:10:0.05:0.02.

[0043] In addition, the stirring speed is 100 - 500 rpm. Considering that too low a speed is not conducive to uniform dispersion and the reaction is incomplete; too high a speed will also cause uneven system temperature and promote side reactions. Therefore, the preferred stirring speed is 200 - 400 rpm.

[0044] In addition, the mass ratio of acyl chloride wax to the second organic solvent is 1:5 to 1:20, preferably 1:5 to 1:10. The mass ratio of acyl chloride wax to nanocellulose is 0.5:1 to 5:1.

[0045] In addition, the reaction temperature is 25 - 90 °C. Considering that the esterification reaction is a reversible reaction, in order to increase the yield of the ester, the reaction must be made to proceed as much as possible in the direction favorable for ester formation, so the temperature cannot be too low. Therefore, the preferred reaction temperature is 50 - 90 °C.

[0046] In addition, the reaction time of the esterification reaction is 120 - 360 min. Since when the reaction time is too short, the reaction between the reactants has not been fully carried out and the yield will decrease; when the reaction time is too long, it will lead to the decomposition of the reactants or the occurrence of side reactions. Therefore, the preferred reaction time is 120 - 240 min.

[0047] In addition, the cut-off molecular weight of the dialysis bag used in the present invention is 8 KD.

[0048] In addition, the dialysis time is 2 - 5 days. Considering that sufficient dialysis can remove unreacted small molecules completely. Too short a time results in insufficient removal, and too long a time makes the dialysis bag prone to breakage. Therefore, the preferred dialysis time is 3 - 4 days.

[0049] Finally, in step (4), a predetermined amount of the nanocellulose-based wax graft obtained in step (3) is dispersed in a third organic solution to obtain a nanocellulose-based wax graft dispersion with a predetermined concentration, which is the protective agent of the present invention.

[0050] Among them, the third organic solvent is any one or more of acetone, ethanol, methanol, dichloromethane, benzene, and toluene. Preferably, the third organic solvent is acetone and / or ethanol. This is because, compared with other solvents, acetone and ethanol have good volatility, less harm to the human body, and at the same time, the dispersions prepared in these two solvents are more uniform, increasing storage stability and improving the coating appearance.

[0051] Among them, the mass concentration of the nanocellulose-based wax graft dispersion is 2-15%, preferably 2-5%. The dispersion within this concentration range can be evenly coated on the surface of iron articles, facilitating the penetration and film formation of the sealing solution, and the operation is convenient.

[0052] The sealing agent obtained by the above method is coated on the surface of the iron article to be sealed. After the organic solution volatilizes, a dense sealing film will be formed.

[0053] Therefore, the present invention is particularly suitable for the protection of fragile iron cultural relics. Among them, the iron cultural relics can be unearthed iron cultural relics, preferably unearthed iron pieces and iron nails.

[0054] The technical solution of the present invention will be described in more detail below through Examples 1-9.

[0055] First, prepare 18 unearthed iron pieces with basically the same size and corrosion degree to simulate fragile iron cultural relics for standby. Secondly, the operations of each example are carried out according to the following records.

[0056] Example 1

[0057] (1) Add 100 g of dimethyl silicone oil and 10 g of polyethylene wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C, after stabilizing for 30 min, add 0.2 g of stannous octoate, turn on the air pump, after reacting for 120 min, turn off the air pump, stop heating, pour out the mixture in the four-necked flask, and filter the product by suction after cooling to obtain a crude product, and wash it with hot water to obtain oxidized polyethylene wax.

[0058] (2) Put 5 g of the obtained oxidized polyethylene wax and 30 g of toluene into a three-necked flask, and ultrasonically oscillate to completely dissolve it. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly, and heat and reflux at 50 °C for 30 min. After the reaction is completed, centrifuge the reaction solution at a speed of 500 g to remove solid substances, pour the upper layer liquid into a single-necked flask, and distill off the solvent at normal pressure to obtain acyl chloride polyethylene wax.

[0059] (3) Disperse 5 g of nanocrystalline cellulose in 50 g of dimethylformamide, add 0.25 g of triethanolamine and 0.05 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 200 rpm. Disperse 5 g of acyl chloride polyethylene wax in 50 g of dimethylformamide, and drop it into the nanocellulose dispersion. Carry out an esterification reaction at 50 °C for 120 min, collect the reaction solution and continuously dialyze it with a dialysis bag for 3 days, and finally obtain nanocrystalline cellulose-based polyethylene wax graft by freeze-drying.

[0060] (4) Disperse the obtained nano-crystalline cellulose-based polyethylene wax grafted product into acetone to obtain a nano-crystalline cellulose-based polyethylene wax grafted product dispersion with a mass concentration of 2%, which is used as the sealant in Example 1.

[0061] Example 2

[0062] (1) Add 100 g of dimethyl silicone oil and 10 g of microcrystalline wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 80 °C for the reaction, and after stabilizing for 60 min, add 0.5 g of stannous octoate. Turn on the air pump, and after reacting for 240 min, turn off the air pump and stop heating. Pour out the mixture in the four-necked flask, and after the product cools, filter it by suction to obtain the crude product, and wash it with hot water to obtain oxidized microcrystalline wax.

[0063] (2) Put 5 g of the obtained oxidized microcrystalline wax and 30 g of toluene into a three-necked flask, and ultrasonically vibrate to completely dissolve it. Add 15 g of phosphorus pentachloride to the oxidized wax / toluene solution and mix evenly, and heat and reflux at 60 °C for 90 min. After the reaction is completed, centrifuge the reaction solution at a speed of 800 g to remove the solid matter, pour the upper layer liquid into a single-necked flask, and distill off the solvent at normal pressure to obtain acyl chloride microcrystalline wax.

[0064] (3) Disperse 5 g of nano-crystalline cellulose in 50 g of dimethylformamide, add 0.20 g of triethanolamine and 0.10 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 300 rpm. Disperse 5 g of acyl chloride microcrystalline wax in 50 g of dimethylformamide and drop it into the dispersion of nano-cellulose, and carry out an esterification reaction at 80 °C for 120 min. Collect the reaction solution and continuously dialyze it with a dialysis bag for 3 days, and finally obtain the nano-crystalline cellulose-based microcrystalline wax grafted product by freeze-drying.

[0065] (4) Disperse the obtained nano-crystalline cellulose-based microcrystalline wax grafted product into acetone to obtain a nano-crystalline cellulose-based microcrystalline wax grafted product dispersion with a mass concentration of 2%, which is used as the sealant in Example 2.

[0066] Example 3

[0067] (1) Add 100 g of dimethyl silicone oil and 10 g of white beeswax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C for the reaction, and after stabilizing for 30 min, add 0.2 g of potassium permanganate. Turn on the air pump, and after reacting for 240 min, turn off the air pump and stop heating. Pour out the mixture in the four-necked flask, and after the product cools, filter it by suction to obtain the crude product, and wash it with hot water to obtain oxidized beeswax.

[0068] (2) Put the obtained 5 g of oxidized beeswax and 30 g of toluene into a three-necked flask, and ultrasonically oscillate to completely dissolve them. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly, and heat under reflux at 60 °C for 30 min. After the reaction is completed, centrifuge the reaction solution at a speed of 600 g to remove solid substances, pour the upper layer liquid into a single-necked flask, and distill off the solvent under normal pressure to obtain acyl chloride beeswax.

[0069] (3) Disperse 5 g of nanocrystalline cellulose in 50 g of dimethylformamide, add 0.20 g of triethanolamine and 0.10 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 200 rpm. Disperse 5 g of acyl chloride beeswax in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose, and carry out an esterification reaction at 60 °C for 240 min. Collect the reaction solution and continuously dialyze it for 3 days using a dialysis bag, and finally obtain nanocrystalline cellulose-based beeswax graft by freeze-drying.

[0070] (4) Disperse the obtained nanocrystalline cellulose-based beeswax graft into acetone to obtain a nanocrystalline cellulose-based beeswax graft dispersion with a mass concentration of 2%, which is used as the protective agent in Example 3.

[0071] Example 4

[0072] (1) Put 100 g of dimethyl silicone oil and 10 g of polyethylene wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C for the reaction, and after stabilizing for 30 min, add 0.2 g of stannous octoate. Turn on the air pump, turn off the air pump after reacting for 120 min, stop heating, pour out the mixture in the four-necked flask, and filter the product by suction after cooling to obtain a crude product, and wash it with hot water to obtain oxidized polyethylene wax.

[0073] (2) Put the obtained 5 g of oxidized polyethylene wax and 30 g of toluene into a three-necked flask, and ultrasonically oscillate to completely dissolve them. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly, and heat under reflux at 50 °C for 30 min. After the reaction is completed, centrifuge the reaction solution at a speed of 500 g to remove solid substances, pour the upper layer liquid into a single-necked flask, and distill off the solvent under normal pressure to obtain acyl chloride polyethylene wax.

[0074] (3) Disperse 5 g of nanofibrillated cellulose in 50 g of dimethylformamide, add 0.25 g of triethanolamine and 0.05 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 200 rpm. Disperse 5 g of chlorinated polyethylene wax in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose. Carry out an esterification reaction at 50 °C for 120 min, collect the reaction solution and continuously dialyze it with a dialysis bag for 3 days, and finally obtain nanofibrillated cellulose-based polyethylene wax grafted product by freeze-drying.

[0075] (4) Disperse the obtained nanofibrillated cellulose-based polyethylene wax grafted product in absolute ethanol to obtain a 2% (mass concentration) nanofibrillated cellulose-based polyethylene wax grafted product dispersion, which is used as the sealer in Example 4.

[0076] Example 5

[0077] (1) Add 100 g of dimethyl silicone oil and 10 g of microcrystalline wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 80 °C, and after stabilizing for 60 min, add 0.5 g of stannous octoate. Turn on the air pump, and after reacting for 240 min, turn off the air pump and stop heating. Pour out the mixture in the four-necked flask, and after the product cools, filter it by suction to obtain the crude product, and wash it with hot water to obtain oxidized microcrystalline wax.

[0078] (2) Put 5 g of the obtained oxidized microcrystalline wax and 30 g of toluene into a three-necked flask, and ultrasonically oscillate to completely dissolve it. Add 15 g of phosphorus pentachloride to the oxidized wax / toluene solution and mix evenly, and heat and reflux at 60 °C for 90 min. After the reaction is completed, centrifuge the reaction solution at a speed of 800 g to remove the solid matter, pour the upper layer liquid into a single-necked flask and distill off the solvent at normal pressure to obtain chlorinated microcrystalline wax.

[0079] (3) Disperse 5 g of nanofibrillated cellulose in 50 g of dimethylformamide, add 0.20 g of triethanolamine and 0.10 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 300 rpm. Disperse 5 g of chlorinated microcrystalline wax in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose. Carry out an esterification reaction at 80 °C for 240 min, collect the reaction solution and continuously dialyze it with a dialysis bag for 3 days, and finally obtain nanofibrillated cellulose-based microcrystalline wax grafted product by freeze-drying.

[0080] (4) Disperse the obtained nanofibrillated cellulose-based microcrystalline wax grafted product in absolute ethanol to obtain a 2% (mass concentration) nanofibrillated cellulose-based microcrystalline wax grafted product dispersion, which is used as the sealer in Example 5.

[0081] Example 6

[0082] (1) Add 100 g of dimethyl silicone oil and 10 g of white beeswax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C for the reaction, after stabilizing for 30 min, add 0.2 g of potassium permanganate, turn on the air pump, after reacting for 240 min, turn off the air pump, stop heating, pour out the mixture in the four-necked flask, and after the product cools, filter it by suction to obtain the crude product, and obtain oxidized beeswax after washing with hot water.

[0083] (2) Put 5 g of the obtained oxidized beeswax and 30 g of toluene into a three-necked flask, and ultrasonically oscillate to make it completely dissolve. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly, and heat and reflux at 60 °C for 30 min. After the reaction is completed, centrifuge the reaction solution at a speed of 600 g to remove the solid matter, pour the upper layer liquid into a single-necked flask, and distill off the solvent at normal pressure to obtain acyl chlorinated beeswax.

[0084] (3) Disperse 5 g of nanofibrillated cellulose in 50 g of dimethylformamide, add 0.20 g of triethanolamine and 0.10 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 200 rpm. Disperse 5 g of acyl chlorinated beeswax in 50 g of dimethylformamide, and drop it into the dispersion of nanofibrillated cellulose, and carry out an esterification reaction at 60 °C for 240 min. Collect the reaction solution and continuously dialyze it with a dialysis bag for 3 days, and finally obtain nanofibrillated cellulose-based beeswax grafted product by freeze-drying.

[0085] (4) Disperse the obtained nanofibrillated cellulose-based beeswax grafted product in absolute ethanol to obtain a nanofibrillated cellulose-based beeswax grafted product dispersion with a mass concentration of 2%, which is used as the protective agent in Example 6.

[0086] Example 7

[0087] (1) Add 100 g of dimethyl silicone oil and 10 g of polyethylene wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 80 °C for the reaction, after stabilizing for 60 min, add 0.2 g of stannous octoate, turn on the air pump, after reacting for 240 min, turn off the air pump, stop heating, pour out the mixture in the four-necked flask, and after the product cools, filter it by suction to obtain the crude product, and obtain oxidized polyethylene wax after washing with hot water.

[0088] (2) Put the obtained 5 g of oxidized polyethylene wax and 30 g of toluene into a three-necked flask, and ultrasonically vibrate to completely dissolve it. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly, and heat under reflux at 60 °C for 90 min. After the reaction is completed, centrifuge the reaction solution at a speed of 500 g to remove solid substances, pour the upper layer liquid into a single-necked flask, and distill off the solvent at normal pressure to obtain acylated polyethylene wax.

[0089] (3) Disperse 5 g of bacterial cellulose whiskers in 50 g of dimethylformamide, add 0.10 g of triethanolamine and 0.05 g of 4-(dimethylamino)pyridine, then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 400 rpm. Disperse 5 g of acylated polyethylene wax in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose. Carry out an esterification reaction at 80 °C for 240 min, collect the reaction solution and continuously dialyze it for 3 days using a dialysis bag, and finally obtain a bacterial cellulose-based polyethylene wax graft by freeze-drying.

[0090] (4) Disperse the obtained bacterial cellulose-based polyethylene wax graft into acetone to obtain a dispersion of bacterial cellulose-based polyethylene wax graft with a mass concentration of 2%, which is used as the sealer for Example 7.

[0091] Example 8

[0092] (1) Put 100 g of dimethyl silicone oil and 10 g of microcrystalline wax into a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C for the reaction, and after stabilizing for 30 min, add 0.2 g of stannous octoate. Turn on the air pump, turn off the air pump after reacting for 120 min, stop heating, pour out the mixture in the four-necked flask, and filter the product by suction after cooling to obtain a crude product, and wash it with hot water to obtain oxidized microcrystalline wax.

[0093] (2) Put the obtained 5 g of oxidized microcrystalline wax and 30 g of toluene into a three-necked flask, and ultrasonically vibrate to completely dissolve it. Add 20 g of phosphorus pentoxide to the oxidized wax / toluene solution and mix evenly, and heat under reflux at 50 °C for 90 min. After the reaction is completed, centrifuge the reaction solution at a speed of 500 g to remove solid substances, pour the upper layer liquid into a single-necked flask, and distill off the solvent at normal pressure to obtain acylated microcrystalline wax.

[0094] (3) Disperse 5 g of bacterial cellulose whiskers in 50 g of dimethylformamide, add 0.15 g of triethanolamine and 0.05 g of 4-(dimethylamino)pyridine. Then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 200 rpm. Disperse 5 g of acyl chloride microcrystalline paraffin in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose. Carry out an esterification reaction at 60 °C for 180 min. Collect the reaction solution and continuously dialyze it for 3 days using a dialysis bag. Finally, obtain the bacterial cellulose-based microcrystalline paraffin graft by freeze-drying.

[0095] (4) Disperse the obtained bacterial cellulose-based microcrystalline paraffin graft in acetone to obtain a 2% (by mass) dispersion of the bacterial cellulose-based microcrystalline paraffin graft, which is used as the protective agent in Example 8.

[0096] Example 9

[0097] (1) Add 100 g of dimethyl silicone oil and 10 g of white beeswax to a four-necked flask, stir evenly, and turn on the oil bath to heat and melt the raw materials. Raise the temperature of the oil bath to 60 °C for the reaction. After stabilizing for 30 min, add 0.2 g of potassium permanganate, turn on the air pump. After reacting for 180 min, turn off the air pump and stop heating. Pour out the mixture in the four-necked flask. After the product cools, filter it by suction to obtain the crude product, and wash it with hot water to obtain oxidized beeswax.

[0098] (2) Put 5 g of the obtained oxidized beeswax and 30 g of toluene into a three-necked flask and ultrasonically vibrate to completely dissolve it. Add 15 g of thionyl chloride to the oxidized wax / toluene solution and mix evenly. Heat and reflux at 50 °C for 60 min. After the reaction is completed, centrifuge the reaction solution at a speed of 500 g to remove the solid substances. Pour the upper layer liquid into a single-necked flask and distill off the solvent at normal pressure to obtain acyl chloride beeswax.

[0099] (3) Disperse 5 g of bacterial cellulose whiskers in 50 g of dimethylformamide, add 0.15 g of triethanolamine and 0.10 g of 4-(dimethylamino)pyridine. Then cool the mixture to 0 °C by ice bath and continuously stir at a speed of 400 rpm. Disperse 5 g of acyl chloride beeswax in 50 g of dimethylformamide and drop it into the dispersion of nanocellulose. Carry out an esterification reaction at 80 °C for 120 min. Collect the reaction solution and continuously dialyze it for 3 days using a dialysis bag. Finally, obtain the bacterial cellulose-based beeswax graft by freeze-drying.

[0100] (4) Disperse the obtained bacterial cellulose-based beeswax graft in acetone to obtain a 2% (by mass) dispersion of the bacterial cellulose-based beeswax graft, which is used as the protective agent in Example 9.

[0101] The encapsulants of each embodiment were respectively coated on the prepared unearthed iron pieces. After the organic solution volatilized, it was found that a dense encapsulating film was formed. Considering the influence of the temperature and humidity of the experimental environment each time, for each encapsulation sample of each embodiment, a parallel blank sample was made simultaneously. Before and after the intermittent spray wet-dry aging treatment of each encapsulation sample of each embodiment and its parallel blank sample (i.e., the sample that was only aged without being encapsulated with the encapsulant), the test results were recorded in Table 1 below. Among them, for the aging treatment, each sample was placed at an angle of 15° to the horizontal position, and commercially available tap water was used to spray water mist for 30 min and then stop spraying water mist for 30 min. This was carried out for 360 h, and the surface of the specimen was observed once every 24 h and recorded during this period.

[0102] The detection methods for each test index are as follows:

[0103] Water contact angle: The contact angle between the surface before and after encapsulation and deionized water was measured using a contact angle measuring instrument. Five positions were taken on the surface of each specimen for measurement and the average value was taken.

[0104] Oxygen permeation rate: An oxygen permeability tester was used to measure the oxygen permeation amount of the sample by the isobaric method at 25 °C and 75% relative humidity.

[0105] Water vapor transmission rate: A certain amount of distilled water was poured into a glass bottle, and the bottle mouth was covered with an iron block of 50 mm × 50 mm × 30 mm size, and then the glass edge was sealed with waterproof silicone rubber. The initial weight of the glass bottle assembly was recorded as M0. During the whole experiment, the water level in the bottle was about 20 mm away from the sample. The sample was weighed once every 24 h and the weight change was recorded.

[0106] The water vapor transmission rate (WVTR) was evaluated as the mass of water vapor passing through a unit area per unit time. The calculation formula is: △M is the weight change, g; A is the area exposed to water vapor, m 2 ; t is the time, h.

[0107] After the encapsulant coated on the iron cultural relics formed a film, it could be wiped off with hot water at 60 - 70 degrees. After being wiped off, it could be re-coated, which conforms to the principle of reversibility of cultural relic protection and achieves the purpose of re-treatment.

[0108] Corrosion rate: The change in the mass of the sample before and after aging corrosion was measured as △M, and the corrosion rate v = △M / (A·t) g·m-2·h-1

[0109] A is the area, m 2 ; t is the time, h.

[0110] Corrosion inhibition rate: After aging, the corrosion rate of the protected sample is v1, and the corrosion rate of the blank sample after aging is v2. The corrosion inhibition rate (%) = (v2 - v1) / v2 × 100.

[0111] Color difference value: The colorimetric values (L0, a0, b0) of the specimen surface before treatment and the colorimetric values (L, a, b) after treatment are measured respectively using a color difference meter. Each group of specimens has 3 parallel specimens, and the color difference change value is obtained.

[0112] Glossiness change rate: The glossiness of the sample before and after protection is measured using a glossiness meter as G0 and G respectively. The glossiness change rate (%) is (G0 - G) / G0 × 100.

[0113] Table 1 Detection results of each sample

[0114]

[0115] As can be seen from Table 1, Examples 1 to 9 of the present invention can all form a reversible sealing protective film on the surface of fragile iron cultural relics, providing effective protection for fragile iron cultural relics.

[0116] In summary, according to the technical solution of the present invention, the following technical effects are mainly achieved:

[0117] (1) After the wax is carboxylated by an oxidant and acylated by an acylating reagent, an esterification reaction occurs with nanocellulose to obtain a nanocellulose-based wax graft. The protective agent prepared therefrom has a tight structure, no glare, and good transparency after film formation.

[0118] (2) The wax molecular segments make the graft have good water resistance and good fluidity at higher temperatures, facilitating the removal of the protective agent in the later stage and re-protection.

[0119] (3) Using nanocellulose, the formed film has extremely high oxygen barrier performance.

[0120] (4) By optimizing the process parameters, a protective agent with excellent performance, especially suitable for protecting fragile iron cultural relics, is prepared efficiently and at low cost.

[0121] The above embodiments, especially any "preferred" embodiments, are possible examples of the implementation manners and are only proposed for a clear understanding of the principles of the present invention. Many changes and modifications can be made to the above embodiments without substantially departing from the spirit and principles of the technology described herein. All modifications are intended to be included within the scope of the present disclosure.

[0122] All documents mentioned in this specification are incorporated herein by reference as if each document were fully incorporated herein by reference.

[0123] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the protection scope of the present invention.

Claims

1. A preparation method of a sealing agent, characterized in that, The preparation method of the protective agent comprises the following steps: Step (i): Disperse nanocellulose, triethanolamine, and 4-(dimethylamino)pyridine in a first organic solvent to obtain a nanocellulose dispersion, and disperse acyl chloride wax in a second organic solvent to obtain an acyl chloride wax dispersion; Step (ii): Mix the acyl chloride wax dispersion with the nanocellulose dispersion, and after an esterification reaction, obtain a nanocellulose-based wax graft; and Step (iii): Disperse the nanocellulose-based wax graft in a third organic solvent to obtain the protective agent, wherein the nanocellulose is any one or more of nanocrystalline cellulose, nanofibrillated cellulose, cationized nanofibrillated cellulose, and bacterial cellulose whiskers; the first organic solvent is any one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and pyridine; the second organic solvent is any one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and pyridine; and the third organic solvent is any one or more of acetone, ethanol, methanol, dichloromethane, benzene, and toluene.

2. The preparation method of the coating agent according to claim 1, wherein In step (i), the mass ratio of the nanocellulose, the first organic solvent, the triethanolamine, and the 4-(dimethylamino)pyridine is 1:20:0.05:0.01 to 1:5:0.05:0.05; the mass ratio of the acyl chloride wax to the second organic solvent is 1:5 to 1:20; and the mass ratio of the acyl chloride wax to the nanocellulose is 0.5:1 to 5:

1.

3. The preparation method of the sealer according to claim 2, characterized in that In step (ii), cool the nanocellulose dispersion to 0 °C by ice bath and continuously stir, drop the acyl chloride wax dispersion into the nanocellulose dispersion, carry out the esterification reaction at 25-90 °C for 120-360 min, collect the reaction solution, and dialyze it using a dialysis bag for 2-5 days, and then obtain the nanocellulose-based wax graft by freeze-drying.

4. The preparation method of the encapsulant according to claim 3, characterized in that, The acyl chloride wax is obtained by mixing oxidized wax and toluene in a mass ratio of 1:5 to 1:20, and then adding an acylating agent to carry out an acylation reaction, wherein the acylating agent is any one or more of thionyl chloride, phosphorus pentachloride, oxalyl chloride, and phosphorus trichloride; and the mass ratio of the acylating agent to the oxidized wax is 2:1 to 5:

1.

5. The preparation method of the encapsulant according to claim 4, characterized in that, The acylation reaction is carried out under the condition of heating to reflux at 50-80 °C for 30-120 min.

6. The preparation method of the encapsulant according to claim 4, characterized in that, The oxidized wax is obtained by mixing dimethyl silicone oil and wax in a mass ratio of 20:1 to 2:1, and then carrying out an oxidation reaction on the wax in the presence of a catalyst and air, the wax is any one or more of polyethylene wax, microcrystalline wax, palm wax, beeswax, shellac, and Chinese wax; the catalyst is any one or more of stannous octoate, magnesium stearate, potassium permanganate, and cobalt acetate; 7. The preparation method of the encapsulant according to claim 6, characterized in that, the oxidation reaction is carried out at 60-150 °C for 30-90 min, and the mass ratio of the wax to the catalyst is 5:1 to 50:

1.

8. A sealer, characterized in that, The protective agent is prepared by the preparation method of the protective agent according to any one of claims 1 to 7.

9. A method for protecting iron articles, characterized in that, The protection method of the iron article includes covering the surface of the iron article with the encapsulant described in claim 8.

10. The protection method of the iron article according to claim 9, characterized in that, The iron article is an iron cultural relic.

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