Phosphonated modified chitosan high-temperature slow-release retarder as well as preparation method and application thereof
By phosphating, carboxylation and hydrophobizing chitosan, a phosphating modified chitosan high-temperature sustained release retarder was prepared, which solved the problems of poor stability of existing retarders at high temperatures and unstable retarding effects, and achieved a durable and controllable retarding effect under high temperature environments.
Patent Information
- Application Number
- CN202411841294.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-04-15
AI Technical Summary
The existing retarder has poor stability at high temperatures, unstable retarding effect, and difficult to control the release rate, resulting in an impact on the construction operation time, and the concrete is prone to early curing, affecting the construction quality.
By phosphating and carboxylation of modified chitosan, the multidentate chelation site is increased, its calcium ion chelation ability is improved at high temperature, and the stability is improved through hydrophobic modification, a phosphating modified chitosan high-temperature sustained release delaying agent is prepared.
Under high temperature environment, phosphonic modified chitosan high-temperature sustained release retarder can stably capture calcium ions, significantly delay the hydration process of cement, ensure the durability and controllability of the retarding effect, and improve construction quality and project progress.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of building admixtures, in particular to a phosphonated modified chitosan high temperature slow-release retarder and a preparation method and application thereof. Background Art
[0002] In the field of concrete construction, especially in large-volume and high-temperature construction, the use of retarders has become an important means to ensure concrete performance and construction quality. In the prior art, carboxylates, organic phosphonic acids and polymer modified materials are usually used, which can achieve a retarding effect by complexing calcium ions or inhibiting hydration reactions. However, many retarders will decompose or chemically fail at high temperatures, resulting in uneven release of retarders, thereby causing problems such as unstable control effects. In particular, when the retarder reacts with calcium ions in cement, changes in temperature will aggravate the decomposition of the retarder, making the hydration reaction time difficult to predict, affecting the progress and quality of the project. At the same time, traditional retarders are often difficult to control the release rate under high temperature conditions, resulting in unstable retarding effects during construction, and prone to problems such as early inactivation, insufficient retarding time or excessive retarding.
[0003] These problems are mainly attributed to the single action mechanism of existing retarders, which is to delay the hydration reaction by directly complexing hydrated calcium ions or surface adsorption. Although this method can achieve a good retarding effect under normal temperature, in the application of high temperature or large volume concrete, the hydration reaction is accelerated, the retarder molecule activity quickly fails, and it is difficult to achieve a slow and stable release, which affects the construction operation time, and the concrete is easy to solidify early, which in turn affects the construction quality. Summary of the invention
[0004] The present invention aims to solve the problems of poor stability and inability to continuously release the retarding effect of existing retarders when used at high temperatures, and provides a method for preparing a phosphonated modified chitosan high temperature slow-release retarder, comprising the following steps: S100, chitosan is modified by using phosphonyl chloride and triethylamine to obtain phosphonated chitosan; The molar ratio of the phosphonyl chloride to chitosan is (0.6-1.8):1; it is a phosphonation reagent used to introduce phosphonic acid groups into chitosan; S200, adding acetic anhydride and an alkaline catalyst to the obtained phosphonated chitosan, adjusting the pH value to 7-8 until the reaction is complete, extracting, centrifuging and drying to obtain carboxylated chitosan; Wherein, the molar ratio of the amount of acetic anhydride to the amount of chitosan is (1.5-2.5):1; used for further carboxylation modification of phosphonated chitosan; S300, preparing a solution of the obtained carboxylated chitosan, adding long-chain acyl chloride and triethylamine, washing, centrifuging and drying after sufficient reaction, and finally obtaining the phosphonated modified chitosan high temperature slow-release retarder; The molar ratio of the long-chain acyl chloride to the chitosan is (0.1-1):1, which is used for hydrophobic modification; In the S100 and S200, the molar ratio of triethylamine to chitosan is (0.9-1.5):1, and triethylamine is an acid neutralizer to ensure stable reaction conditions.
[0005] In the design concept of the technical solution of the present invention, chitosan is modified into phosphonated chitosan to improve its calcium ion chelating ability, and carboxyl groups are further introduced to enhance the multi-dentate coordination between the molecule and calcium ions for hydrophobic modification, thereby improving the stability and sustained release effect of chitosan in a high temperature environment. The resulting product has the characteristic of maintaining long-term slow setting in a high temperature environment.
[0006] On the basis of the above technical solution, further, S100 includes the following steps: S110, placing chitosan in an organic solvent and stirring to dissolve at 65-75° C.; S120, under nitrogen protection, slowly drop a quantitative amount of phosphonyl chloride into the solution, and at the same time add a quantitative amount of triethylamine, and continue stirring at 70-90° C. until the reaction is fully completed to ensure that the phosphonic acid group is fully bound to the amino site of chitosan; during this process, a quantitative amount of triethylamine is added to neutralize the generated hydrogen chloride to prevent excessive reaction; S130, after the reaction is completed, the solution is cooled and methanol is added to precipitate the product, which is then centrifuged and washed with deionized water to obtain phosphonated chitosan.
[0007] On the basis of the above technical solution, further, S200 includes the following steps: S210, dissolving the obtained phosphonated chitosan in an organic solvent, slowly adding acetic anhydride to the solution, and adding a small amount of alkaline catalyst, adjusting the pH value to 7-8, and stirring at 60-80° C. until the reaction is complete, so that the carboxyl group is introduced into the chitosan molecular structure; S220, cooling the reaction product, extracting it with an organic solvent, centrifuging it and drying it to obtain carboxylated chitosan.
[0008] On the basis of the above technical solution, further, S300 includes the following steps: S310, dissolving the obtained carboxylated chitosan in an organic solvent, slowly adding long-chain acyl chloride and dripping triethylamine under nitrogen protection to neutralize the generated byproduct hydrogen chloride, and fully reacting at 60-80° C.; S320, cooling the reaction product, washing it with dichloromethane, centrifuging it and drying it, and finally obtaining the phosphonated modified chitosan high temperature sustained-release retarder.
[0009] On the basis of the above technical solution, further, 1. the chitosan is a natural polymer basic skeleton, its molecular weight is 300-500 kDa, and its deacetylation degree is 80%-90%.
[0010] On the basis of the above technical solution, further, the alkaline catalyst is triethylamine, and the molar ratio of triethylamine to chitosan is (0.9~1.5):1.
[0011] On the basis of the above technical solution, further, the long-chain acyl chloride is one of octanoyl chloride, decanoyl chloride and dodecanoyl chloride.
[0012] On the basis of the above technical solution, further, the organic solvent is one of dichloromethane and dimethyl sulfoxide.
[0013] The present invention also provides a phosphonated modified chitosan high temperature sustained-release retarder prepared by any of the above methods for preparing the phosphonated modified chitosan high temperature sustained-release retarder.
[0014] The present invention also provides a use of a phosphonated modified chitosan high temperature slow-release retarder prepared by any of the above methods for preparing the phosphonated modified chitosan high temperature slow-release retarder or the phosphonated modified chitosan high temperature slow-release retarder according to claim 9 in concrete construction.
[0015] The technical solution of the present invention has the following principles and beneficial effects: By multiple modifications of chitosan molecules with phosphonic acid and carboxyl groups, and the addition of the amino groups of chitosan itself, the chitosan molecules have multi-dentate chelating sites, which can form more stable chelates with calcium ions. Even under high temperature conditions, they can stably capture calcium ions, significantly delay the hydration process of cement, and ensure excellent retarding effects under different conditions.
[0016] With chitosan as the basic structure, the retarder has good high temperature stability and is not easy to degrade or fail in high temperature environment. At the same time, the introduced hydrophobic groups (such as octanoyl) further enhance the heat resistance of the molecule, reduce the rapid dissolution in high temperature environment, prolong the action time of the retarder, and ensure the continuous retarding effect.
[0017] The phosphonated modified chitosan high temperature slow-release retarder provided by the present invention has the following advantages: The microporous structure of chitosan allows it to absorb water and slowly dissolve in cement paste. The active groups (such as phosphonic acid groups) therein are slowly released, continuously chelating calcium ions, and prolonging the action time of the retarder. At the same time, chitosan is a high molecular weight polymer chain structure, and the gradual dissociation and diffusion of the molecular chains in the cement paste bring about a natural slow-release effect. In addition, the dispersibility of chitosan is improved after modification, and it can be evenly distributed in the cement paste, and can also play an effective role in a high temperature environment, achieving a long-lasting slow-release effect.
[0018] The phosphonated modified chitosan high temperature slow-release retarder provided by the invention realizes the effective slow-setting of concrete in a high temperature construction environment, meets the special requirements of concrete construction in a high temperature environment, and has important practical application value. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0020] The present invention provides the following embodiments of the phosphonated modified chitosan high temperature slow-release retarder: Example 1 Dissolve 80.5 g of 400 kDa chitosan in 200 mL of dimethyl sulfoxide (DMSO) and stir to dissolve at 70 ° C. Under nitrogen protection, slowly add 92 g of phosphonyl chloride (the molar ratio of phosphonyl chloride to chitosan is about 1.2:1) to the solution, and add 60.7 g of triethylamine (the molar ratio of triethylamine to chitosan is about 1.2:1) to neutralize hydrogen chloride. The mixture is reacted at 80 ° C for 3 hours, cooled, and the product is precipitated with methanol, and centrifuged and washed to obtain phosphonated chitosan.
[0021] Dissolve the phosphonated chitosan in 200 mL of dimethyl sulfoxide (DMSO), add 102.1 g of acetic anhydride (the molar ratio of acetic anhydride to chitosan is about 2:1) and a small amount of triethylamine 60.7 g, adjust the pH value to 7-8, stir and react at 70°C for 3 hours, cool and extract with dichloromethane, and centrifuge to obtain carboxylated chitosan.
[0022] The carboxylated chitosan was dissolved in 200 mL of dimethyl sulfoxide (DMSO), and 40.7 g of octanoyl chloride (the molar ratio of octanoyl chloride to chitosan was about 0.5:1) and 60.7 g of triethylamine were slowly added under nitrogen protection. The mixture was reacted at 70°C for 4 hours. After cooling, it was washed with dichloromethane and centrifuged to obtain a phosphonated modified chitosan high temperature sustained-release retarder.
[0023] Example 2 Reducing the dosage of phosphonyl chloride The difference from Example 1 is that the dosage of phosphonyl chloride is 46 g (the molar ratio of phosphonyl chloride to chitosan is about 0.6:1), and other conditions remain unchanged, and finally a phosphonated modified chitosan high temperature slow-release retarder is obtained.
[0024] Example 3 Reducing the Molecular Weight of Chitosan The difference from Example 1 is that 80.5 g of 300 kDa chitosan is used, and other conditions remain unchanged, and finally a phosphonated modified chitosan high temperature slow-release retarder is obtained.
[0025] Example 4: Reducing the dosage of the acid neutralizer The difference from Example 1 is that the amount of triethylamine added is 45.5 g (the molar ratio of triethylamine to chitosan is about 0.9:1), and the amount of acetic anhydride added in the second step is 204.2 g (the molar ratio of acetic anhydride to chitosan is about 4:1), and the amount of octanoyl chloride added in the third step is 81.3 g (the molar ratio of octanoyl chloride to chitosan is about 1:1), and other conditions remain unchanged, and finally a phosphonated modified chitosan high temperature slow-release retarder is obtained.
[0026] Example 5: Reducing the dosage of acetic anhydride Similar to Example 1, except that the amount of acetic anhydride added was 76.6 g (the molar ratio of acetic anhydride to chitosan was about 1.5:1), and other conditions remained unchanged, and finally a phosphonated modified chitosan high temperature slow-release retarder was obtained.
[0027] Example 6 Increasing the dosage of octanoyl chloride Similar to Example 1, except that the addition amount of octanoyl chloride is 81.3 g (the molar ratio of octanoyl chloride to chitosan is about 1:1), and other conditions remain unchanged, and finally a phosphonated modified chitosan high temperature slow-release retarder is obtained.
[0028] Mortar test verification The mortar test was conducted on the five examples of products in a 55 degree environment. Before mixing, the mortar raw materials were heated to 55 degrees Celsius; after mixing, the mortar was placed in a 55 degree Celsius oven for insulation, and the initial setting time test was conducted every 10 minutes from the third hour.
[0029] The formula of mortar is cement C: 400g, sand S: 800g, water W: 170g, admixture A: 2% of the total mass of the adhesive. The admixture used is Point-S pure water-reducing admixture (without slump retention or retarding effect) produced by Kezhijie New Materials Group Co., Ltd.
[0030] Wherein, comparative example 1 is a blank control; Comparative Example 2 is a comparison of adding organic phosphine HEDP as a retarder in mortar.
[0031] Comparative Example 3 is based on Example 1, except that the phosphonated chitosan is replaced with 400 kDa chitosan, and other conditions remain unchanged.
[0032] Comparative Example 4 is based on Example 1, except that acetic anhydride is not added and other conditions remain unchanged.
[0033] Comparative Example 5 is based on Example 1, except that octanoyl chloride is not added and other conditions remain unchanged.
[0034] Table 1 Fluidity and setting time of different retarders at high temperature
[0035] The above results show that the phosphonated modified chitosan high temperature slow-release retarder prepared by the present invention was evaluated for performance in a high temperature environment of 55 degrees through a mortar test experiment. The experimental results clearly show that compared with the organic phosphine HEDP retarder and other comparative samples, the phosphonated modified chitosan high temperature slow-release retarder provided by the present invention exhibits excellent slow-setting performance, and can significantly prolong the initial setting time of the mortar under high temperature conditions with stable release.
[0036] The phosphonated modified chitosan high temperature slow-release retarder provided by the present invention has a high efficiency chelating force for calcium ions by implementing combined modification of phosphonation, carboxylation and hydrophobization on chitosan, thereby solving the stability problem of chitosan at high temperature and ensuring that the chelating function is not affected by the environment.
[0037] The phosphonated modified chitosan high temperature slow-release retarder provided by the present invention can maintain stability and slow-release characteristics at high temperatures, is suitable for fields such as high-temperature buildings and special cement products, and solves the problem of degradation and failure of ordinary retarders at high temperatures. The introduction of multiple chelating sites ensures that it has the ability to efficiently capture and slow-release calcium ions, making its slow-setting effect during the construction process more durable and controllable, meeting the actual demand for retarders in engineering applications. In addition, based on chitosan, it has the advantages of being environmentally friendly and degradable, and meets the requirements of modern green buildings and environmentally friendly engineering materials.
[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a phosphonated modified chitosan high temperature sustained-release retarder, characterized in that: The following steps are involved: S100, chitosan is modified by using phosphonyl chloride and triethylamine to obtain phosphonated chitosan; Wherein, the molar ratio of the phosphonyl chloride to the chitosan is (0.6-1.8): 1; S200, adding acetic anhydride and an alkaline catalyst to the obtained phosphonated chitosan, adjusting the pH value to 7-8 until the reaction is complete, extracting, centrifuging and drying to obtain carboxylated chitosan; Wherein, the molar ratio of the amount of acetic anhydride to the amount of chitosan is (1.5-2.5): 1; S300, preparing a solution of the obtained carboxylated chitosan, adding long-chain acyl chloride and triethylamine, washing, centrifuging and drying after sufficient reaction, and finally obtaining the phosphonated modified chitosan high temperature slow-release retarder; The molar ratio of the long-chain acyl chloride to the chitosan is (0.1-1):1; In the S100 and S200, the molar ratio of triethylamine to chitosan is (0.9-1.5):
1.
2. The method for preparing the phosphonated chitosan high temperature sustained-release retarder according to claim 1, characterized in that: S100 includes the following steps: S110, placing chitosan in an organic solvent and stirring to dissolve at 65-75° C.; S120, under nitrogen protection, slowly drop a quantitative amount of phosphonyl chloride into the solution, and simultaneously add a quantitative amount of triethylamine, and continue stirring at 70-90° C. until the reaction is fully reacted; S130, after the reaction is completed, the solution is cooled and methanol is added to precipitate the product, which is then centrifuged and washed with deionized water to obtain phosphonated chitosan.
3. The method for preparing the phosphonated modified chitosan high temperature sustained-release retarder according to claim 1, characterized in that: S200 includes the following steps: S210, dissolving the obtained phosphonated chitosan in an organic solvent, slowly adding acetic anhydride to the solution, adding a small amount of alkaline catalyst, adjusting the pH value to 7-8, and stirring at 60-80° C. until the reaction is complete; S220, cooling the reaction product, extracting it with an organic solvent, centrifuging it and drying it to obtain carboxylated chitosan.
4. The method for preparing the phosphonated chitosan high temperature slow-release retarder according to claim 1, characterized in that: S300 includes the following steps: S310, dissolving the obtained carboxylated chitosan in an organic solvent, slowly adding long-chain acyl chloride and dripping triethylamine under nitrogen protection, and fully reacting at 60-80° C.; S320, cooling the reaction product, washing it with dichloromethane, centrifuging it and drying it, and finally obtaining the phosphonated modified chitosan high temperature sustained-release retarder.
5. The method for preparing the phosphonated chitosan high temperature sustained-release retarder according to claim 1, characterized in that: The molecular weight of the chitosan is 300-500 kDa, and the degree of deacetylation is 80%-90%.
6. The method for preparing the phosphonated modified chitosan high temperature sustained-release retarder according to claim 1, characterized in that: The alkaline catalyst is triethylamine, and the molar ratio of triethylamine to chitosan is (0.9-1.5):
1.
7. The method for preparing the phosphonated modified chitosan high temperature sustained-release retarder according to claim 1, characterized in that: The long-chain acyl chloride is one of octanoyl chloride, decanoyl chloride and dodecanoyl chloride.
8. The method for preparing the phosphonated chitosan high temperature sustained-release retarder according to any one of claims 2 to 4, characterized in that: The organic solvent is one of dichloromethane and dimethyl sulfoxide.
9. A phosphonated modified chitosan high temperature sustained-release retarder prepared by the method for preparing a phosphonated modified chitosan high temperature sustained-release retarder according to any one of claims 1 to 8.
10. Use of the phosphonated modified chitosan high temperature slow-release retarder prepared by the preparation method of the phosphonated modified chitosan high temperature slow-release retarder according to any one of claims 1 to 8 or the phosphonated modified chitosan high temperature slow-release retarder according to claim 9 in concrete construction.