Preparation method and application of HEDP-PEG high-temperature-resistant slow-release retarder

Abstract

The invention relates to the technical field of building admixtures, in particular to a preparation method and application of an HEDP-PEG high-temperature-resistant slow-release retarder. Wherein the retarder is synthesized by using a raw material PEG, a cross-linking agent, an anhydrous organic solvent and organic phosphine molecules HEDP. According to the prepared high-temperature-resistant slow-release retarder, a PEG molecular structure is introduced into an HEDP molecular structure, so that the retarding effect is good, slow release is achieved, and the molecular stability, heat resistance and calcium ion capturing capacity are improved through a cross-linking reaction. The synthesis route is simple and environment-friendly, conditions are mild, energy consumption is low, raw materials are common, cost is reasonable, and industrialization prospects are good. Mortar tests prove that the HEDP-PEG high-temperature-resistant slow-release retarder provided by the invention can remarkably prolong the initial setting time of mortar at high temperature and is stable in release, and the defects of a common retarder in a high-temperature environment are effectively overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of building admixtures, and in particular to a preparation method and application of a HEDP-PEG high-temperature resistant slow-release retarder. Background Art

[0002] In concrete construction, especially for large-volume construction and high-temperature environments, retarders are crucial for ensuring concrete performance and construction quality. Currently, commonly used retarders include carboxylates, organophosphonic acids, and polymer-modified materials. These primarily achieve their retarding effect by complexing calcium ions or inhibiting hydration reactions. However, existing retarders present numerous challenges.

[0003] Many retarders decompose or chemically lose effectiveness at high temperatures, resulting in uneven release and unstable control. When reacting with calcium ions in cement, temperature fluctuations exacerbate their decomposition, making hydration reaction time unpredictable and impacting project progress and quality. Traditional retarders are difficult to control their release rate at high temperatures, leading to premature deactivation and insufficient or excessive retarding time.

[0004] These issues stem from the single mechanism of action of existing retarders, which delay the hydration reaction by directly complexing hydrated calcium ions or through surface adsorption. While they have a certain retarding effect at room temperature, at high temperatures or in large concrete volumes, the hydration reaction accelerates, causing the retarder molecules to lose their activity quickly and failing to achieve a slow and stable release. This results in limited construction time, premature concrete curing, and poor construction quality. Summary of the Invention

[0005] To solve the above problems, the present invention provides a HEDP-PEG high temperature resistant slow-release retarder, the structural formula of which is: ; Among them, PEG is polyethylene glycol, its molecular weight is 2000-5000, and its structural formula is: , n=45~110; HEDP is an organic phosphine molecule with the structural formula:

[0006] Wherein, R is a hydrocarbon group.

[0007] The present invention provides a method for preparing a HEDP-PEG high-temperature resistant slow-release retarder, comprising the following steps: S100, in a reaction vessel, dissolving a predetermined amount of PEG in a sufficient amount of anhydrous organic solvent, adding a catalyst, and slowly adding a dibasic acid anhydride; stirring while adding, reacting at 30-50° C. for 4-6 hours to generate a PEG-dibasic acid anhydride cross-linked intermediate; S200, adding a certain amount of HEDP to the reaction system, maintaining the reaction temperature at 30-50°C, and continuously stirring for 8-12 hours to form a stable HEDP-PEG cross-linked network; S300, removing the reaction solvent, and washing the resulting product in anhydrous ethanol, stirring the mixture sufficiently to dissolve the residual anhydrous organic solvent and small molecular impurities, and drying the washed product in a vacuum drying oven to obtain a HEDP-PEG high-temperature resistant sustained-release retarder.

[0008] On the basis of the above technical solution, further, according to the molar ratio, HEDP: dibasic acid anhydride: PEG: catalyst = 1:1: (0.5-1): (0.005-0.01).

[0009] On the basis of the above technical solution, further, the molecular weight of the PEG is 2000-5000, and its general structural formula is: , n=45~110; The HEDP is an organic phosphine molecule, and its simplified structural formula is: .

[0010] On the basis of the above technical solution, further, the PEG-diacid anhydride cross-linked intermediate has a simplified structural formula: PPEG-OC(O)-R-COOH.

[0011] On the basis of the above technical solution, further, the cross-linking agent is a dibasic acid anhydride, and its simplified structural formula is as follows: RC(O)-OC(O)-R'.

[0012] Preferably, the dibasic acid anhydride can be selected from maleic anhydride and glutaric anhydride.

[0013] On the basis of the above technical solution, further, the cross-linking agent is one of glutaric anhydride, citric acid, maleic anhydride, and succinic anhydride.

[0014] On the basis of the above technical solution, further, the catalyst is a weak acid catalyst, and the usage amount is 0.5% to 1% relative to the molar amount of dibasic acid anhydride and HEDP.

[0015] On the basis of the above technical solution, further, the catalyst is benzoic acid.

[0016] On the basis of the above technical solution, further, the anhydrous organic solvent is dimethylformamide or dimethyl sulfoxide.

[0017] The present invention also provides a use of any of the above-mentioned HEDP-PEG high-temperature resistant slow-release retarder in concrete construction.

[0018] The technical solution of the present invention has the following principles and beneficial effects: The technical solution of this invention innovatively incorporates the PEG molecular structure into the HEDP molecular structure, creating a unique HEDP-PEG high-temperature-resistant, slow-release retarder. This molecular design not only retains HEDP's excellent calcium chelating properties, thereby ensuring excellent retarding effect in high-temperature environments, but also leverages the temperature-sensitive properties of PEG to impart intelligent temperature responsiveness to the retarder. As the temperature changes, the retarder can precisely control the release of its retarding effect, effectively avoiding the uneven release problem associated with conventional retarders at high temperatures due to their poor stability, significantly improving the controllability and stability of the retarding performance.

[0019] The introduction of the PEG molecular structure also significantly improves the retarder's dispersibility, ensuring its uniform distribution within the concrete system and further enhancing the consistency of the retarding effect. Furthermore, the 3D network formed by cross-linking the two molecules acts like a solid "skeleton," greatly enhancing the overall stability of the molecule and improving the "wrapping" of the HEDP molecules by PEG. This 3D network, combined with PEG's temperature sensitivity, allows the retarder's release to be controlled with temperature changes. The network structure facilitates the capture of calcium ions, enhancing the retarder's performance in high-temperature environments.

[0020] In the preparation process, the present invention utilizes a unique long-spacer arm structure, cleverly addressing the critical issue of deactivation of the active groups of the HEDP retarder due to crosslinking reactions during synthesis. This design enables the HEDP-PEG retarder to successfully build a stable crosslinked network while maintaining its phosphonic acid complexing capacity, ensuring maximum retarder performance. This represents a significant innovation and breakthrough in the field of retarder synthesis.

[0021] Compared to traditional synthesis methods, the preferred aqueous reaction system simplifies the synthesis route and significantly reduces process complexity. Furthermore, the entire synthesis process is environmentally friendly and pollution-free, in line with the development trend of modern green chemistry. The mild reaction conditions and low energy consumption significantly reduce production costs, providing solid technical support for large-scale industrial production and possessing unparalleled advantages in practical applications. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] The present invention provides the following structural formula examples of HEDP-PEG high temperature resistant slow-release retarder: ; Among them, PEG is polyethylene glycol, its molecular weight is 2000-5000, and its structural formula is: , n=45~110; HEDP is an organic phosphine molecule with the structural formula: .

[0024] The present invention also provides the following examples of methods for preparing HEDP-PEG high temperature resistant slow-release retarder: Example 1 Step 1: Pre-reaction of PEG and dibasic anhydride In a reaction flask, dissolve 0.05 mol (150 g) of PEG with a molecular weight of 3000 in 500 mL of DMF, ensuring a homogeneous solution.

[0025] 0.00075 mol (0.009 g) of benzoic acid was added as a catalyst.

[0026] Slowly add 0.1 mol (11.4 g) of glutaric anhydride while stirring. Allow to react at 30-50°C for 4-6 hours, controlling the temperature. During this time, the anhydride groups of the glutaric anhydride react with the hydroxyl groups of the PEG to form a PEG-glutaric anhydride crosslinked intermediate.

[0027] Step 2: Add HEDP for cross-linking reaction After the pre-reaction of PEG-glutaric anhydride was completed, 0.1 mol (20.6 g) of HEDP was added to the reaction system.

[0028] Maintain the reaction temperature at 30-50°C and continue stirring for 8-12 hours to allow the hydroxyl groups in HEDP to undergo esterification with the carboxyl groups of glutaric anhydride to form a stable HEDP-PEG cross-linked network.

[0029] Step 3: Post-processing After the reaction was completed, the reaction solvent was removed using a rotary evaporator.

[0030] The product is washed in anhydrous ethanol and stirred to dissolve the residual organic solvent and small molecular impurities.

[0031] The washed product is placed in a vacuum drying oven for drying to obtain the final retarder product.

[0032] Example 2 High PEG content Step 1: Pre-reaction of PEG and dibasic anhydride In a reaction flask, dissolve 0.1 mol (300 g) of PEG with a molecular weight of 3000 in 500 mL of deionized water, ensuring a homogeneous solution.

[0033] 0.00075 mol (0.009 g) of benzoic acid was added as a catalyst.

[0034] Slowly add 0.1 mol (11.4 g) of glutaric anhydride while stirring, and react at 30-50°C for 4-6 hours while controlling the temperature to generate a PEG-glutaric anhydride cross-linked intermediate.

[0035] Step 2: Add HEDP for cross-linking reaction After the preliminary reaction was completed, 0.1 mol (20.6 g) of HEDP was added.

[0036] Stirring was continued at 30-50°C for 8-12 hours to form a HEDP-PEG cross-linked network.

[0037] Step 3: Post-processing (same as Example 1) Example 3 High PEG Molecular Weight Step 1: Pre-reaction of PEG and dibasic anhydride In a reaction flask, dissolve 0.05 mol (150 g) of PEG with a molecular weight of 2000 in 500 mL of deionized water, ensuring a homogeneous solution.

[0038] 0.00075 mol (0.009 g) of benzoic acid was added as a catalyst.

[0039] Slowly add 0.1 mol (11.4 g) of glutaric anhydride while stirring, and react at 30-50°C for 4-6 hours while controlling the temperature to generate a PEG-glutaric anhydride cross-linked intermediate.

[0040] Step 2: Add HEDP for cross-linking reaction After the preliminary reaction was completed, 0.1 mol (20.6 g) of HEDP was added.

[0041] Stirring was continued at 30-50°C for 8-12 hours to form a HEDP-PEG cross-linked network.

[0042] Step 3: Post-processing (same as Example 1) Example 4 Using different dibasic acid anhydrides Step 1: Pre-reaction of PEG and dibasic anhydride In a reaction flask, dissolve 0.05 mol (150 g) of PEG with a molecular weight of 3000 in 500 mL of DMF, ensuring a homogeneous solution.

[0043] 0.00075 mol (0.009 g) of benzoic acid was added as a catalyst.

[0044] Slowly add 0.1 mol (9.81 g) of maleic anhydride while stirring, and react at 30-50°C for 4-6 hours while controlling the temperature to generate a PEG-maleic anhydride cross-linked intermediate.

[0045] Step 2: Add HEDP for cross-linking reaction After the preliminary reaction was completed, 0.1 mol (20.6 g) of HEDP was added.

[0046] Stirring was continued at 30-50°C for 8-12 hours to form a HEDP-PEG cross-linked network.

[0047] Step 3: Post-processing (same as Example 1) Example 5 Increasing the amount of catalyst molecules added Step 1: Pre-reaction of PEG and dibasic anhydride In a reaction flask, dissolve 0.05 mol (150 g) of PEG with a molecular weight of 3000 in 500 mL of DMF, ensuring a homogeneous solution.

[0048] 0.001 mol (0.122 g) of benzoic acid was added as a catalyst.

[0049] Slowly add 0.1 mol (11.4 g) of glutaric anhydride while stirring, and react at 30-50°C for 4-6 hours while controlling the temperature to generate a PEG-glutaric anhydride cross-linked intermediate.

[0050] Step 2: Add HEDP for cross-linking reaction After the preliminary reaction was completed, 0.1 mol (20.6 g) of HEDP was added.

[0051] Stirring was continued at 30-50°C for 8-12 hours to form a HEDP-PEG cross-linked network.

[0052] Step 3: Post-processing (same as Example 1) Mortar test verification Mortar tests were conducted on the five examples at 55°C. Before mixing, the mortar raw materials were heated to 55°C. After mixing, the mortar was placed in a 55°C oven for insulation. Initial setting time tests were performed every 15 minutes starting from the third hour.

[0053] The mortar formula is 400g of cement C, 800g of sand S, 170g of water W, and 2% of the total weight of the adhesive, using Point-S pure water-reducing admixture (without slump-reducing or retarding properties) produced by KZJ New Materials Group Co., Ltd.

[0054] Wherein, comparative example 1 is a blank control; Comparative Example 2 is a comparison of adding an organic phosphine molecule HEDP as a retarder to the mortar.

[0055] Comparative Example 3 is a comparison of directly adding PEG and organic phosphine molecule HEDP (configured in a molar ratio of 0.05:0.1) into the mortar as a retarder.

[0056] The retarder used in Comparative Example 4 is the retarder of Example 1 except that no dibasic acid anhydride is added. The remaining preparation steps are the same as those of Example 1.

[0057] Table 2. Fluidity and setting time of different retarders at high temperature

[0058] The above results demonstrate that the performance of the retarder prepared by the present invention was evaluated in the aforementioned mortar testing experiments at a high temperature of 55°C. The experimental results clearly demonstrate that, compared with HEDP molecules and other comparative samples, the product of the present invention exhibits superior retarding properties, significantly extending the initial setting time of the mortar and maintaining stable release. This performance advantage is of great significance in practical concrete construction, especially in large-volume concrete construction and high-temperature environments. It can effectively extend construction operation time, ensure concrete construction quality, and avoid various quality issues caused by premature concrete curing, providing reliable technical support for engineering construction.

[0059] The HEDP-PEG retarder of this invention offers moderate cost and ease of large-scale production, making it highly competitive in the market. Its unique thermal stability, temperature sensitivity, and slow-release properties not only meet the urgent needs of summer construction and construction in high-temperature areas, but also offer the potential to expand the application scope of concrete construction technology. For example, it has broad application prospects in projects requiring extremely high retarding properties, such as ultra-long-distance concrete pumping and large-scale water conservancy projects. It is expected to lead a new development trend in the field of concrete admixture technology.

[0060] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 HEDP-PEG high temperature resistant slow-release retarder, characterized in that: The structural formula is: ； Among them, PEG is polyethylene glycol, its molecular weight is 2000-5000, and its structural formula is: ，n=45～110； Among them, HEDP is an organic phosphine molecule with the structural formula: 。 2. A method for preparing a HEDP-PEG high temperature resistant sustained-release retarder, comprising the following steps: S100, in a reaction container, dissolving a certain amount of PEG in a sufficient amount of anhydrous organic solvent, adding a catalyst, and slowly adding a dibasic acid anhydride; stirring while adding, reacting at 30 to 50° C. for 4 to 6 hours to generate a PEG-dibasic acid anhydride cross-linked intermediate; S200, adding a certain amount of HEDP to the reaction system, maintaining the reaction temperature at 30-50°C, and continuously stirring for 8-12 hours to form a stable HEDP-PEG cross-linked network; S300, removing the reaction solvent, and washing the product obtained by removing the solvent in anhydrous ethanol, stirring sufficiently to dissolve the residual anhydrous organic solvent and small molecular impurities, and drying the washed product in a vacuum drying oven to obtain a HEDP-PEG high temperature resistant sustained-release retarder.

3. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: According to the molar ratio, HEDP: dibasic acid anhydride: PEG: catalyst = 1: 1: (0.5~1): (0.005~0.01).

4. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The molecular weight of the PEG is 2000-5000, and its general structural formula is: ，n=45～110； The HEDP is an organic phosphine molecule, and its structural formula is: 。 5. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The PEG-diacid anhydride cross-linked intermediate has a simplified structural formula: PPEG-OC(O)-R-COOH.

6. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The cross-linking agent is a dibasic acid anhydride, and its structural formula is as follows: RC(O)-OC(O)-R'.

7. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The cross-linking agent is one of glutaric anhydride, citric acid, maleic anhydride and succinic anhydride.

8. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The catalyst is a weak acid catalyst, and the usage amount is 0.5% to 1% relative to the molar amount of the dibasic acid anhydride and HEDP.

9. The method for preparing the HEDP-PEG high temperature resistant sustained-release retarder according to claim 2, characterized in that: The anhydrous organic solvent is dimethylformamide or dimethyl sulfoxide.

10. Use of the HEDP-PEG high temperature resistant slow-release retarder according to any one of claims 1 to 9 in concrete construction.

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