A phosphorylated protein-based gypsum retarder and preparation method thereof

Abstract

The present invention discloses a phosphorylated protein-based gypsum retarder and a preparation method thereof, and belongs to the technical field of building material retarders. The present invention reacts a phosphate group with a hydroxyl group on a protein product to prepare a phosphorylated protein-based gypsum retarder. Phosphorylation increases the calcium chelating ability of the protein product. In view of the key role of the chelation of calcium ions in the gypsum system by the protein polypeptide in the gypsum system in the retardation of gypsum, the phosphorylated protein-based gypsum retarder prepared by the present invention can more effectively inhibit the hydration of hemihydrate gypsum and the production of dihydrate gypsum by chelating more free calcium ions in the gypsum system, thereby producing a longer-lasting retarding effect on the gypsum, while avoiding the loss of mechanical strength of the gypsum. In addition, the phosphorylated protein-based gypsum retarder prepared by the present invention can effectively improve the fluidity of the gypsum slurry, which is beneficial to the self-leveling construction of the gypsum slurry.

Description

Technical Field

[0001] The invention belongs to the technical field of building material retarders, and in particular relates to a phosphorylated protein-based gypsum retarder and a preparation method thereof. Background Art

[0002] Due to the rapid setting characteristics of gypsum, gypsum retarding technology is essential in the construction process of building gypsum. Usually, gypsum retarding technology is to introduce retarders into gypsum to achieve the effect of extending the setting time of gypsum. Currently, the commonly used gypsum retarders mainly include four categories: small molecule organic acids and their salts, alkaline phosphates, proteins and composite retarders. Among them, small molecule organic acids and their salts and alkaline phosphates have excellent effects in extending the plasticity of gypsum slurry, but the strength of gypsum after hardening is seriously lost. For example, citric acid in organic acids is the gypsum retarder with the best retarding effect. It can meet the retarding requirements of gypsum at a dosage of 0.1% (based on the mass of gypsum), but the strength of gypsum after retarding decreases by more than 50%, which seriously affects the subsequent further application of gypsum materials.

[0003] Compared with small molecule organic acids and alkaline phosphates, protein retarders can not only show good retarding effect in gypsum, but also maintain the basic mechanical properties of gypsum materials. Therefore, protein gypsum retarders have always been a research hotspot in the field of gypsum additives. Many studies have shown that different protein products (leather waste hydrolysate, wheat protein hydrolysate and bone glue, etc.) all show good retarding properties for gypsum, but the retarding effect is not as good as that of small molecule organic acids and alkaline phosphates. According to the research on the retarding mechanism of protein retarders on gypsum, it is shown that protein products mainly chelate calcium ions in the gypsum system through their own structural characteristics (functional groups or conformations), inhibit the hydration of hemihydrate gypsum and the formation of dihydrate gypsum, thereby achieving the retarding effect. The chelation of protein products with calcium ions in the gypsum system has made a huge contribution to the realization of gypsum retarding. Patent CN115947559B provides a method for preparing a keratin polypeptide-based gypsum retarder, which cross-links acidic amino acids with keratin polypeptide products through formaldehyde, giving keratin more active groups to better act on the gypsum system. From the perspective of the setting time and mechanical strength of gypsum, the keratin polypeptide-based gypsum retarder has the advantages of good retarding effect and small strength loss. Compared with the commonly used retarders (citric acid and sodium tripolyphosphate), it has a smaller negative impact on the strength and crystal morphology of gypsum. However, its preparation method is cumbersome and has poor environmental safety. When formaldehyde is used as a cross-linking agent to prepare gypsum retarders, professional equipment is required to control the volatilization of formaldehyde and the reaction process is dangerous. In addition, the prepared retarder product may have formaldehyde residues, and there are potential risks during use.

[0004] Phosphorylation of protein products is one of the methods to increase the calcium chelating ability of protein products. In the field of food research, many studies have used phosphates such as sodium phosphate, sodium hydrogen phosphate and sodium tripolyphosphate for phosphorylation modification of different protein products. The phosphorylated protein product has a significantly increased calcium chelating ability, and the phosphate group has a stronger affinity for calcium ions. However, in the field of gypsum retarder research, phosphorylated protein retarders and their preparation have not yet been proposed. Summary of the invention

[0005] Based on the insufficient retarding effect of existing protein products on building gypsum, the present invention provides a phosphorylated protein-based gypsum retarder and a preparation method thereof. The phosphorylated protein-based gypsum retarder modifies the protein product by phosphate to increase its chelating ability for calcium ions, thereby effectively inhibiting the hydration of hemihydrate gypsum to achieve a long-term retarding effect. At the same time, the present invention also has the advantages of simple and safe process and low cost.

[0006] One of the technical solutions provided by the present invention:

[0007] A method for preparing a phosphorylated protein-based gypsum retarder comprises the following steps: heating and stirring an aqueous solution of a protein product, adding a phosphorylation reagent, adjusting the pH to 8-10, raising the reaction temperature, and performing a phosphorylation reaction; after the reaction is completed, adjusting the pH to neutral to obtain a phosphorylated protein stock solution; dialyzing the phosphorylated protein stock solution to remove the phosphorylation reagent that has not reacted with the protein product; and drying to obtain the phosphorylated protein-based gypsum retarder.

[0008] Preferably, the protein product is collagen hydrolyzate from leather waste, animal hair hydrolyzate, industrial gelatin, bone glue or soy protein. Among them, the main component of collagen hydrolyzate from leather waste is small molecule collagen polypeptide; the main component of industrial gelatin is large molecule polypeptide; the main component of soy protein is plant protein.

[0009] Preferably, the mass of the phosphorylation reagent is 2.5-15% of the mass of the protein product.

[0010] Preferably, the phosphorylation agent is selected from sodium dihydrogen phosphate, sodium hydrogen phosphate, sodium phosphate, sodium tripolyphosphate, sodium pyrophosphate or sodium hexametaphosphate.

[0011] Preferably, the phosphorylation reaction is carried out at a temperature of 40-60°C and for a time of 4-8 h.

[0012] Preferably, the dialysis is performed by dialyzing the phosphorylated protein stock solution against distilled water at 4° C. for 48 h.

[0013] Preferably, the temperature of the heating and stirring is 40°C.

[0014] The second technical solution provided by the present invention is:

[0015] A phosphorylated protein-based gypsum retarder is prepared by the above preparation method.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] The present invention reacts the phosphate group with the hydroxyl group on the protein product to prepare a phosphorylated protein-based gypsum retarder. Phosphorylation increases the calcium chelating ability of the protein product. In view of the key role of the chelation of protein polypeptides with calcium ions in the gypsum system in the retardation of gypsum, the phosphorylated protein-based gypsum retarder prepared by the present invention can more effectively inhibit the hydration of hemihydrate gypsum and the production of dihydrate gypsum by chelating more free calcium ions in the gypsum system, thereby producing a longer retarding effect on the gypsum and avoiding the loss of mechanical strength of the gypsum. In addition, the phosphorylated protein-based gypsum retarder prepared by the present invention can effectively improve the fluidity of the gypsum slurry, which is beneficial to the self-leveling construction of the gypsum slurry; Patent CN115947559B uses formaldehyde to graft acidic amino acids onto protein products, and increases carboxyl groups to bind calcium ions in the gypsum system to enhance the gypsum retarding effect. The phosphate group introduced by the present invention has a higher affinity for calcium ions than the carboxyl group, and has a stronger binding ability to calcium ions, thereby achieving a more significant gypsum retarding effect. In addition, since the phosphate group has a stronger calcium binding ability, it will more effectively prevent the calcium ions in the gypsum system from participating in the hydration reaction. The water molecules in the gypsum system exist in a free state for a long time, which significantly increases the fluidity of the gypsum slurry added with the phosphate gypsum retarder. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 The preparation principle of the phosphorylated protein-based gypsum retarder prepared by the present invention;

[0020] Figure 2 This is a comparison chart of the phosphorylation degree of the phosphorylated protein-based gypsum retarders prepared in Examples 1-6 of the present invention;

[0021] Figure 3 This is a comparison chart of the calcium binding capacity of the phosphorylated protein-based gypsum retarders prepared in Examples 1-6 of the present invention and the gypsum retarders provided in Comparative Examples 1-3. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0024] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0025] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0026] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0027] In the embodiments of the present invention, “parts” refer to “parts by mass” unless otherwise specified.

[0028] It should be noted that, unless otherwise specified, % in Examples and Comparative Examples is based on mass.

[0029] The preparation method of the collagen hydrolyzate of leather waste in the embodiment of the present invention is as follows: a certain mass of leather waste is placed in a reactor, a sodium hydroxide solution with a mass fraction of 8% is added, and the mixture is stirred at 80° C. for 5 hours. After the stirring reaction is completed, the hydrolyzate is neutralized with a hydrochloric acid solution with a mass fraction of 10%, and then the collagen hydrolyzate is collected by filtration, and finally freeze-dried at -70° C. for 48 hours.

[0030] The embodiment of the present invention provides a method for preparing a phosphorylated protein-based gypsum retarder, comprising the following steps:

[0031] (1) Add 50 parts of protein product to a reactor, then add 100 parts of water, and stir at 40°C until completely dissolved and evenly dispersed to obtain a protein solution;

[0032] (2) adding a phosphorylation reagent to the protein solution in step (1), and adjusting the pH to a weak alkaline state with a sodium hydroxide solution having a mass concentration of 30%, then raising the reaction temperature to carry out a phosphorylation reaction. After the reaction is completed, adjusting the pH to a neutral state with a hydrochloric acid solution having a mass fraction of 30%, thereby obtaining a phosphorylated protein stock solution;

[0033] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 h to remove the phosphorylation reagent that has not reacted with the protein product, and then dried to obtain the phosphorylated protein-based gypsum retarder.

[0034] In some preferred embodiments of the present invention, the protein product is one of collagen hydrolysate from leather waste, animal hair hydrolysate, industrial gelatin, bone glue and soy protein.

[0035] In some preferred embodiments of the present invention, the phosphorylation agent is one of sodium dihydrogen phosphate, sodium hydrogen phosphate, sodium phosphate, sodium tripolyphosphate, sodium pyrophosphate and sodium hexametaphosphate. In the embodiments of the present invention and the comparative examples, sodium tripolyphosphate is preferably used for the phosphorylation reaction.

[0036] In some preferred embodiments of the present invention, the mass of the phosphorylation reagent is 2.5-12.5% ​​of the mass of the protein product, the weakly alkaline conditions of the phosphorylation reaction are pH=8-10, the temperature of the phosphorylation reaction is 40-60°C, and the time of the phosphorylation reaction is 4-8 h.

[0037] Figure 1 The invention discloses the preparation principle of the phosphorylated protein-based gypsum retarder prepared by the present invention.

[0038] Example 1 A method for preparing a phosphorylated protein-based gypsum retarder

[0039] (1) Add 50 parts of collagen hydrolyzate from leather waste into a reactor, then add 100 parts of water, and stir at 40°C until it is completely dissolved and evenly dispersed to obtain a protein solution;

[0040] (2) adding 2.5 wt.% sodium tripolyphosphate to the protein solution in step (1), adjusting the pH to 8 with sodium hydroxide solution (mass concentration: 30 wt.%), raising the reaction temperature to 40°C, and carrying out the phosphorylation reaction for 4 hours. After the reaction is completed, adjusting the pH to neutral with hydrochloric acid solution (mass fraction: 30 wt.%) to obtain a phosphorylated protein stock solution;

[0041] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 hours to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein-based gypsum retarder.

[0042] Example 2 Preparation method of phosphorylated protein-based gypsum retarder

[0043] (1) Add 50 parts of collagen hydrolyzate from leather waste into a reactor, then add 100 parts of water, and stir at 40°C until completely dissolved and evenly dispersed to obtain a protein solution;

[0044] (2) Add 7.5wt.% sodium tripolyphosphate to the protein solution in step (1), adjust the pH to 9 with sodium hydroxide solution (mass concentration: 30wt%), increase the reaction temperature to 50°C, and carry out phosphorylation reaction for 6 hours. After the reaction is completed, adjust the pH to neutral with hydrochloric acid solution (mass fraction: 30wt.%) to obtain a phosphorylated protein stock solution;

[0045] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 hours to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein-based gypsum retarder.

[0046] Example 3 Preparation method of phosphorylated protein-based gypsum retarder

[0047] (1) Add 50 parts of collagen hydrolyzate from leather waste into a reactor, then add 100 parts of water, and stir at 40° C. until completely dissolved and evenly dispersed to obtain a protein solution;

[0048] (2) adding 12.5 wt% sodium tripolyphosphate to the protein solution in step (1), adjusting the pH to 10 with a sodium hydroxide solution (mass concentration: 30 wt%), raising the reaction temperature to 60°C, and carrying out the phosphorylation reaction for 8 hours. After the reaction is completed, adjusting the pH to neutral with a hydrochloric acid solution (mass fraction: 30 wt.%) to obtain a phosphorylated protein stock solution;

[0049] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 hours to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein-based gypsum retarder.

[0050] Example 4 Preparation method of phosphorylated protein-based gypsum retarder

[0051] (1) Add 50 parts of industrial gelatin to a reactor, then add 100 parts of water, and stir at 40°C until completely dissolved and evenly dispersed to obtain a protein solution.

[0052] (2) adding 7.5 wt% sodium tripolyphosphate to the protein solution in step (1), adjusting the pH to 9 with sodium hydroxide solution (mass fraction: 30 wt%), raising the reaction temperature to 50°C, and carrying out the phosphorylation reaction for 6 h. After the reaction is completed, adjusting the pH to neutral with hydrochloric acid solution (mass fraction: 30 wt.%) to obtain a phosphorylated protein stock solution;

[0053] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 hours to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein-based gypsum retarder.

[0054] Example 5 A method for preparing a phosphorylated protein-based gypsum retarder

[0055] (1) Add 50 parts of soybean protein to a reactor, then add 100 parts of water, and stir at 40°C until completely dissolved and evenly dispersed to obtain a protein solution;

[0056] (2) adding 7.5 wt.% sodium tripolyphosphate to the protein solution in step (1), adjusting the pH to 9 with sodium hydroxide solution (mass fraction: 30 wt.%), raising the reaction temperature to 50°C, and carrying out the phosphorylation reaction for 6 hours. After the reaction is completed, adjusting the pH to neutral with hydrochloric acid solution (mass fraction: 30 wt.%) to obtain a phosphorylated protein stock solution;

[0057] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 hours to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein gypsum retarder.

[0058] Example 6

[0059] (1) Add 50 parts of collagen hydrolyzate from leather waste into a reactor, then add 100 parts of water, and stir at 40° C. until completely dissolved and evenly dispersed to obtain a protein solution;

[0060] (2) adding 15 wt.% sodium tripolyphosphate to the protein solution in step (1), adjusting the pH to 8 with sodium hydroxide solution (mass concentration: 30 wt.%), raising the reaction temperature to 40°C, and carrying out the phosphorylation reaction for 4 hours. After the reaction is completed, the pH is adjusted to neutral with hydrochloric acid solution (mass fraction: 30 wt.%) to obtain a phosphorylated protein stock solution;

[0061] (3) The phosphorylated protein stock solution obtained in step (2) is dialyzed against distilled water at 4° C. for 48 h to remove phosphate that has not reacted with the protein product, and then spray-dried to obtain a phosphorylated protein-based gypsum retarder.

[0062] The phosphorus content in the phosphorylated protein-based gypsum retarder prepared in Examples 1-6 was determined by phosphomolybdic acid colorimetry and the phosphorylation degree was calculated.

[0063] Phosphorylation degree (mg / g) = phosphorus content in gypsum retarder / mass of gypsum retarder

[0064] The results of the test are as follows Figure 2 As shown in the comparison diagram of the phosphorylation degree of the phosphorylated protein-based gypsum retarder prepared in Examples 1-6, it can be seen from Examples 1-3 that as the phosphorylation reagent increases from 2.5wt% (based on the mass of the protein product) to 7.5% and 12.5%, the phosphorylation degree of the phosphorylated protein-based gypsum retarder gradually increases, indicating that the phosphate groups on the protein retarder molecular chain increase after phosphorylation modification; combined with the analysis of Examples 2, 4 and 5, different protein products have different phosphorylation degrees after the same phosphorylation modification, which is caused by different hydroxyl / amino content or solubility differences of different protein products. It can be seen from Example 6 that when the phosphorylation reagent is excessive (based on 15% of the mass of the protein product), the phosphorylation degree of the phosphorylated protein-based gypsum retarder decreases, which is due to the electrostatic repulsion and steric hindrance effect between the excess phosphate groups in the reaction system and the protein product, resulting in a reduced probability of reaction collision.

[0065] Comparative Example 1

[0066] Collagen hydrolyzate from leather waste is used as gypsum retarder.

[0067] Comparative Example 2

[0068] Industrial gelatin is used as a gypsum retarder.

[0069] Comparative Example 3

[0070] Soy protein as a gypsum retarder.

[0071] Comparative Example 4

[0072] Sodium tripolyphosphate (phosphate gypsum retarder) is used as gypsum retarder.

[0073] Comparative Example 5

[0074] Citric acid (small molecule organic acid gypsum retarder) is used as gypsum retarder.

[0075] The EDTA titration method was used to determine the binding capacity of the gypsum retarders of Examples 1-6 and Comparative Examples 1-3 for calcium ions in the gypsum system. The results are shown in Figure 3Comparison of calcium binding capacity of phosphorylated protein-based gypsum retarders prepared in Examples 1-6 and gypsum retarders provided in Comparative Examples 1-3. Protein products have good affinity for calcium ions and show good binding capacity. Figure 2 and Figure 3 From the results, it can be seen that with the increase of the degree of phosphorylation, the binding ability of the phosphorylated protein-based gypsum retarder (Example 1, Example 2 and Example 3) to free calcium ions in the gypsum system gradually increases, which is significantly higher than that of the unmodified protein product (Comparative Example 1, Comparative Example 2 and Comparative Example 3). This is because the introduction of phosphate groups increases the binding sites for calcium ions.

[0076] According to GB / T17669.4-1994 "Determination of physical properties of building gypsum paste" and GB / T 17669.3-1994 "Determination of physical properties of building gypsum paste", the setting time and mechanical strength of gypsum after adding retarder were measured. The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As shown in Table 1, a phosphorylated protein-based gypsum retarder provided by the present invention can not only meet the long-term plasticity of gypsum slurry, but also can maintain a high mechanical strength after hardening to meet the subsequent application of gypsum-based materials. In combination with the experimental example 3 in Table 1 and the measured data of Example 6, Example 3 shows a more outstanding retarding effect, which is better than the retarding effect of Example 6. This is because the excessive phosphorylation agent reduces the phosphorylation modification effect due to electrostatic repulsion and steric hindrance effects, resulting in a decrease in the binding ability to calcium ions in the gypsum system. Compared with Comparative Examples 1, 2 and 3, the phosphorylated protein-based gypsum retarder prepared by the present invention significantly improves the retarding performance of gypsum, because the phosphorylation modification increases the calcium binding ability of the protein product, more effectively binds to the free calcium ions in the gypsum system, thereby inhibiting the hydration reaction of gypsum to achieve the purpose of efficient retarding. Compared with Comparative Examples 4 and 5, the phosphorylated protein-based gypsum retarder prepared by the present invention can greatly reduce the strength loss caused by the introduction of the retarder while ensuring the efficient retarding time.

[0080] The present invention adds phosphate groups to the protein product molecular chain through phosphorylation modification, thereby improving the binding ability to free calcium ions in the gypsum system, thereby achieving a better gypsum retarding effect. In view of the setting time and mechanical strength of the gypsum, the phosphorylated protein-based gypsum retarder provided by the present invention not only has good retarding performance, but also reduces the loss rate of gypsum strength.

[0081] Comparative Example 6

[0082] A keratin polypeptide-based gypsum retarder was prepared according to Example 3 of patent CN 115947559 B (a method for preparing a keratin polypeptide-based gypsum retarder).

[0083] The fluidity properties of the phosphorylated protein-based gypsum retarders prepared in Examples 1, 2, 3 and 4 of the present invention and the keratin polypeptide-based gypsum retarder prepared in Comparative Example 6 were measured by the JC / T 1023-2021 method. The measurement results are shown in Table 2.

[0084] Table 2

[0085]

[0086] As shown in Table 2, the phosphorylated protein gypsum retarder prepared by the present invention can increase the fluidity of the gypsum slurry, which is beneficial to the self-leveling construction of the gypsum slurry. As the amount of phosphorylated protein gypsum retarder or the degree of phosphorylation increases, the fluidity of the gypsum slurry is improved more significantly.

[0087] Compared with the keratin polypeptide-based gypsum retarder of patent CN 115947559B (Comparative Example 6), the phosphorylated protein gypsum retarder prepared by the present invention can provide better fluidity during the gypsum construction process, which is beneficial to improving the processability of the gypsum slurry. This is because the phosphate group is more effective than the carboxyl group in binding the calcium ions in the gypsum system to inhibit the hydration reaction. Therefore, more water molecules exist in the gypsum system in a free form, so that the gypsum slurry maintains better fluidity.

[0088] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A phosphorylated protein-based gypsum retarder, characterized in that: The preparation method of the phosphorylated protein-based gypsum retarder comprises the following steps: heating and stirring an aqueous solution of a protein product, adding a phosphorylation reagent; adjusting the pH to 8-10, raising the reaction temperature, and performing a phosphorylation reaction; after the reaction is completed, adjusting the pH to neutral to obtain a phosphorylated protein stock solution; dialyzing the phosphorylated protein stock solution to remove the phosphorylation reagent that has not reacted with the protein product, and drying to obtain the phosphorylated protein-based gypsum retarder; The phosphorylation reagent is sodium tripolyphosphate; the mass of the phosphorylation reagent is 2.5-15% of the mass of the protein product.

2. The phosphorylated protein-based gypsum retarder according to claim 1, characterized in that: The protein product is collagen hydrolyzate of leather waste, animal hair hydrolyzate, industrial gelatin, bone glue or soy protein.

3. The phosphorylated protein-based gypsum retarder according to claim 1, characterized in that The phosphorylation reaction is carried out at a temperature of 40-60° C. and for a time of 4-8 h.

4. The phosphorylated protein-based gypsum retarder according to claim 1, characterized in that: The dialysis is performed by dialyzing the phosphorylated protein stock solution against distilled water at 4° C. for 48 h.

5. The phosphorylated protein-based gypsum retarder according to claim 1, characterized in that: The heating and stirring temperature is 40°C.

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