Modified plant hydrolyzed protein water reducing agent, preparation method and application thereof

Abstract

The application belongs to the field of gypsum building material water reducing agent, and discloses a modified plant hydrolyzed protein water reducing agent, a preparation method and application, the water reducing agent comprises a substance with a structure shown in formula I, wherein a=20-25, b=15-20, x=30-40, y=40-45, and z=5-10.The modified plant hydrolyzed protein water reducing agent has the advantages of small mixing amount, high water reducing rate, small loss of gypsum strength, certain retarding effect, strong adaptability to gypsum-based materials, reduced application of other retarding materials, and reduced cost of gypsum-based additives.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of gypsum building material water reducing agent, more specifically, relates to a modified plant hydrolyzed protein water reducing agent and a preparation method and application. BACKGROUND

[0002] Gypsum, as a kind of abundant and widely existing mineral resources, has a long history of application. It mainly exists in the form of dihydrate gypsum (CaSO4·2H2O) and anhydrous gypsum (CaSO4) in nature. Building gypsum is a cementing material mainly composed of β-hemihydrate gypsum, which is obtained by calcining and dehydrating natural dihydrate gypsum or chemical gypsum. In addition, the amount of industrial by-product gypsum is increasing, and the application and development of industrial by-product gypsum have important environmental protection significance and economic benefits.

[0003] Building gypsum has the advantages of low production energy consumption, high economic benefit, fast setting and hardening speed, short construction period as building materials, light material quality, and good heat preservation and insulation performance, and is gradually widely used in the field of building.

[0004] At present, the commercially available water reducing agents mainly include lignin sulfonate, naphthalene sulfonate and polycarboxylate, which are mostly used in cement-based materials such as concrete and mortar, and have good compatibility with cement and excellent performance. The reason is mainly due to the long cement hydration period and slow hydration heat release, which gives the water reducing agent sufficient time to disperse on the cement particles and stimulate the water reducing performance. Compared with cement-based materials, the hydration time of gypsum-based materials is shorter, and the shortening of initial setting and final setting time leads to the failure of lignin sulfonate, naphthalene sulfonate and polycarboxylate water reducing agents to exert their water reducing and dispersing performance, which is covered by the newly generated gypsum hydrate. The original electrostatic repulsion and steric hindrance theory of cement-based materials and water reducing agents has deviation in the adaptability of gypsum-based materials.

[0005] As one of the main additives of gypsum-based mortar, water reducing agent not only needs to ensure the water reducing rate of gypsum mortar material, but also has little influence on the loss of mortar fluidity. In order to meet the compatibility problem of gypsum-based materials to water reducing agent, the requirements for water reducing agent for gypsum are further improved. Protein additive has the advantage of less influence on the strength of gypsum, and has broad application prospect in gypsum materials. Therefore, it is of great significance to develop protein water reducing agent with small dosage, slow setting and good water reducing effect for the application of gypsum materials. SUMMARY

[0006] The modified plant hydrolyzed protein water reducing agent has the advantages of small mixing amount in a gypsum-based material, high water reducing rate, small strength loss of gypsum, certain retarding effect, strong adaptability to the gypsum-based material, reduced application of other retarding materials, and reduced cost of gypsum-based additives.

[0007] To achieve the above object, the first aspect of the present application provides a modified plant hydrolyzed protein water reducing agent, which comprises a substance with the structure shown in formula I:

[0008]

[0009] wherein a=20-25, b=15-20, x=30-40, y=40-45, and z=5-10.

[0010] The second aspect of the present application provides a preparation method of the modified plant hydrolyzed protein water reducing agent, comprising the following steps:

[0011] S1: hydrolyzing plant protein powder to obtain hydrolyzed protein with free amino groups;

[0012] S2: using water, 2-mercaptoethanol and unsaturated carboxylic monomers to break and substitute the disulfide bond in the hydrolyzed protein to obtain plant protein methacrylic acid graft copolymer;

[0013] S3: using water, acrylic monomers and polyoxyethylene ether monomers to perform free radical polymerization reaction with the aqueous solution of the plant protein methacrylic acid graft copolymer to synthesize the modified plant hydrolyzed protein water reducing agent.

[0014] According to the present application, preferably, the preparation method comprises the following steps:

[0015] (1) alkaline hydrolysis: mixing and stirring plant protein powder, water and hydrolysis catalyst uniformly, and performing hydrolysis reaction at a hydrolysis reaction temperature to obtain a first reaction product; adjusting the pH of the first reaction product to 7-8 to obtain hydrolyzed protein (intermediate of protein-polypeptide and polypeptide-amino acid, SPI, at this time, the polypeptide chain contains more active groups and more reaction sites);

[0016] (2) breakage and substitution modification: mixing and stirring water, hydrolyzed protein, 2-mercaptoethanol, initiator and unsaturated carboxylic monomers uniformly to obtain a second reaction product; mixing the second reaction product with an organic solvent, performing precipitation and centrifugal separation to obtain a precipitate, purifying and drying the precipitate to obtain the plant protein methacrylic acid graft copolymer (SPI-MAA);

[0017] (3) Free radical polymerization reaction: the plant protein methacrylic acid graft copolymer, water, acrylic monomer, polyoxyethylene ether monomer, initiator and chain transfer agent are mixed and stirred uniformly to obtain a third reaction product, the solution pH is adjusted to 7-8 to obtain a modified plant hydrolyzed protein water reducing agent solution, and the modified plant hydrolyzed protein water reducing agent is obtained by spray drying.

[0018] In the present application, the natural plant protein powder is first hydrolyzed to form a series of hydrolyzed protein small molecule intermediates with proteins and polypeptides and amino acids, so that more reactive sites are exposed. Then, the disulfide bonds in the hydrolyzed protein chain are broken and modified to generate a plant protein methacrylic acid graft copolymer, which is then polymerized with acrylic monomers, polyoxyethylene ether monomers and the like by aqueous solution free radical polymerization to form a soybean protein graft copolymer with water reducing and setting retarding functions, i.e. the modified plant hydrolyzed protein water reducing agent.

[0019] According to the present application, preferably in step (1),

[0020] The weight parts of each raw material for preparing the first reaction product are as follows: plant protein powder 20-30 parts, water 40-60 parts and hydrolysis catalyst 10-15 parts;

[0021] The plant protein powder is at least one of soybean protein powder, corn protein powder and wheat protein powder;

[0022] The hydrolysis catalyst is at least one of sodium hydroxide and / or potassium hydroxide;

[0023] The temperature of the hydrolysis reaction is 80-85℃, and the time is 2-3h;

[0024] The pH of the first reaction product is adjusted to 7-8 by using an acid; preferably, the acid is at least one of citric acid, hydrochloric acid, sulfuric acid and tartaric acid, and the amount of the acid is 5-10 parts;

[0025] The molecular weight of the hydrolyzed protein is 3000-30000 Da.

[0026] According to the present application, preferably in step (2),

[0027] The weight parts of each raw material for preparing the second reaction product are as follows: water 50-60 parts, hydrolyzed protein 10-20 parts, 2-mercaptoethanol 5-10 parts, initiator 0.5-1 part and unsaturated carboxylic acid monomer 2-3 parts;

[0028] The initiator is at least one of ammonium persulfate, hydrogen peroxide and vitamin C;

[0029] The unsaturated carboxylic acid monomer is at least one of acrylic acid, itaconic acid, citraconic acid and fumaric acid.

[0030] The second reaction product is prepared under nitrogen protection, the reaction temperature is 50-60℃, and the reaction time is 0.5-6h;

[0031] The organic solvent is at least one of acetone, N,N-dimethylformamide and dimethyl sulfoxide, and the amount is 80-100 parts;

[0032] The obtained precipitate is purified by extraction with ethanol in a Soxhlet extractor, and then dried in a vacuum dryer to constant weight to obtain the plant protein methyl acrylic acid graft copolymer.

[0033] According to the present application, preferably, in step (3),

[0034] The weight parts of each raw material for preparing the third reaction product are as follows: the plant protein methyl acrylic acid graft copolymer 5-10 parts, water 60-80 parts, acrylic monomer 3-5 parts, polyoxyethylene ether monomer 50-60 parts, initiator 1-1.5 parts and chain transfer agent 0.5-1 part;

[0035] The acrylic monomer is at least one of acrylic acid, methacrylic acid and ethyl methacrylate;

[0036] The polyoxyethylene ether monomer is at least one of 2-methyl allyl alcohol polyoxyethylene ether, methallyl polyoxyethylene ether and allyl polyoxyethylene ether, and the molecular weight of the polyoxyethylene ether monomer is controlled to be between 1200-2400 Da;

[0037] The initiator is at least one of ammonium persulfate, potassium persulfate and ascorbic acid-hydrogen peroxide;

[0038] The chain transfer agent is at least one of sodium methacryl sulfonate, mercaptopropionic acid and mercaptoacetic acid;

[0039] The reaction temperature for preparing the third reaction product is 60-70℃, and the reaction time is 2-4h;

[0040] The pH of the solution is adjusted to 7-8 by using a base, preferably, the base is at least one of sodium hydroxide and / or potassium hydroxide, and the amount of the base is 10-15 parts.

[0041] According to the present application, preferably, the stirring speed in each step is independently 500-800r / min.

[0042] The third aspect of the present application provides the modified plant hydrolyzed protein water reducing agent prepared by the preparation method.

[0043] The fourth aspect of the present application provides the application of the modified plant hydrolyzed protein water reducing agent in preparing gypsum-based self-leveling mortar.

[0044] According to the present application, preferably, the mixing amount of the modified plant hydrolyzed protein water reducing agent is 0.05-0.2wt% of the amount of gypsum used for preparing the gypsum-based self-leveling mortar.

[0045] The beneficial effects of the technical solution of the present application are as follows:

[0046] (1) The raw material for preparing the hydrolyzed protein of the present application is widely available, mainly from protein-rich grains such as soybeans, wheat, and corn, and is green and environmentally friendly. In addition, the chemical modification method is relatively simple, the reaction conditions are mild, and the energy consumption is low.

[0047] (2) The water reducing agent prepared by the present application has better and more excellent performance in dispersibility and solubility than the unhydrolyzed and unchemically modified protein-based water reducing agent, and solves the problems of low activity, poor solubility, and easy complexation and entanglement between molecules of macromolecular proteins.

[0048] (3) The hydrolyzed protein-based water reducing agent prepared by the present application has high water reducing rate, good retarding property, and small strength loss compared with the water reducing agent products of the prior art. After chemical modification, the double bond groups are introduced into the plant protein peptide chain of the soybean hydrolyzed protein, and the water solubility, solubility, and chemical group activity of the protein chain are greatly improved. In addition, the grafting of polyoxyethylene ether side chains and active groups such as acrylic acid and sodium methacrylate sulfonate on the modified protein chain can promote the adsorption, dispersion, and retarding properties of the water reducing agent on gypsum, so that the water reducing agent has smaller application amount and more obvious effect in the gypsum self-leveling mortar system.

[0049] Other features and advantages of the present application will be described in detail in the subsequent specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0050] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the different views of the drawings, and in which:

[0051] Figure 1 Fig. 3 shows the FT-IR characterization graph of the modified soybean hydrolyzed protein water reducing agent prepared by the preparation method of the modified plant hydrolyzed protein water reducing agent provided in Embodiment 3 of the present application (wherein Transmittance represents light transmittance; Wavenumbers represent wave numbers). DETAILED DESCRIPTION

[0052] Preferred embodiments of the present application will be described in more detail below. Although the following describes preferred embodiments of the present application, it is to be understood that the application can be carried out in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0053] Example 1

[0054] The present embodiment provides a method for preparing a modified plant hydrolyzed protein water-reducing agent, comprising the following steps:

[0055] (1) Alkaline hydrolysis: 30 parts of soybean protein powder, 60 parts of water and 10 parts of sodium hydroxide are mixed and stirred uniformly, and the temperature is raised to 80°C for 3h of incubation reaction to obtain a first reaction product; 10 parts of citric acid is used to adjust the pH of the first reaction product to 7 to obtain soybean hydrolyzed protein (the molecular weight of the hydrolyzed protein is 3000-30000 Da);

[0056] (2) Breaking and substitution modification:

[0057] 50 parts of water is placed in a container and slowly stirred, and the temperature of the container is controlled at 60°C, 10 parts of the hydrolyzed soybean protein prepared in step (1) is slowly added under stirring, and stirred for 60 min under nitrogen. 5 parts of 2-mercaptoethanol is continuously slowly added and reacted for 2h. Subsequently, 0.5 parts of ammonium persulfate and 2 parts of methacrylic acid are added respectively, and incubated for 2h to obtain a second reaction product; the second reaction product is poured into 80 parts of acetone for precipitation and centrifugal separation, and the obtained precipitate is purified by Soxhlet extractor using ethanol to remove unreacted monomers and homopolymers, and the product is dried to constant weight in a vacuum dryer to obtain a soybean protein methacrylic acid graft copolymer (SPI-MAA);

[0058] (3) Free radical polymerization reaction:

[0059] 5 parts of the soybean protein methacrylic acid graft copolymer (SPI-MAA) prepared in step (2) and 60 parts of water are placed in a reaction container and stirred. Subsequently, 3 parts of acrylic monomer, 1 part of initiator ammonium persulfate, 0.5 parts of chain transfer agent sodium methacrylsulfonate and 50 parts of methyl methacrylate polyoxyethylene ether are added in sequence, and incubated for 3h at 60°C to obtain a third reaction product. 10 parts of 30% sodium hydroxide solution is added to adjust the pH of the mixture to 7-8 to obtain a modified soybean hydrolyzed protein water-reducing agent solution with a solid content of 40%, which is spray dried to obtain a modified soybean hydrolyzed protein water-reducing agent powder, and the structure is as shown in formula I, wherein a=20; b=15; x=30; y=40; z=5.

[0060] Example 2

[0061] The embodiment provides a preparation method of a modified plant hydrolyzed protein water reducing agent, and the embodiment is different from the embodiment 1 only in that:

[0062] Each raw material for preparing the first reaction product is 30 parts of soybean protein powder, 55 parts of water and 15 parts of sodium hydroxide;

[0063] Each raw material for preparing the second reaction product is 60 parts of water, 15 parts of hydrolyzed soybean protein, 8 parts of 2-mercaptoethanol, 0.5 parts of ammonium persulfate and 2 parts of methacrylic acid;

[0064] Each raw material for preparing the third reaction product is 10 parts of soybean protein methacrylic acid graft copolymer (SPI-MAA), 60 parts of water, 3 parts of acrylic monomer, 1 part of initiator ammonium persulfate, 0.8 parts of chain transfer agent sodium methacryl sulfonate and 50 parts of methyl alkenyl polyoxyethylene ether;

[0065] The modified soybean hydrolyzed protein water reducing agent powder has a structure as shown in the formula I, wherein a=25; b=20; x=30; y=40; and z=10.

[0066] Embodiment 3

[0067] The embodiment provides a preparation method of a modified plant hydrolyzed protein water reducing agent, and the embodiment is different from the embodiment 1 only in that:

[0068] Each raw material for preparing the first reaction product is 30 parts of soybean protein powder, 55 parts of water and 15 parts of sodium hydroxide;

[0069] (2) Breakage and substitution modification:

[0070] 60 parts of water are placed in a container and slowly stirred, the temperature of the container is controlled at 50 DEG C, 20 parts of the hydrolyzed soybean protein prepared in the step (1) is slowly added in a stirring state, and stirring is conducted under nitrogen for 60 min. 10 parts of 2-mercaptoethanol is continuously slowly added and reacted for 2 h. Then, 0.8 parts of ammonium persulfate and 2 parts of methacrylic acid are added respectively, and heat preservation reaction is conducted for 2 h, so as to obtain the second reaction product; the second reaction product is poured into 80 parts of acetone for precipitation, and centrifugal separation is conducted, the obtained precipitate is extracted and purified in a Soxhlet extractor by using ethanol, so as to remove unreacted monomers and homopolymers, and the product is dried in a vacuum dryer until the weight is constant, so as to obtain soybean protein methacrylic acid graft copolymer (SPI-MAA);

[0071] Each raw material for preparing the third reaction product is 10 parts of soybean protein methacrylic acid graft copolymer (SPI-MAA), 60 parts of water, 3 parts of acrylic monomer, 1 part of initiator ammonium persulfate, 0.8 parts of chain transfer agent sodium methacryl sulfonate and 50 parts of methyl alkenyl polyoxyethylene ether;

[0072] Powder of modified soybean hydrolyzed protein water reducing agent, structure as formula I, wherein, a = 25; b = 20; x = 40; y = 45; z = 10.

[0073] Test example

[0074] The test example compares the effects and strength loss properties of examples 1-3 with the commonly used commercial product water reducing agent on gypsum-based self-leveling mortar.

[0075] The commonly used commercial product water reducing agent on gypsum-based self-leveling mortar is lignin sulfonate (commercial 1), naphthalene sulfonate (commercial 2) and polycarboxylate (commercial 3);

[0076] The water-cement ratio of the gypsum self-leveling mortar is 0.5;

[0077] In addition to the water reducing agent, the gypsum self-leveling mortar is composed of 1000 parts of desulfurized gypsum, 0.3 parts of low viscosity hydroxypropyl methyl cellulose ether, 0.05 parts of a retarder, 0.6 parts of a defoaming agent, 0.3 parts of a rheological aid, and is mixed and stirred.

[0078] According to JC / T 1023-2007 and JC / T 1023-2021, the setting time, strength and other performance tests are carried out to obtain table 1.

[0079] As shown by the results in table 1, the water reducing agent prepared by the method of the application has the advantages of small dosage, low strength loss rate and long retardation time when applied to gypsum self-leveling mortar; compared with the commonly used lignin sulfonate, naphthalene sulfonate and polycarboxylate water reducing agents on gypsum self-leveling mortar, the retarder in the examples has the advantages of excellent 30 min fluidity, long setting time and high compressive strength, which shows that the hydrolyzed protein water reducing agent mentioned in the application has strong adaptability to gypsum self-leveling mortar and small side effects on gypsum.

[0080] Table 1

[0081]

[0082] The main raw material of the hydrolyzed protein water reducing agent described in examples 1-3 is widely available, which can be plant protein-rich grains such as soybeans, wheat and corn, and is green, low-carbon and high economic benefit, and is suitable for promotion.

[0083] The above has described various embodiments of the application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. Use of modified plant hydrolyzed protein water reducing agent in preparing gypsum-based self-leveling mortar, characterized in that, The preparation method of the modified plant hydrolyzed protein water reducing agent comprises the following steps: (1) Alkaline hydrolysis: plant protein powder, water and hydrolysis catalyst are uniformly mixed and stirred, and hydrolysis reaction is carried out at a hydrolysis reaction temperature to obtain a first reaction product; the pH of the first reaction product is adjusted to 7-8 to obtain a hydrolyzed protein; The weight parts of each raw material for preparing the first reaction product are as follows: plant protein powder 20-30 parts, water 40-60 parts and hydrolysis catalyst 10-15 parts; The plant protein powder is at least one of soybean protein powder, corn protein powder and wheat protein powder; (2) Breakage and substitution modification: water, hydrolyzed protein, 2-mercaptoethanol, initiator and unsaturated carboxylic acid monomer are uniformly mixed and stirred to obtain a second reaction product; the second reaction product is mixed with an organic solvent to carry out precipitation, centrifugal separation, obtain a precipitate and purify and dry to obtain the plant protein methacrylic acid graft copolymer; The weight parts of each raw material for preparing the second reaction product are as follows: water 50-60 parts, hydrolyzed protein 10-20 parts, 2-mercaptoethanol 5-10 parts, initiator 0.5-1 part and unsaturated carboxylic acid monomer 2-3 parts; The unsaturated carboxylic acid monomer is at least one of acrylic acid, itaconic acid, citraconic acid and fumaric acid; (3) Free radical polymerization reaction: the plant protein methacrylic acid graft copolymer, water, acrylic monomer, polyoxyethylene ether monomer, initiator and chain transfer agent are uniformly mixed and stirred to obtain a third reaction product, the pH of the solution is adjusted to 7-8 to obtain a modified plant hydrolyzed protein water reducing agent solution, and spray drying is carried out to obtain the modified plant hydrolyzed protein water reducing agent; The weight parts of each raw material for preparing the third reaction product are as follows: the plant protein methacrylic acid graft copolymer 5-10 parts, water 60-80 parts, acrylic monomer 3-5 parts, polyoxyethylene ether monomer 50-60 parts, initiator 1-1.5 parts and chain transfer agent 0.5-1 part; The acrylic monomer is at least one of acrylic acid, methacrylic acid and ethyl methacrylate; The polyoxyethylene ether monomer is at least one of 2-methyl allyl alcohol polyoxyethylene ether, methallyl polyoxyethylene ether and allyl polyoxyethylene ether.

2. The use according to claim 1, wherein, In step (1), The hydrolysis catalyst is sodium hydroxide and / or potassium hydroxide; The temperature of the hydrolysis reaction is 80-85℃, and the time is 2-3h; The pH of the first reaction product is adjusted to 7-8 by using an acid; The molecular weight of the hydrolyzed protein is 3000-30000 Da.

3. The use according to claim 2, wherein, The acid is at least one of citric acid, hydrochloric acid, sulfuric acid and tartaric acid, and the amount of the acid is 5-10 parts.

4. The use according to claim 1, wherein, In step (2), The initiator is at least one of ammonium persulfate, hydrogen peroxide and vitamin C; The second reaction product is prepared under the condition of nitrogen protection, the reaction temperature is 50-60℃, and the time is 0.5-6h; The organic solvent is at least one of acetone, N,N-dimethylformamide and dimethyl sulfoxide, and the amount is 80-100 parts; The obtained precipitate is extracted and purified in a Soxhlet extractor with ethanol, dried in a vacuum dryer to constant weight to obtain the plant protein methyl acrylic acid graft copolymer.

5. The use according to claim 1, wherein, In step (3), The initiator is at least one of ammonium persulfate, potassium persulfate and ascorbic acid-hydrogen peroxide; The chain transfer agent is at least one of sodium methacrylsulfonate, mercaptopropionic acid and mercaptoacetic acid; The reaction temperature for preparing the third reaction product is 60-70 DEG C, and the time is 2-4 h; The solution pH is adjusted to 7-8 by using a base.

6. Use according to claim 5, wherein, The base is at least one of sodium hydroxide and / or potassium hydroxide, and the amount of the base is 10-15 parts.

7. The use according to claim 1, wherein, The stirring speed in each step is independently 500-800 r / min.

8. The use according to claim 1, wherein, The dosage of the modified plant hydrolyzed protein water reducing agent is 0.05-0.2 wt% of the amount of the gypsum used for preparing the gypsum-based self-leveling mortar.

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