Efficient alkali-resistant gypsum retarder and preparation method thereof

Abstract

The present application belongs to the technical field of gypsum building materials and retarder, and particularly relates to a high-efficiency alkali-resistant gypsum retarder and a preparation method thereof. The gypsum retarder is formed by mixing acrylic acid, polyoxyethylene ether monomer and hydroxy acrylic acid resin to form a low-molecular-weight retarder component, which helps to improve the plasticity of gypsum mortar. If the environment in the later stage is a strong alkaline environment, the ester bond in hydroxyethyl acrylate / acrylic acid hydroxypropyl ester in the system is hydrolyzed under alkaline conditions, and acid is formed again to provide sustained retarding effect for gypsum. The hydroxy acrylic acid resin, sodium aminotri(methylene) phosphonate and the prepared initiator and chain transfer agent have certain enhancing effect on the retarding, flexural and compressive strength and other mechanical properties of gypsum. The prepared alkali-resistant gypsum retarder completely solves the problems of large loss of gypsum setting time and high dosage of retarder under alkaline conditions, and has great economic and practical value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of setting retarders, and particularly relates to a high-efficiency alkali-resistant gypsum setting retarder and a preparation method thereof. BACKGROUND

[0002] Nowadays, gypsum is widely used in the building material industry, and is widely used as a green building material with excellent performance in plastering gypsum, plastering gypsum, gypsum products and other decorative parts. The common problem of gypsum is that it will lose plasticity within a few minutes after being stirred with water under normal circumstances, and then quickly set, which cannot meet the normal construction needs, so it is necessary to add a setting retarder to gypsum products which can prolong the setting time of gypsum, so that the gypsum can maintain a certain plasticity within a certain time range to meet the actual needs of different gypsum materials for construction.

[0003] There are three main types of gypsum setting retarders: inorganic salts, organic acids and proteins. Studies have shown that inorganic salts and organic acids as setting retarders can prolong the setting time of gypsum, but severely reduce the final strength of the hardened body, which is often criticized and affects use; the market mostly uses protein-based gypsum setting retarders, which have excellent performance in weak acid, neutral and weak alkaline (PH 6-8) conditions, and basically meet the needs of construction, but if the PH value exceeds 10, the protein structure will be dissociated under strong alkaline conditions and will be irreversibly damaged. The setting effect of such setting retarders decreases sharply, and a high amount of mixing is often required to achieve the corresponding setting and operating time, but it has a huge impact on the final strength of the gypsum. Today, the use and construction environment of gypsum has changed a lot, and strong alkaline cementitious materials such as ordinary portland cement, calcium oxide, sodium hydroxide (the PH of the entire system is often greater than 10) are added to gypsum production to control the cracking of gypsum. Alkaline environment can easily promote the setting of gypsum, and conventional gypsum setting retarders often require a high amount of mixing to meet the setting time requirements, which not only increases the cost, but also causes storage and setting instability and other problems. In order to solve this problem, the development of an alkali-resistant gypsum setting retarder will greatly improve the application of gypsum building materials and solve some practical problems. SUMMARY

[0004] In view of the above problems, the purpose of the present application is to provide a high-efficiency alkali-resistant gypsum setting retarder and a preparation method thereof.

[0005] The technical content of the present application is as follows:

[0006] The present application provides a high-efficiency alkali-resistant gypsum setting retarder, the components of the gypsum setting retarder include acrylic acid, polyoxyethylene ether monomer, hydroxy acrylic acid resin, anhydrous citric acid, sodium aminotri (methylene) phosphonate, amino acid, initiator, chain transfer agent and water.

[0007] The acrylic acid accounts for 30-50 parts, the polyoxyethylene ether monomer accounts for 20-30 parts, the hydroxy acrylic acid resin accounts for 20-40 parts, the anhydrous citric acid accounts for 10-15 parts, the sodium aminotri(methylene) phosphonate accounts for 8-12 parts, the amino acid accounts for 5-10 parts, the initiator accounts for 3-8 parts, the chain transfer agent accounts for 3-5 parts and the water accounts for 100-200 parts by weight;

[0008] The polyoxyethylene ether monomer comprises one or more of methyl allyl polyoxyethylene ether and allyl polyoxyethylene ether, and the molecular weight is less than or equal to 2000;

[0009] The hydroxy acrylic acid resin comprises hydroxyethyl acrylate or hydroxypropyl acrylate;

[0010] The amino acid comprises one or more of glycine, tyrosine, asparagine, glutamine, serine, threonine and cysteine;

[0011] The initiator is composed of components including persulfate, tartaric acid and sodium lignosulfonate;

[0012] The initiator is prepared by mixing the persulfate and the tartaric acid in deionized water, stirring uniformly, adding the sodium lignosulfonate, and stirring uniformly at a temperature of 70-80 DEG C.

[0013] In the initiator, the concentration of the persulfate is 35-50%, the concentration of the tartaric acid is 10-20%, and the concentration of the sodium lignosulfonate is 5-10%.

[0014] The chain transfer agent is composed of components including mercaptoethanol, potassium ferricyanide and organic silicon powder;

[0015] The chain transfer agent is prepared by mixing the mercaptoethanol solution and the potassium ferricyanide solution at a volume ratio of (3-5):(1-2), stirring uniformly at a temperature of 50-60 DEG C, adding 8-10 wt% of the organic silicon powder, and performing ultrasonic treatment.

[0016] The mercaptoethanol solution is an aqueous solution with a concentration of 50-60%.

[0017] The potassium ferricyanide solution is an aqueous solution with a concentration of 20-25%.

[0018] The application further provides a preparation method of the high-efficiency alkali-resistant gypsum retarder.

[0019] 1) The acrylic acid, the polyoxyethylene ether monomer, the hydroxy acrylic acid resin and the water are mixed and stirred uniformly, then the initiator is added, and the chain transfer agent is added after stirring and mixing uniformly.

[0020] 2) The amino acid is dissolved in water, and the pH is adjusted to 6-7 to obtain an amino acid aqueous solution.

[0021] 3) adding an amino acid aqueous solution into the solution of step 1), adding anhydrous citric acid, sodium aminotri(methylene) phosphonate, and adjusting the pH to 6-7, and stirring uniformly to obtain the gypsum retarder;

[0022] The pH is adjusted by using sodium hydroxide or calcium hydroxide.

[0023] The beneficial effects of the present application are as follows:

[0024] The gypsum retarder with high efficiency and alkali resistance of the present application is prepared by condensing acrylic acid, polyoxyethylene ether monomer and hydroxy acrylic acid resin through hydrogen bond to form a gypsum retarder component with low molecular weight, which helps to improve the plasticity of gypsum mortar; if the environment in the later stage is alkaline, the ester bond in the hydroxyethyl acrylate / hydroxypropyl acrylate in the system is hydrolyzed under alkaline conditions to form acid again, which provides sustained retarding effect for gypsum; in the preparation method of the gypsum retarder, the initiator is prepared by using persulfate, tartaric acid and sodium lignosulfonate, which is used to promote the hydrogen bond association reaction, strengthen the dispersing force of the reactants, weaken the intermolecular force, improve the plastic shaping of the gypsum retarder, and thus increase the setting time; the chain transfer agent is prepared by using mercaptoethanol, potassium ferricyanide and organic silicon powder, which is used to control the molecular weight of the retarder, and a large molecular weight will increase the side effects of the gypsum retarder, and the side effects of reducing the strength loss of gypsum can be reduced by controlling the molecular weight; the amino acid has hydrophilic properties, which further improves the water locking capacity of gypsum and strengthens the plasticity retention time of gypsum, thereby further improving the plasticity operation time of the gypsum retarder under the condition of keeping the overall setting time unchanged; in addition, sodium aminotri(methylene) phosphonate has a strong ability to complex calcium ions, thereby improving the retarding effect of the retarder under alkaline conditions, prolonging the setting time under alkaline system by more than 100%, and improving the flexural and compressive strength by more than 10%, so that the gypsum retarder prepared by the present application has the effects of high efficiency retarding and alkali resistance. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The setting time results of different gypsum retarders with the same dosage added to different gypsums;

[0026] Figure 2 The absolute dry flexural and compressive strength results of different gypsum retarders with the same dosage added to different gypsums;

[0027] Figure 3 The setting time results of different gypsum retarders with the same dosage added to gypsums under different pH systems;

[0028] Figure 4The anti-bending and anti-compressive results of different gypsum retarders added in different PH value systems with the same amount are shown in the figure. DETAILED DESCRIPTION

[0029] The application will be further described in details by specific examples and the accompanying drawings. It should be understood that these examples are only used to illustrate the application and not used to limit the protection scope of the application. After reading the application, the modification of various equivalent forms of the application by the person skilled in the art falls within the claims of the application.

[0030] Unless otherwise specified, all raw materials and reagents of the application are conventional market raw materials and reagents.

[0031] Example 1

[0032] Preparation of a high-efficiency alkali-resistant gypsum retarder

[0033] 1) 40 parts of acrylic acid, 25 parts of allyl polyoxyethylene ether (molecular weight ≤2000), 30 parts of hydroxyethyl acrylate and 200 parts of water are mixed, stirred uniformly, then 5 parts of initiator is added, stirred and mixed uniformly, and then 4 parts of chain transfer agent is added;

[0034] The preparation of the initiator is as follows: mix persulfate and tartaric acid, add deionized water, stir uniformly, then add sodium lignosulfonate, heat to 75℃, and stir uniformly to obtain the initiator. The concentration of persulfate is 40%, the concentration of tartaric acid is 15%, and the concentration of sodium lignosulfonate is 8%;

[0035] The preparation of the chain transfer agent is as follows: mix 55% mercaptoethanol solution and 20% potassium ferricyanide solution in a volume ratio of 3:2, heat to 55℃, stir uniformly, add 8wt% silicone powder, and perform ultrasonic treatment to obtain the chain transfer agent;

[0036] 2) Dissolve 2 parts of glycine, 3 parts of asparagine and 3 parts of cysteine in water, and adjust the pH to 6.5 to obtain an amino acid aqueous solution;

[0037] 3) Add the amino acid aqueous solution to the solution of step 1), add 12 parts of anhydrous citric acid and 10 parts of aminotri-methylene phosphonic acid sodium, adjust the pH to 6.5, and stir uniformly to obtain the gypsum retarder;

[0038] The pH is adjusted by using sodium hydroxide.

[0039] Example 2

[0040] Preparation of a high-efficiency alkali-resistant gypsum retarder

[0041] 1) 30 parts of acrylic acid, 20 parts of methallyl polyoxyethylene ether (molecular weight ≤2000), 20 parts of hydroxypropyl acrylate and 100 parts of water are mixed, after stirring uniformly, 3 parts of initiator is added, after stirring and mixing uniformly, 3 parts of chain transfer agent is added;

[0042] The preparation of the initiator is that: the persulfate and tartaric acid are mixed, added into deionized water, after stirring uniformly, sodium lignosulfonate is added, heated to 70℃, stirred uniformly, and the initiator is obtained, wherein the concentration of persulfate is 35%, the concentration of tartaric acid is 10%, and the concentration of sodium lignosulfonate is 5%;

[0043] The preparation of the chain transfer agent is that: a 50% mercaptoethanol solution and a 25% potassium ferricyanide solution are mixed in a volume ratio of 3:1, heated to 50℃, stirred uniformly, 8wt% silicone powder is added, and ultrasonic treatment is performed, and the chain transfer agent is obtained;

[0044] 2) 2 parts of tyrosine, 2 parts of glutamine and 1 part of serine are dissolved in water, and the pH is adjusted to 7 to obtain an amino acid aqueous solution;

[0045] 3) The amino acid aqueous solution is added to the solution of step 1), 10 parts of anhydrous citric acid and 8 parts of aminotri (methylenephosphonic acid) sodium are added, and the pH is adjusted to 6.5, and the gypsum retarder is obtained after stirring uniformly;

[0046] The pH is adjusted by using calcium hydroxide.

[0047] Example 3

[0048] Preparation of a high-efficiency alkali-resistant gypsum retarder

[0049] 1) 35 parts of acrylic acid, 14 parts of methallyl polyoxyethylene ether (molecular weight ≤2000), 35 parts of hydroxypropyl acrylate and 130 parts of water are mixed, after stirring uniformly, 5 parts of initiator is added, after stirring and mixing uniformly, 5 parts of chain transfer agent is added;

[0050] The preparation of the initiator is that: the persulfate and tartaric acid are mixed, added into deionized water, after stirring uniformly, sodium lignosulfonate is added, heated to 80℃, stirred uniformly, and the initiator is obtained, wherein the concentration of persulfate is 50%, the concentration of tartaric acid is 20%, and the concentration of sodium lignosulfonate is 10%;

[0051] The preparation of the chain transfer agent is that: a 60% mercaptoethanol solution and a 25% potassium ferricyanide solution are mixed in a volume ratio of 4:2, heated to 60℃, stirred uniformly, 10wt% silicone powder is added, and ultrasonic treatment is performed, and the chain transfer agent is obtained;

[0052] 2) Dissolve 2 parts of glycine, 2 parts of threonine and 2 parts of cysteine in water and adjust the pH to 6 to obtain an aqueous amino acid solution;

[0053] 3) Add the aqueous amino acid solution to the solution of step 1), add 14 parts of anhydrous citric acid and 10 parts of sodium aminotrimethylenephosphonate, while adjusting the pH to 6, and stir to obtain a gypsum retarder;

[0054] The pH is adjusted by using sodium hydroxide.

[0055] Example 4

[0056] Preparation of a high-efficiency alkali-resistant gypsum retarder

[0057] 1) Mix 50 parts of acrylic acid, 30 parts of allyl polyoxyethylene ether (molecular weight ≤2000), 40 parts of hydroxyethyl acrylate and 200 parts of water, stir to mix, then add 8 parts of an initiator, stir to mix, then add 5 parts of a chain transfer agent;

[0058] The initiator is prepared by mixing a persulfate and tartaric acid in deionized water, stirring to mix, then adding sodium lignosulfonate, heating to 75°C and stirring to mix, wherein the concentration of the persulfate is 40%, the concentration of the tartaric acid is 15% and the concentration of the sodium lignosulfonate is 8%;

[0059] The chain transfer agent is prepared by mixing a 50% mercaptoethanol solution and a 25% potassium ferricyanide solution in a volume ratio of 5:2, heating to 60°C, stirring to mix, then adding 10 wt% of silicone powder and performing ultrasonic treatment to obtain the chain transfer agent;

[0060] 2) Dissolve 3 parts of tyrosine, 3 parts of asparagine and 4 parts of threonine in water and adjust the pH to 7 to obtain an aqueous amino acid solution;

[0061] 3) Add the aqueous amino acid solution to the solution of step 1), add anhydrous citric acid and sodium aminotrimethylenephosphonate, while adjusting the pH to 7, and stir to obtain a gypsum retarder;

[0062] The pH is adjusted by using calcium hydroxide.

[0063] Comparative Example 1

[0064] A commercially available domestic gypsum retarder: Jiangsu Zhaojia gypsum retarder ZJ-G19.

[0065] Comparative Example 2

[0066] A commercially available imported gypsum retarder: SICIT gypsum retarder Plast Retard PE from Italy.

[0067] The gypsum retarders prepared in the above Examples 1-4 and the comparative examples (commercially available domestic gypsum retarders, commercially available imported gypsum retarders) are used to test the retarding effect on the gypsum of different regions and the alkali resistance of the gypsum retarders.

[0068] 1) The gypsum retarders prepared in the examples are added to different gypsums at the same dosage, and the PH value of the system is tested, and then the setting effect of the gypsum and the mechanical strength are tested, and the results are shown in the following table. (Comparative formula of pure gypsum system: gypsum 998 kg, gypsum retarder 2.0 kg, water 550 kg)

[0069] Table 1: Setting effect and mechanical strength of gypsum

[0070]

[0071] From Table 1, Figures 1-2 It can be seen that compared with the commercially available domestic or imported retarders, the gypsum retarder prepared in the application can effectively prolong the setting time when used in building gypsum, and still maintain excellent bending strength and compressive strength, meeting the construction requirements.

[0072] 2) The gypsum retarders prepared in the examples are added to different gypsums at the same dosage, and the PH value of the system is adjusted to strong alkali (PH>12) with lime, and then the setting effect of the gypsum and the mechanical strength are tested, and the results are shown in the following table. (Comparative formula under strong alkali conditions: gypsum 973 kg, lime 25 kg, gypsum retarder 2.0 kg, water 550 kg)

[0073] Table 2: Setting effect and mechanical strength of gypsum

[0074]

[0075] From Table 2 and Figures 3-4 It can be seen that under strong alkali environment, the gypsum retarder prepared in the application used in building gypsum can still significantly prolong the setting time compared with the commercially available domestic or imported retarders, and the setting time is prolonged under alkaline system, the prolongation rate is more than 100%, the bending and compressive strength is improved by more than 10%, and it has the functions of high-efficiency retarding and alkali resistance.

Claims

1. A highly efficient alkali-resistant gypsum retarder, characterized in that, The components of the gypsum retarder include acrylic acid, polyoxyethylene ether monomer, hydroxy acrylic acid resin, anhydrous citric acid, sodium aminotri(methylene) phosphonate, amino acid, initiator, chain transfer agent and water; In the gypsum retarder, acrylic acid accounts for 30-50 parts, polyoxyethylene ether monomer accounts for 20-30 parts, hydroxy acrylic acid resin accounts for 20-40 parts, anhydrous citric acid accounts for 10-15 parts, sodium aminotri(methylene) phosphonate accounts for 8-12 parts, amino acid accounts for 5-10 parts, initiator accounts for 3-8 parts, chain transfer agent accounts for 3-5 parts and water accounts for 100-200 parts. The hydroxy acrylic acid resin is hydroxyethyl acrylate or hydroxypropyl acrylate. The molecular weight of the polyoxyethylene ether monomer is ≤2000. The initiator is composed of components including persulfate, tartaric acid and sodium lignosulfonate. The chain transfer agent is composed of components including mercaptoethanol, potassium ferricyanide and silicone powder. The preparation is that mercaptoethanol solution and potassium ferricyanide solution are mixed in a volume ratio of (3-5):(1-2), heated to 50-60℃, stirred uniformly, 8-10 wt% of silicone powder is added, and ultrasonic treatment is performed to obtain the chain transfer agent. The mercaptoethanol solution is an aqueous solution with a concentration of 50-60%. The potassium ferricyanide solution is an aqueous solution with a concentration of 20-25%.

2. The efficient alkali tolerant gypsum retarder according to claim 1, characterized in that, The preparation of the initiator is that persulfate and tartaric acid are mixed, deionized water is added, stirred uniformly, then sodium lignosulfonate is added, heated to 70-80℃, and stirred uniformly to obtain the initiator. The concentration of persulfate is 35-50%, the concentration of tartaric acid is 10-20%, and the concentration of sodium lignosulfonate is 5-10%.

3. The efficient alkali tolerant gypsum retarder according to claim 1, characterized in that, The polyoxyethylene ether monomer includes one or more of methyl allyl polyoxyethylene ether and allyl polyoxyethylene ether, and the molecular weight is ≤2000.

4. The efficient alkali tolerant gypsum retarder according to claim 1, characterized in that, The amino acid includes one or more of glycine, tyrosine, asparagine, glutamine, serine, threonine and cysteine.

5. A method for preparing the high-efficiency alkali-resistant gypsum retarder according to any one of claims 1-4, characterized in that, The method includes the following steps: 1) acrylic acid, polyoxyethylene ether monomer, hydroxy acrylic acid resin and water are mixed, stirred uniformly, then initiator is added, stirred and mixed uniformly, and then chain transfer agent is added; 2) amino acid is dissolved in water, and the pH is adjusted to 6-7 to obtain an aqueous amino acid solution; 3) the aqueous amino acid solution is added to the solution of step 1), anhydrous citric acid and sodium aminotri(methylene) phosphonate are added, the pH is adjusted to 6-7, and stirring is performed uniformly to obtain the gypsum retarder.

6. The method of preparing a gypsum retarder according to claim 5, characterized in that, The pH is adjusted by using sodium hydroxide or calcium hydroxide.

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