A polycarboxylate water-reducing agent prepared from cationic monomers and a preparation method thereof

Abstract

The present invention relates to a polycarboxylate water-reducing agent prepared from a cationic monomer and a preparation method thereof. The raw materials for preparing the polycarboxylate water-reducing agent prepared from the cationic monomer include, by weight: 100 parts of an ester-terminated polyether monomer; 100 parts of a high molecular weight polyether monomer; 2-10 parts of a cationic monomer; 4-10 parts of a functional monomer; 5-12 parts of an unsaturated acid; 0.2-3 parts of a molecular weight regulator; 0.1-2 parts of a reducing agent; 0.5-5 parts of an oxidant; and 150-300 parts of water. The present invention introduces an ester-containing unsaturated polyether monomer into the polycarboxylate water-reducing agent, which has a diverse molecular structure, adjustable hydrophilicity and lipophilicity, and controllable molecular weight. Compared with a traditional water-reducing polycarboxylate water-reducing agent, the polycarboxylate water-reducing agent prepared by the present application has better workability and dispersion retention performance; the cationic monomer is introduced, and the cations contained in the polycarboxylate water-reducing agent reduce the adsorption of soil to an admixture, so that the water-reducing agent molecule has good mud resistance and improves the adaptability of the water-reducing agent.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a polycarboxylate water-reducing agent prepared from a cationic monomer and a preparation method thereof. Background Art

[0002] As the technical requirements for sand and gravel in key projects such as modern concrete and high-speed rail become increasingly higher, and the amount of natural sand and gravel that can meet these requirements is decreasing, in order to meet the rigid demand of the sand and gravel market, machine-made sand has become the first choice in the construction market, and gradually replacing natural sand and gravel materials with machine-made sand has become a necessity for the development of the market situation.

[0003] However, the quality of machine-made sand is difficult to guarantee, and the mud and stone powder content in machine-made sand are relatively high, and the adsorption amount of admixtures is large, which has a great impact on the workability and retention performance of concrete. Summary of the invention

[0004] Based on this, it is necessary to provide a polycarboxylate water-reducing agent prepared from cationic monomers that can reduce sensitivity to clay.

[0005] To achieve the above object, the present invention provides a technical solution:

[0006] A polycarboxylate water-reducing agent prepared from a cationic monomer, wherein the raw materials for preparing the polycarboxylate water-reducing agent prepared from a cationic monomer include, by weight:

[0007]

[0008]

[0009] Preferably, the cationic monomer includes at least one of methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride, dimethyldiallyl chloride and diethyldiallyl ammonium chloride.

[0010] Preferably, the structural formula of the ester-terminated polyether monomer is as follows:

[0011]

[0012] Where R1=(CH2) n , n is an integer from 2 to 8;

[0013] R2 is C1-C 12 A straight-chain or branched saturated alkyl group;

[0014] a is an integer from 0 to 100;

[0015] b is an integer from 0 to 100.

[0016] Preferably, in parts by weight, the raw materials for preparing the ester-terminated polyether monomer include:

[0017] 1 to 15 parts of terminal enol ester;

[0018] 85 to 99 parts of alkylene oxide; and

[0019] 1 to 5 parts of catalyst.

[0020] Preferably, the preparation steps of the ester-terminated polyether monomer include:

[0021] Under the catalysis of a catalyst, the terminal enol ester and the alkylene oxide are subjected to a ring-opening polymerization reaction at 100-120° C. and 0.2-0.5 MPa. After the reaction is completed, the ester-terminated polyether monomer is obtained.

[0022] Preferably, the structural formula of the terminal enol ester is as follows:

[0023]

[0024] Where R1=(CH2) n , n is an integer from 2 to 8;

[0025] R2 is C1-C 12 A straight chain or branched saturated alkyl group.

[0026] The molecular structure of the ester-terminated polyether monomer prepared by the present invention is obtained by block copolymerization of ethylene oxide (EO) and propylene oxide (PO), wherein EO is a hydrophilic group, PO is a lipophilic group, the hydrophilicity and lipophilicity are adjustable, the molecular weight is controllable, and compared with the polyether monomer of the traditional water-reducing polycarboxylic acid water-reducing agent prepared from cationic monomers, the ester-terminated polyether monomer is gradually hydrolyzed in concrete, so that the prepared water-reducing agent has higher slump-retaining performance. The present invention introduces epoxy groups into the macromonomer molecules to form hydrophobic units in the water-reducing agent molecules, thereby overcoming the problems that the water-reducing agent synthesized from traditional straight-chain monomers is easy to bleed and separate, resulting in poor workability of concrete, and the like, thereby greatly improving the workability of the synthesized polycarboxylic acid water-reducing agent prepared from cationic monomers, and further improving the slump-retaining performance.

[0027] Preferably, the catalyst comprises at least one of KOH, NaOH and CH3ONa.

[0028] Preferably, the alkylene oxide includes at least one of ethylene oxide and propylene oxide.

[0029] Preferably, the structural formula of the functional monomer is as follows:

[0030]

[0031] The invention introduces an amide group into the molecular chain of the polycarboxylate water-reducing agent prepared from the cationic monomer, thereby improving the early strength of the polycarboxylate water-reducing agent prepared from the cationic monomer.

[0032] Preferably, the unsaturated acid includes at least one of acrylic acid, methacrylic acid, itaconic acid and maleic acid.

[0033] Preferably, the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate.

[0034] Preferably, the reducing agent includes at least one of L-ascorbic acid, azobisisopropylimidazoline hydrochloride, azobiscyclohexylcarbonitrile, sodium bisulfite and sodium pyrosulfite.

[0035] Preferably, the molecular weight regulator includes at least one of mercaptopropionic acid, sodium hypophosphite, mercaptopropanol and thioglycolic acid.

[0036] The present invention also provides a method for preparing a polycarboxylate water-reducing agent prepared from a cationic monomer as described above, wherein the steps for preparing the polycarboxylate water-reducing agent prepared from a cationic monomer include:

[0037] Stirring and dissolving the ester-terminated polyether monomer, the high molecular weight polyether monomer, the functional monomer, the oxidant and water to obtain a macromonomer mixed solution;

[0038] Mixing the cationic monomer, the unsaturated acid and water to obtain liquid A;

[0039] Mixing the molecular weight regulator, the reducing agent and water to obtain liquid B;

[0040] The A solution and the B solution are simultaneously added dropwise to the macromonomer solution. After the addition is completed, an alkali solution is added to adjust the pH of the solution to 5-7, thereby obtaining the polycarboxylate water-reducing agent prepared from the cationic monomer.

[0041] Beneficial effects of the present invention:

[0042] The present invention introduces ester-terminated polyether monomers into the structure of the polycarboxylate water-reducing agent, which has diverse molecular structures, adjustable hydrophilicity and lipophilicity, and controllable molecular weight. Compared with the traditional water-reducing polycarboxylate water-reducing agent, the polycarboxylate water-reducing agent prepared by the present invention has better workability and dispersion retention performance;

[0043] The present invention introduces cationic monomers into the polycarboxylate water reducer. The cations contained in the polycarboxylate water reducer reduce the adsorption of mud on the admixture, promote the water reducer molecules to have good mud resistance, and improve the adaptability of the water reducer. DETAILED DESCRIPTION

[0044] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0045] In the examples, the test methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0046] 1. Preparation of ester-terminated polyether monomer

[0047] In a SUS high-pressure reactor equipped with a thermometer, a stirrer and a nitrogen inlet pipe, 1-15 parts of terminal ene ester are added as an initiator, and a ring-opening polymerization reaction is carried out with 85-99 parts of alkylene oxide under the action of 1-5 parts of a catalyst at 100-120°C and 0.2-0.5MPa for 2h-4h to obtain the ester-containing unsaturated polyether monomer C.

[0048] In a SUS high-pressure reactor equipped with a thermometer, a stirrer and a nitrogen inlet tube, 10 parts of terminal ene alcohol ester as an initiator, vinyl diethoxyethyl ester, were added, and in the presence of 2 parts of CH3ONa catalyst, a ring-opening polymerization reaction was carried out with 45 parts of ethylene oxide and 45 parts of propylene oxide at 120°C and 0.3 MPa for 4 hours to obtain an ester-terminated polyether monomer C1.

[0049] The raw materials and amounts for preparing ester-terminated polyether monomers C2, C3, and C4 are shown in Table 1, and the other steps are the same as those for preparing ester-terminated polyether monomer C1.

[0050] Table 1 Raw materials and amounts for preparing ester-terminated polyether monomers

[0051]

[0052]

[0053] 2. Preparation of polycarboxylate water reducer prepared from cationic monomers

[0054] S100, adding an ester-terminated polyether monomer, a high molecular weight polyether monomer, an oxidant, a functional monomer and water into a reactor, stirring and dissolving, and obtaining a macromonomer mixed solution;

[0055] S200, stirring and mixing the cationic monomer, unsaturated acid and water to obtain liquid A;

[0056] S300, mixing the molecular weight regulator, the reducing agent and deionized water to obtain liquid B;

[0057] S400, while stirring at room temperature, dropwise add liquid A and liquid B into the macromonomer solution; after the dropwise addition is completed, add alkali to neutralize the pH to 5-7, thereby obtaining a polycarboxylate water-reducing agent prepared from a cationic monomer.

[0058] Example 1

[0059] Preparation of polycarboxylate water reducer prepared from cationic monomers

[0060] S100: adding 100 parts of the ester-terminated polyether monomer C1 prepared above, 100 parts of methyl allyl polyoxyethylene ether with a molecular weight of 5000, 1 part of hydrogen peroxide, 4 parts of functional monomers and 80 parts of deionized water into a reactor, stirring and dissolving, to obtain a macromonomer solution;

[0061] S200: 8 parts of methacryloyloxyethyl trimethyl ammonium chloride, 6 parts of methacrylic acid and 20 parts of deionized water are stirred and mixed to obtain liquid A;

[0062] S300: 3 parts of sodium hypophosphite, 0.2 parts of L-ascorbic acid and 30 parts of deionized water are stirred and mixed to obtain solution B;

[0063] S400: under stirring at room temperature, liquid A and liquid B are simultaneously added dropwise to the macromonomer solution; after the addition is completed, alkali is added to neutralize the pH to 5-7, thereby obtaining a polycarboxylate water-reducing agent prepared from a cationic monomer.

[0064] Specifically, the structural formula of the functional monomer is as follows:

[0065]

[0066] The proportions of Examples 1-4 are shown in Table 2, and the proportions of Comparative Examples 1-4 are shown in Table 3.

[0067] Table 2 Proportion table of Examples 1-4

[0068]

[0069] Table 3 Comparative Examples 1-4 Proportions

[0070]

[0071]

[0072] Concrete performance testing

[0073] The concrete mix ratio is shown in Table 4, where the cement used is Minfu P.O42.5 ordinary Portland cement; the machine-made sand is matched with stone powder, the machine-made sand fineness modulus is 2.8, the mud content is 8% and the powder content is relatively high; the stone powder fineness modulus is 2.7.

[0074] Table 4 Concrete mix ratio (unit: kg / m 3 )

[0075] cement Fly ash Mineral powder Stone powder Machine-made sand Stone water 220 50 80 150 780 900 175

[0076] The polycarboxylate water-reducing agent prepared from the cationic monomer prepared in each embodiment and the comparative example was tested according to the water-reducing agent mother solution, and the test method was based on GB / T 8076-2008 "Concrete Admixtures", GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", and GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete". The test results are shown in Table 5.

[0077] Table 5 Performance test results

[0078]

[0079] As shown in Table 5, the product of the embodiment has good collapse retention performance, good workability, no water seepage, and high 1d compressive strength.

[0080] However, in Comparative Example 1, no ester-containing unsaturated polyether monomer was added, and workability was poor, collapse retention performance decreased significantly, and 1d compressive strength decreased to a certain extent.

[0081] Comparative Example 2 does not add functional monomers, and its 1d compressive strength is lower than that of Comparative Example 1, but its collapse resistance is better than that of Comparative Example 1.

[0082] In Comparative Example 3, no ester-containing unsaturated polyether monomer and functional monomer were added, and the concrete state was obviously poor, with the lowest 1d compressive strength and more water bleeding.

[0083] Comparative Example 4 adds other ester polyether monomers, and the workability is average, the 1d compressive strength is greatly reduced, and there is a certain amount of water bleeding. The 28d compressive strength of the comparative example is about 3-4 MPa less than that of the example.

[0084] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments of the present invention, rather than limiting the present invention; those skilled in the art can make adaptive adjustments within the scope of the present invention.

Claims

1. A polycarboxylate water-reducing agent prepared from a cationic monomer, characterized in that: The raw materials for preparing the polycarboxylate water-reducing agent prepared from the cationic monomer include, by weight: 100 parts of ester-terminated polyether monomer; 100 parts of high molecular weight polyether monomer; 2-10 parts of cationic monomer; 4-10 parts of functional monomer; Unsaturated acid 5-12 parts; Molecular weight regulator 0.2-3 parts; Reducing agent 0.1-2 parts; 0.5-5 parts of oxidizing agent; and 150-300 parts of water; The cationic monomer is at least one of methacryloyloxyethyl trimethyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, dimethyl diallyl ammonium chloride and diethyl diallyl ammonium chloride; The structural formula of the ester-terminated polyether monomer is as follows: ； Where R1=(CH2) n , n is an integer from 2 to 8; R2 is C1-C 12 A straight-chain or branched saturated alkyl group; a is an integer from 0 to 100; b is an integer from 0 to 100; a and b are not 0; The structural formula of the functional monomer is as follows: 。 2. The polycarboxylate water-reducing agent prepared from a cationic monomer according to claim 1, characterized in that: In parts by weight, the raw materials for preparing the ester-terminated polyether monomer include: 1 to 15 parts of terminal enol ester; 85 to 99 parts of alkylene oxide; and 1~5 parts of catalyst; The alkylene oxides are ethylene oxide and propylene oxide.

3. The polycarboxylate water-reducing agent prepared from a cationic monomer according to claim 2, characterized in that: The preparation steps of the ester-terminated polyether monomer include: Under the catalysis of a catalyst, a ring-opening polymerization reaction is carried out on the terminal enol ester and the alkylene oxide at 100-120° C. and 0.2-0.5 MPa. After the reaction is completed, the ester-terminated polyether monomer is obtained.

4. The polycarboxylate water-reducing agent prepared from a cationic monomer according to claim 2, characterized in that: The structural formula of the terminal enol ester is as follows: ； Where R1=(CH2) n , n is an integer from 2 to 8; R2 is C1-C 12 A straight chain or branched saturated alkyl group.

5. The polycarboxylate water-reducing agent prepared from a cationic monomer according to claim 2, characterized in that: The catalyst is at least one of KOH, NaOH and CH3ONa.

6. A method for preparing a polycarboxylate water-reducing agent prepared from a cationic monomer as claimed in any one of claims 1 to 5, characterized in that: The preparation steps of the polycarboxylate water-reducing agent prepared from cationic monomers include: Stirring and dissolving the ester-terminated polyether monomer, the high molecular weight polyether monomer, the functional monomer, the oxidant and water to obtain a macromonomer mixed solution; Mixing the cationic monomer, the unsaturated acid and water to obtain liquid A; Mixing the molecular weight regulator, the reducing agent and water to obtain liquid B; The A solution and the B solution are simultaneously added dropwise to the macromonomer solution. After the addition is completed, an alkali solution is added to adjust the pH of the solution to 5-7, thereby obtaining the polycarboxylate water-reducing agent prepared from the cationic monomer.

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