A polycarboxylate water reducer and preparation method thereof

Abstract

The present invention relates to a polycarboxylate water reducer and a preparation method thereof. The raw materials for preparing the polycarboxylate water reducer include, by weight: 200 parts of ester-terminated polyether monomers; 4-10 parts of functional monomers; 2-10 parts of unsaturated sulfonates; 5-12 parts of unsaturated acids; 0.2-3 parts of molecular weight regulators; 0.1-2 parts of reducing agents; 0.5-5 parts of oxidants; and 150-300 parts of water. The present invention introduces an ester-containing unsaturated polyether monomer into the water reducer molecular chain, with diverse molecular structures, adjustable hydrophilicity and lipophilicity, and controllable molecular weight. Compared with traditional water-reducing polycarboxylate water reducers, the polycarboxylate water reducer prepared by the present invention has better workability and dispersion retention performance; unsaturated sulfonate monomers are introduced, and sulfonic acid groups are used to replace part of carboxyl groups, so that the polymer contains appropriate carboxyl groups and sulfonic acid groups, thereby having stronger resistance to sulfate ions, thereby improving the adaptability of the water reducer to cement and reducing the sensitivity to clay.

Description

Technical Field

[0001] The invention relates to the technical field of concrete admixtures, in particular to a polycarboxylate water reducer 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 reducer that can reduce the sensitivity to clay.

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

[0006] A polycarboxylate water reducer, wherein the raw materials for preparing the polycarboxylate water reducer include, by weight:

[0007]

[0008] Preferably, the unsaturated sulfonate includes at least one of sodium methyl allyl sulfonate, sodium styrene sulfonate, sodium 2-acrylamido-2-methylpropane sulfonate and 5-sulfonyl-1-pentene.

[0009] Preferably, the structural formula of the ester-terminated polyether monomer is as follows:

[0010]

[0011] Where R1=(CH2) n , n is an integer from 2 to 8;

[0012] R2 is C1-C 12 A straight-chain or branched saturated alkyl group;

[0013] a is an integer from 0 to 100;

[0014] b is an integer from 0 to 100.

[0015] Preferably, in parts by weight, the raw materials for preparing the ester-terminated polyether monomer include:

[0016] 1 to 15 parts of terminal enol ester;

[0017] 85 to 99 parts of alkylene oxide; and

[0018] 1 to 5 parts of catalyst.

[0019] Preferably, the preparation steps of the ester-terminated polyether monomer include:

[0020] 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.

[0021] Preferably, the structural formula of the terminal enol ester is as follows:

[0022]

[0023] Where R1=(CH2) n , n is an integer from 2 to 8;

[0024] R2 is C1-C 12 A straight chain or branched saturated alkyl group.

[0025] 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, 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 the traditional straight-chain monomers is easy to bleed and separate, resulting in poor workability of the concrete, thereby greatly improving the workability of the synthesized polycarboxylic acid water-reducing agent, and further improving the slump-retaining performance.

[0026] Preferably, the catalyst comprises at least one of KOH, NaOH and CH3ONa.

[0027] Preferably, the alkylene oxide includes at least one of ethylene oxide and propylene oxide.

[0028] Preferably, the structural formula of the functional monomer is as follows:

[0029]

[0030] The present invention introduces an amide group into the molecular chain of the polycarboxylic acid water-reducing agent, thereby improving the early strength of the polycarboxylic acid water-reducing agent.

[0031] Preferably, the unsaturated acid includes at least one of acrylic acid, methacrylic acid, itaconic acid and maleic acid.

[0032] Preferably, the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate.

[0033] Preferably, the reducing agent includes at least one of L-ascorbic acid, azobisisopropylimidazoline hydrochloride, azobiscyclohexylcarbonitrile, sodium bisulfite and sodium pyrosulfite.

[0034] Preferably, the molecular weight regulator includes at least one of mercaptopropionic acid, sodium hypophosphite, mercaptopropanol and thioglycolic acid.

[0035] The present invention also provides a method for preparing the polycarboxylate water-reducing agent as described in any one of the above items, wherein the preparation steps of the polycarboxylate water-reducing agent include:

[0036] Stirring and dissolving the polyether monomer, the functional monomer, the oxidant and water to obtain a macromonomer mixed solution;

[0037] Mixing the unsaturated sulfonate, the unsaturated acid and water to obtain liquid A;

[0038] Mixing the molecular weight regulator, the reducing agent and water to obtain liquid B;

[0039] 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.

[0040] Beneficial effects of the present invention:

[0041] The present invention introduces an ester-containing unsaturated polyether monomer into the water-reducing agent structure, which has diverse molecular structures, adjustable hydrophilicity and lipophilicity, and controllable molecular weight. Compared with the traditional water-reducing polycarboxylic acid water-reducing agent, the polycarboxylic acid water-reducing agent prepared by the present invention has better workability and dispersion retention performance;

[0042] The present invention introduces unsaturated sulfonate monomers into the water reducing agent molecular chain, and adopts sulfonic acid groups to replace part of the carboxyl groups, so that the polymer contains appropriate carboxyl groups and sulfonic acid groups, thereby having stronger resistance to sulfate ions in cement and clay, thereby improving the adaptability of the water reducing agent to cement and reducing the sensitivity to clay. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 1. Preparation of ester-terminated polyether monomer

[0046] 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.

[0047] In a SUS high-pressure reactor equipped with a thermometer, a stirrer and a nitrogen inlet pipe, 10 parts of terminal ene alcohol ester as an initiator, vinyl diethoxyethyl ester, were added, and under the action 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 0.3MPa for 4 hours to obtain ester-terminated polyether monomer C1.

[0048] 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.

[0049] Table 1 Raw materials and amounts for preparing ester-terminated polyether monomers

[0050] Example Initiator Ethylene oxide Propylene oxide catalyst <![CDATA[C1]]> Vinyl diethoxyethyl ester, 10 parts 45 servings 45 servings <![CDATA[CH3ONa, 2 parts]]> <![CDATA[C2]]> Ethyl vinyl ethoxylate, 15 parts 60 servings 25 servings NaOH, 1 part <![CDATA[C3]]> Vinyl diethoxyethyl ester, 7 parts 25 servings 65 servings KOH, 5 parts <![CDATA[C4]]> Ethyl vinyl ethoxylate, 1 part 40 servings 55 servings <![CDATA[CH3ONa, 4 parts]]>

[0051] 2. Preparation of polycarboxylate water reducer

[0052] S100, adding an ester-terminated polyether monomer, an oxidant, a functional monomer and water into a reactor, stirring and dissolving, and obtaining a macromonomer mixed solution;

[0053] S200, stirring and mixing the unsaturated sulfonate, the unsaturated acid and water to obtain liquid A;

[0054] S300, mixing the molecular weight regulator, the reducing agent and water to obtain liquid B;

[0055] S400, under stirring at room temperature, liquid A and liquid B are simultaneously added dropwise to the macromonomer mixed solution; after the addition is completed, alkali is added to neutralize the pH to 5-7, thereby obtaining a polycarboxylate water reducer.

[0056] Example 1

[0057] Preparation of polycarboxylate water reducer

[0058] S100: adding 200 parts of the ester-terminated polyether monomer C1 prepared above, 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;

[0059] S200: 8 parts of sodium methallyl sulfonate, 6 parts of methacrylic acid and 20 parts of deionized water are stirred and mixed to obtain liquid A;

[0060] 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;

[0061] S400: Add liquid A and liquid B to the macromonomer solution at the same time under stirring at room temperature; after the addition is completed, add alkali to neutralize the pH to 5-7 to obtain a polycarboxylate water reducer.

[0062] Specifically, the structural formula of the functional monomer is as follows:

[0063]

[0064] The proportions of Examples 1-4 are shown in Table 2, and the proportions of Comparative Examples 1-4 are shown in Table 3.

[0065] Table 2 Proportion table of Examples 1-4

[0066]

[0067]

[0068] Table 3 Comparative Examples 1-4 Proportions

[0069]

[0070] Concrete performance testing

[0071] 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 10% and the powder content is relatively high; the stone powder fineness modulus is 2.7.

[0072] Table 4 Concrete mix ratio (unit: kg / m 3 )

[0073]

[0074] The polycarboxylate water-reducing agents prepared in the embodiments and comparative examples were tested according to the water-reducing agent mother liquor, and the test method was based on GB / T8076-2008 "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.

[0075] Table 5 Performance test results

[0076]

[0077] As shown in Table 5, the product of the embodiment has good collapse retention performance, good workability, no water seepage, and high 7d compressive strength.

[0078] However, in Comparative Example 1, no ester-containing unsaturated polyether monomer was added, and the workability was poor, the collapse retention performance decreased significantly, and the 7d compressive strength decreased to a certain extent.

[0079] Comparative Example 2 does not add functional monomers, and the collapse retention performance is reduced to a certain extent, but the collapse retention performance is better than that of Comparative Example 1.

[0080] In Comparative Example 3, no ester-containing unsaturated polyether monomer and functional monomer were added, and the concrete state was obviously poor, with more water bleeding, a significant decrease in collapse retention performance, and poor adaptability.

[0081] Comparative Example 4 did not add sodium methyl allyl sulfonate, had average workability, and had a certain amount of water bleeding. The 7d and 28d compressive strengths of the comparative example were smaller than those of the example.

[0082] 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 reducer, characterized in that: In parts by weight, the raw materials for preparing the polycarboxylate water-reducing agent include: 200 parts of ester-terminated polyether monomer; 4-10 parts of functional monomer; 2-10 parts of unsaturated sulfonic acid and / or unsaturated sulfonate; 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 unsaturated sulfonic acid and / or unsaturated sulfonate is at least one of sodium 2-acrylamido-2-methylpropanesulfonate and 5-sulfonic acid-1-pentene; 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 catalyst is at least one of KOH, NaOH and CH3ONa; The alkylene oxides are ethylene oxide and propylene oxide; 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, b are not 0; The structural formula of the functional monomer is as follows: 。 2. The polycarboxylate water-reducing agent according to claim 1, 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.

3. The polycarboxylate water reducer according to claim 1, 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.

4. A method for preparing the polycarboxylate water-reducing agent according to any one of claims 1 to 3, characterized in that: The preparation steps of the polycarboxylate water reducer include: Stirring and dissolving the ester-terminated polyether monomer, the functional monomer, the oxidant and water to obtain a macromonomer mixed solution; Mixing the unsaturated sulfonic acid and / or unsaturated sulfonate, 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.

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