Air entraining type viscosity reducing polycarboxylic acid water reducing agent and preparation method thereof

Abstract

The application discloses an air-entraining type viscosity-reducing polycarboxylic acid water reducing agent and a preparation method thereof. The polycarboxylic acid water reducing agent is prepared from unsaturated polyether macromonomer, unsaturated acid monomer, vinyl polyacetylenic monomer and functional monomer as main raw materials through free radical polymerization under the action of an oxidant, a reducing agent and a chain transfer agent. The introduction of the unsaturated acid monomer can realize good adsorption of the water reducing agent molecules on the particle surface, play an electrostatic repulsion role and further disperse the particles; the vinyl polyacetylenic monomer and the functional monomer are gradiently hydrolyzed in an alkaline cement paste to gradually release carboxyl groups, so that the re-adsorption and dispersion of the water reducing agent molecules on the cement particles are ensured for a long time, thereby effectively reducing the slump loss and improving the workability of concrete. The process is simple, the raw materials are cheap, mass production and manufacturing are facilitated, and the batch concrete selection requirement is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polycarboxylic acid water reducing agent, and particularly relates to an air-entraining viscosity-reducing polycarboxylic acid water reducing agent and a preparation method thereof. BACKGROUND

[0002] In modern construction engineering, as an important building material, the optimization and promotion of the performance of concrete are directly related to the engineering quality, durability and economy. Especially in the field of hydraulic engineering, hydraulic concrete serves in a humid and variable environment for a long time, and the requirement for its durability is more stringent. In order to further improve the performance of polycarboxylic acid water reducing agent and meet the higher durability requirement of concrete in hydraulic engineering, an air-entraining viscosity-reducing polycarboxylic acid water reducing agent emerges as the times require. This new type of water reducing agent not only inherits the original excellent performance of polycarboxylic acid water reducing agent, but also introduces air-entraining mechanism and viscosity-reducing function through specific molecular design.

[0003] The introduction of air-entraining mechanism can effectively improve the durability of concrete, such as freeze-thaw cycle resistance, sea resistance and abrasion resistance. The introduction of appropriate small air bubbles in the concrete can buffer the damage of external stress to the concrete, improve the toughness and durability of the concrete. At the same time, these small air bubbles can also act as a channel for water evaporation, reducing the water pressure in the concrete and preventing the concrete from cracking.

[0004] The realization of viscosity-reducing function helps to reduce the plastic viscosity of concrete and improve the fluidity and pumpability of concrete. This is of great significance to improve the workability of concrete, reduce the construction difficulty and improve the construction efficiency. Especially in the preparation process of high-grade concrete, the application of viscosity-reducing polycarboxylic acid water reducing agent is indispensable.

[0005] Polycarboxylic acid water reducing agent has become a new means to reduce the viscosity of high-strength concrete due to its strong molecular structure designability. The invention with the authorization announcement number CN106883355B discloses a low-air-entraining viscosity-reducing polycarboxylic acid water reducing agent and a preparation method thereof. The polycarboxylic acid water reducing agent is formed by free radical polymerization of an alkyl phosphate triester mixture, iso-pentenyl alcohol polyoxyethylene ether and an unsaturated carboxylic acid under the action of an initiator and a chain transfer agent. The invention introduces an alkyl phosphate triester monomer containing two double bonds into the main chain, so that the obtained polycarboxylic acid water reducing agent molecule has a heterocyclic multi-branched structure, the thickness of the adsorption layer of the polycarboxylic acid water reducing agent is increased, the plastic viscosity of concrete can be significantly reduced, the phosphoric acid triester structure is introduced into the molecular structure of the polycarboxylic acid water reducing agent, the defoaming performance of the obtained polycarboxylic acid water reducing agent can be effectively improved, and the air-entraining property thereof can be reduced. The corresponding product is a viscosity-reducing slump-retaining polycarboxylic acid water reducing agent sold by Zhongjian Commodity Concrete Co., Ltd.

[0006] The patent application with the publication number CN104371081A discloses a preparation method of a fast-dispersing viscosity-reducing polycarboxylic acid cement dispersant, which is based on using an unsaturated macromonomer containing a tertiary amino group as a reducing agent that can participate in polymerization to obtain a hyperbranched polycarboxylic acid cement dispersant, and the obtained polycarboxylic acid cement dispersant has the advantages of high water-reducing rate, fast dispersing speed, and reduced concrete viscosity; and the corresponding existing product is the air-entraining polycarboxylic acid water-reducing agent sold by Jiangsu Subo New Material Co., Ltd.

[0007] However, the products obtained by the above two schemes both have the effect of air-entraining, but the air-stabilizing structure chain strength in the polycarboxylic acid water-reducing agent generally plays a role after being mixed with concrete in practice, so that the water-reducing, slump-retaining, and air-entraining effects are poor, and thus the durability of the concrete is poor. SUMMARY

[0008] The present application aims to provide an air-entraining viscosity-reducing polycarboxylic acid water-reducing agent and a preparation method thereof to solve the problems in the prior art.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical scheme: an air-entraining viscosity-reducing polycarboxylic acid water-reducing agent, the structural general formula of which is shown in Formula 1:

[0010] (1);

[0011] In Formula 1, R1 is selected from H or CH3; R2 is selected from at least one unsaturated carboxylic acid monomer; X is selected from CH2O, C2H4O, or OC4H6O; and a, b, c, d, and n are positive integers from 1 to 50.

[0012] A preparation method of an air-entraining viscosity-reducing polycarboxylic acid water-reducing agent, comprising the following steps:

[0013] Step 1: mixing unsaturated acid monomers, a vinyl polyacetylene monomer dissolved in tetrahydrofuran, a functional monomer, and a chain transfer agent, and then adding water to obtain a mixed solution A, mixing a reducing agent and water to obtain a mixed solution B;

[0014] Step 2: dissolving an unsaturated polyether macromonomer in water at room temperature, completely dissolving, then adding an oxidizing agent, and then respectively adding the mixed solution A and the mixed solution B, stirring and reacting, then keeping warm, and finally cooling to room temperature and diluting with water to a solid content of 50% to obtain the air-entraining viscosity-reducing polycarboxylic acid water-reducing agent.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The air-entraining viscosity-reducing polycarboxylic acid water reducing agent in the application can provide steric hindrance effect after being combined with concrete, guarantee the dispersion of water reducing agent molecules on particles, ensure the re-adsorption-dispersion of water reducing agent molecules on cement particles for a long time, thereby effectively reducing the slump and improving the workability of concrete.

[0017] The preparation method of the air-entraining viscosity-reducing polycarboxylic acid water reducing agent in the application is simple in process, the raw materials are cheap, and the method is suitable for mass production and manufacturing, thereby meeting the batch concrete mixing and selection requirements. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the application will be clearly and completely described below.

[0019] An air-entraining viscosity-reducing polycarboxylic acid water reducing agent, the structural general formula of which is shown in formula 1:

[0020] (1);

[0021] In formula 1, R1 is selected from H or CH3; R2 is selected from at least one of unsaturated carboxylic acid monomers; X is selected from CH2O, C2H4O or OC4H6O; wherein a, b, c, d, n are positive integers from 1 to 50.

[0022] It comprises the following components in parts by weight: 380 parts of unsaturated polyether macromonomer, 5-20 parts of unsaturated acid monomer, 8-15 parts of vinyl polyacetylenic monomer, and 1-10 parts of functional monomer.

[0023] The air-entraining viscosity-reducing polycarboxylic acid water reducing agent is prepared from unsaturated polyether macromonomer, unsaturated acid monomer, vinyl polyacetylenic monomer and functional monomer as main raw materials through free radical polymerization under the action of oxidizing agent, reducing agent and chain transfer agent.

[0024] The unsaturated polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether and isopropyl glycol mono-vinyl polyoxyethylene ether with a molecular weight in the range of 2400-3000;

[0025] The unsaturated acid monomer is at least one of acrylic acid, methacrylic acid, maleic anhydride, sodium methacrylsulfonate and itaconic acid;

[0026] The vinyl polyacetylenic monomer is 4-polyphenylacetylenyl propylene acid diphenyl ester with a molecular weight of 2400, which is prepared from phenylacetylene and 4-ethynyl propylene acid diphenyl ester through active polymerization, the structure general formula of 4-ethynyl propylene acid diphenyl ester is shown in formula 2, and the structure general formula of 4-polyphenylacetylenyl propylene acid diphenyl ester is shown in formula 3.

[0027] (2);

[0028] (3) ;

[0029] The functional monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, ethyl acrylate, and 2-methyl methyl acrylate.

[0030] The oxidizing agent is at least one of ammonium persulfate, hydrogen peroxide, and potassium persulfate, and the amount of the oxidizing agent is 0.2-0.4% of the total mass of the reaction monomers;

[0031] The reducing agent is at least one of L-ascorbic acid, erythorbic acid, ferrous sulfate, sodium thiomethanesulfate, sodium sulfite, and sodium bisulfite, and the amount of the reducing agent is 0.05-0.2% of the total mass of the reaction monomers;

[0032] The chain transfer agent is at least one of mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol, and the amount of the chain transfer agent is 0.2-0.4% of the total mass of the reaction monomers.

[0033] The polycarboxylic acid water-reducing agent reaction equation is shown in Formula 4:

[0034] (4) ;

[0035] When R1 is CH3, X is CH2O or C2H4O; when R1 is H, X is OC4H6O; wherein a, b, c, d, n are positive integers from 1 to 50.

[0036] A method for preparing an air entraining type viscosity reducing polycarboxylic acid water-reducing agent, comprising the following steps:

[0037] Step one: mix unsaturated acid monomers, vinyl polyacetylenic monomers dissolved in tetrahydrofuran, functional monomers, and chain transfer agents, then add water to obtain a mixed solution A, mix a reducing agent and water to obtain a mixed solution B;

[0038] Step two: dissolve the unsaturated polyether macromonomer in water at room temperature, then add an oxidizing agent, then add the mixed solution A and the mixed solution B dropwise, respectively, stir and react, then keep warm, and finally dilute with water to a solid content of 50% after cooling to room temperature to obtain the air entraining type viscosity reducing polycarboxylic acid water-reducing agent; in step two, the dropwise addition time of the mixed solution A is 1-3h, and the dropwise addition time of the mixed solution B is 1.5-3.5h; the reaction temperature is 35°C, and the reaction time is 0.5h-1h.

[0039] The following examples and comparative examples are given in conjunction with the above:

[0040] Example 1

[0041] An air entraining type viscosity reducing polycarboxylic acid water-reducing agent is prepared by the following method:

[0042] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of isopropyl glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were sequentially added, and stirred until fully dissolved to obtain a reactant bottom solution;

[0043] (2) 15 parts of acrylic acid, 10 parts of 4-polyphenylacetylene benzene biphenyl acrylate, 3 parts of hydroxyethyl acrylate, 2 parts of hydroxypropyl acrylate, 1 part of mercaptoethanol and 30 parts of deionized water were mixed to prepare a mixed solution A; 0.6 parts of L-ascorbic acid and 40 parts of deionized water were mixed to prepare a mixed solution B;

[0044] (3) Under stirring, 1.5 parts of hydrogen peroxide was added to the reactant bottom solution, mixed solution B was added first, and mixed solution A was added after 2 minutes, mixed solution A was added for 60 minutes, and mixed solution B was added for 90 minutes; After the addition was completed, it was kept for 60 minutes, and then diluted with water to a solid content of 50%, to obtain an air-entraining viscosity-reducing polycarboxylic acid water reducer.

[0045] Example 2

[0046] An air-entraining viscosity-reducing polycarboxylic acid water reducer was prepared by the following method: (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of isopropyl glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were sequentially added, and stirred until fully dissolved to obtain a reactant bottom solution;

[0047] (2) 12 parts of acrylic acid, 8 parts of 4-polyphenylacetylene benzene biphenyl acrylate, 4 parts of hydroxypropyl acrylate, 1.5 parts of mercaptoacetic acid and 30 parts of deionized water were mixed to prepare a mixed solution A; 0.6 parts of isoascorbic acid and 40 parts of deionized water were mixed to prepare a mixed solution B;

[0048] (3) Under stirring, 1.3 parts of hydrogen peroxide was added to the reactant bottom solution, mixed solution B was added first, and mixed solution A was added after 2 minutes, mixed solution A was added for 60 minutes, and mixed solution B was added for 90 minutes; After the addition was completed, it was kept for 60 minutes, and then diluted with water to a solid content of 50%, to obtain an air-entraining viscosity-reducing polycarboxylic acid water reducer.

[0049] Example 3

[0050] An air-entraining viscosity-reducing polycarboxylic acid water reducer was prepared by the following method:

[0051] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of isopropyl glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water were sequentially added, and stirred until fully dissolved to obtain a reactant bottom solution;

[0052] (2) 8 parts of acrylic acid, 2 parts of sodium methyl allyl sulfonate, 4 parts of 4-polyphenylacetylene acrylate diphenyl, 2 parts of hydroxypropyl acrylate, 1.2 parts of mercapto propionic acid, 0.2 parts of mercapto ethanol and 60 parts of deionized water are mixed to form a mixed solution A; 0.1 parts of ferrous sulfate, 0.5 parts of isoascorbic acid and 40 parts of deionized water are mixed to form a mixed solution B;

[0053] (3) Under the condition of stirring, 1.5 parts of hydrogen peroxide is added to the reactant bottom solution, mixed solution B is added first, and mixed solution A is added after 2 minutes, mixed solution A is added for 90 minutes, and mixed solution B is added for 120 minutes; after the addition is completed, it is kept for 90 minutes, and then diluted with water to a solid content of 50%, thereby obtaining the air-entraining viscosity-reducing polycarboxylate superplasticizer.

[0054] Example 4

[0055] An air-entraining viscosity-reducing polycarboxylate superplasticizer is prepared by the following method:

[0056] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000 and 360 parts of deionized water are sequentially added, and stirred until fully dissolved, thereby obtaining a reactant bottom solution;

[0057] (2) 8 parts of acrylic acid, 4 parts of maleic anhydride, 4 parts of itaconic acid, 4 parts of 4-polyphenylacetylene acrylate diphenyl, 4 parts of ethyl acrylate, 1 part of mercapto ethanol, 0.5 parts of mercapto propionic acid and 30 parts of deionized water are mixed to form a mixed solution A; 0.4 parts of L-ascorbic acid, 0.2 parts of ferrous sulfate and 40 parts of deionized water are mixed to form a mixed solution B;

[0058] (3) Under the condition of stirring, 1.2 parts of ammonium persulfate is added to the reactant bottom solution, mixed solution B is added first, and mixed solution A is added after 2 minutes, mixed solution A is added for 60 minutes, and mixed solution B is added for 80 minutes; after the addition is completed, it is kept for 60 minutes, and then diluted with water to a solid content of 50%, thereby obtaining the air-entraining viscosity-reducing polycarboxylate superplasticizer.

[0059] Comparative Example 1

[0060] An air-entraining viscosity-reducing polycarboxylate superplasticizer is prepared based on Example 2, without adding ene-yne monomers and functional monomers during the preparation process, and the remaining conditions are unchanged. The preparation method is as follows:

[0061] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000 and 360 parts of deionized water are sequentially added, and stirred until fully dissolved, thereby obtaining a reactant bottom solution;

[0062] (2) 24 parts of acrylic acid, 1.5 parts of mercaptoacetic acid and 30 parts of deionized water are mixed to form a mixed solution A; 0.6 parts of erythorbic acid and 40 parts of deionized water are mixed to form a mixed solution B;

[0063] (3) Under the condition of stirring, 1.3 parts of hydrogen peroxide is added to the reactant bottom solution, and the mixed solution B is first added dropwise, and then the mixed solution A is added dropwise after 2 minutes. The mixed solution A is added dropwise for 60 minutes, and the mixed solution B is added dropwise for 90 minutes. After the addition is completed, it is kept for 60 minutes, and then diluted with water to a solid content of 50%, thereby obtaining the air-entraining viscosity-reducing polycarboxylic acid water reducer.

[0064] Comparative Example 2

[0065] An air-entraining viscosity-reducing polycarboxylic acid water reducer is prepared based on Example 2, without adding a functional monomer in the preparation process, and the remaining conditions are maintained. The preparation method is as follows:

[0066] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of isopropyl glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water are sequentially added, and stirred until fully dissolved, thereby obtaining a reactant bottom solution;

[0067] (2) 20 parts of acrylic acid, 4 parts of hydroxypropyl acrylate, 1.5 parts of mercaptoacetic acid and 30 parts of deionized water are mixed to form a mixed solution A; 0.6 parts of erythorbic acid and 40 parts of deionized water are mixed to form a mixed solution B;

[0068] (3) Under the condition of stirring, 1.3 parts of hydrogen peroxide is added to the reactant bottom solution, and the mixed solution B is first added dropwise, and then the mixed solution A is added dropwise after 2 minutes. The mixed solution A is added dropwise for 60 minutes, and the mixed solution B is added dropwise for 90 minutes. After the addition is completed, it is kept for 60 minutes, and then diluted with water to a solid content of 50%, thereby obtaining the air-entraining viscosity-reducing polycarboxylic acid water reducer.

[0069] Comparative Example 3

[0070] An air-entraining viscosity-reducing polycarboxylic acid water reducer is prepared based on Example 2, without adding an ene-yne monomer in the preparation process, and the remaining conditions are maintained. The preparation method is as follows:

[0071] (1) In a glass reactor equipped with a thermometer and a stirrer, 380 parts of isopropyl glycol monovinyl polyoxyethylene ether with a molecular weight of 2400 and 360 parts of deionized water are sequentially added, and stirred until fully dissolved, thereby obtaining a reactant bottom solution;

[0072] (2) 16 parts of acrylic acid, 8 parts of 4-polyphenylacetylene propyl acrylate, 1.5 parts of mercaptoacetic acid and 30 parts of deionized water are mixed to form a mixed solution A; 0.6 parts of erythorbic acid and 40 parts of deionized water are mixed to form a mixed solution B;

[0073] (3) under stirring, 1.3 parts of hydrogen peroxide was added to the reactant bottom solution, mixed solution B was added dropwise first, 2 min later, mixed solution A was added dropwise, mixed solution A was added dropwise for 60 min, mixed solution B was added dropwise for 90 min; after dropwise addition, 60 min of heat preservation was carried out, water was added to dilute to 50% solid content, and an air-entraining type viscosity-reducing polycarboxylic acid water reducing agent was obtained.

[0074] Comparative Example 4

[0075] An air-entraining type polycarboxylic acid water reducing agent sold on the market by Jiangsu Subote New Material Co., Ltd.

[0076] Comparative Example 5

[0077] A viscosity-reducing and slump-retaining type polycarboxylic acid water reducing agent sold on the market by Zhongjian Commercial Concrete Co., Ltd.

[0078] Test Example

[0079] (1) P·O 42.5 cement of Esheng was used to carry out cement paste comparison with the water reducing agents in Examples 1-4 and Comparative Examples 1-5, the water-binder ratio was 0.29, the time change of cement paste fluidity within 0-3 h was tested, and the test results are shown in Table 1.

[0080] Table 1: Test table of paste fluidity in room temperature environment

[0081]

[0082] As can be seen from the data in Table 1, when 4-polyphenylacetylene phenyl acrylate and hydroxypropyl acrylate are used at the same time in Comparative Example 2 and Comparative Example 2, they have better early release and later slump retention effect, which shows that 4-polyphenylacetylene phenyl acrylate has certain water reducing and slump retention effect. At the same time, it can be seen from the data in the table that the cement paste fluidity of Examples 1-4 is better than that of Comparative Examples 1-5 within 0-2 h, and their release rules are basically the same, which shows that the air-entraining type viscosity-reducing polycarboxylic acid water reducing agent synthesized by using 4-polyphenylacetylene phenyl acrylate in Examples 1-4 has better water reducing rate and early slump retention capacity.

[0083] (2) The air entraining type viscosity reducing polycarboxylate superplasticizer prepared in this example 1-4 and comparative example 1-5 and the comparative sample were applied to C60 concrete with the same admixture formula, and the C60 concrete mix proportion was shown in Table 2. The viscosity and slump flow time of the comparative concrete were tested by the inverted slump cone method. The smaller the time of the concrete flowing out of the inverted slump cone, the smaller the viscosity of the concrete. The cement was Esheng cement P·O 42.5, the machine-made sand fineness modulus was 2.6, the gravel was continuous gradation gravel with a particle size of 5-20 mm, the mineral powder was S95 grade mineral powder, and the polycarboxylate superplasticizer was 2.1wt%. The test method referred to GB / T50080-2016 "Standard Test Methods for Properties of Ordinary Concrete", GB / T50080-2016 "Standard Specification for Concrete Air Content" and GB / T50081-2002 "Standard Test Methods for Mechanical Properties of Ordinary Concrete", and the test results were shown in Table 3 and Table 4.

[0084] Table 2 C60 concrete mix proportion (kg / m 3 )

[0085]

[0086] Table 3 C60 concrete test table at room temperature

[0087] Table 4 C60 concrete slump flow time record table at room temperature

[0088]

[0089] It can be seen from Tables 3 and 4 that the air-entraining type viscosity-reducing polycarboxylic acid water reducing agent synthesized in Examples 1-4 can significantly improve the initial and slump retention performance of concrete, increase the air content of concrete, reduce the slump time and reduce the viscosity of concrete. Among them, Example 2 can more effectively reduce the viscosity of concrete and increase the air content of concrete by using 2400 molecular weight isopropyl glycol monovinyl polyoxyethylene ether. Comparative Example 1 has obvious concrete loss, poor concrete state, large slump loss, and other adverse factors such as large viscosity after loss and poor air content due to the lack of combination of unsaturated ester and vinyl polyacetylene monomer in the molecular structure of the water reducing agent; Comparative Example 2 has slightly better concrete loss, and slightly better air content and viscosity after loss, but the initial slump time of concrete is significantly increased, indicating that the introduction of 4-polyphenylacetylene propylene acid diphenyl ester effectively reduces the initial viscosity of concrete. At the same time, the viscosity-reducing and air-entraining effects of Examples 1-4 are better than those of Comparative Examples 4-5 using commercially available viscosity-reducing water reducing agents, and the slump retention and air stability performance is significantly improved compared to Comparative Examples 3 and Comparative Examples 4-5 using commercially available conventional slump retention type polycarboxylic acid water reducing agents, indicating that the air-entraining type viscosity-reducing polycarboxylic acid water reducing agent synthesized in Examples 1-4 has certain air-entraining and air-stability effects due to its unique molecular structure, thereby playing a good water-reducing, slump-retaining, air-entraining and sustained viscosity-reducing role.

[0090] Based on this, in the present application, by introducing an unsaturated polyether macromonomer with a molecular weight of 2400-3000 as a hydrophobic long side chain, a steric hindrance effect is provided to ensure the dispersion of the water reducing agent molecules on the particles; the introduction of an unsaturated acid monomer can achieve good adsorption of the water reducing agent molecules on the particle surface, exerting electrostatic repulsion to further disperse the particles; the vinyl polyacetylene monomer and the functional monomer are gradually hydrolyzed in the alkaline cement paste, gradually releasing carboxyl groups, ensuring the re-adsorption and dispersion of the water reducing agent molecules on the cement particles for a long time, thereby effectively reducing the slump loss and improving the workability of concrete.

[0091] In the present application, the introduction of the vinyl polyacetylene monomer effectively improves the amphiphilicity of the polycarboxylic acid water reducing agent by introducing a hydrophobic long chain, thereby allowing the polycarboxylic acid water reducing agent to have a certain emulsifying effect, making it have an air-entraining effect, thereby increasing the air content of concrete, and the polycarboxylic acid water reducing agent has a certain viscosity-reducing effect due to the increase in air content.

[0092] In the present application, the functional monomer combined with the unsaturated ester group introduced in the molecular structure can continuously exert the re-adsorption-dispersion-viscosity reduction effect on the surface of the cement hydration product, effectively improving the slump loss and air stability of concrete, thereby continuously exerting the viscosity-reducing effect and achieving the effect of reducing the viscosity of concrete in the later stage.

[0093] In the present application, the 2400 molecular weight isopropyl glycol monovinyl polyoxyethylene ether is used, which has shorter side chain and greater steric hindrance than the commonly used 3000 molecular weight, can reduce the viscosity in the concrete, and makes the concrete more easily pumped.

[0094] The above merely describes the preferred embodiments of the present application, but not used to limit the protection scope of the present application.

Claims

1. An air-entraining type viscosity-reducing polycarboxylate water reducer, characterized by, Comprise the following components by weight: unsaturated polyether macromonomer 380 parts, unsaturated acid monomer 5-20 parts, vinyl polyacetylene monomer 8-15 parts, functional monomer 1-10 parts; under the action of oxidizing agent, reducing agent, chain transfer agent, by free radical polymerization reaction; The unsaturated polyether macromonomer is at least one of isoamylenol polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether and isopropyl glycol mono-vinyl polyoxyethylene ether with a molecular weight in the range of 2400-3000; The unsaturated acid monomer is at least one of acrylic acid, methacrylic acid, maleic anhydride, sodium methacrylate and itaconic acid; The vinyl polyacetylene monomer is 4-polyphenylacetylene-based diphenyl acrylate with a molecular weight of 2400, which is prepared by active polymerization of phenylacetylene and 4-ethynyl acrylate diphenyl acrylate, and the structure of 4-ethynyl acrylate diphenyl acrylate is as follows: ； The functional monomer is at least one of hydroxyethyl acrylate and hydroxypropyl acrylate.

2. The air-entraining polycarboxylate water reducer according to claim 1, characterized in that, The oxidizing agent is at least one of ammonium persulfate, hydrogen peroxide and potassium persulfate, and the amount of the oxidizing agent is 0.2-0.4% of the total mass of the reaction monomers; The reducing agent is at least one of L-ascorbic acid, isoascorbic acid, ferrous sulfate, sodium thiomethanesulfate, sodium sulfite and sodium bisulfite, and the amount of the reducing agent is 0.05-0.2% of the total mass of the reaction monomers; The chain transfer agent is at least one of mercaptoacetic acid, mercaptopropionic acid and mercaptoethanol, and the amount of the chain transfer agent is 0.2-0.4% of the total mass of the reaction monomers.

3. The method for preparing an air-entraining polycarboxylate water reducer according to any one of claims 1-2, characterized in that, Comprise the following steps: Step one: mix the unsaturated acid monomer, the vinyl polyacetylene monomer dissolved in tetrahydrofuran, the functional monomer and the chain transfer agent, then add water to obtain a mixed solution A, mix the reducing agent and water to obtain a mixed solution B; Step two: dissolve the unsaturated polyether macromonomer in water at room temperature, then add the oxidizing agent, then add the mixed solution A and the mixed solution B respectively, stir and react, then keep warm, finally cool to room temperature, then dilute with water to a solid content of 50% to obtain the air-entraining type viscosity-reducing polycarboxylic acid water reducer.

4. The method according to claim 3, wherein the method is characterized by, In step two, the dropwise addition time of the mixed solution A is 1-3h, and the dropwise addition time of the mixed solution B is 1.5-3.5h.

5. The method for preparing an air-entraining type viscosity-reducing polycarboxylate superplasticizer according to claim 4, characterized in that, In step two, the reaction temperature is 35℃, and the reaction time is 0.5h-1h.

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