Polycarboxylic acid water reducing agent, its preparation method and application

Abstract

The application belongs to the field of admixtures, and provides a polycarboxylic acid water reducing agent, a preparation method and application thereof. The preparation method of the polycarboxylic acid water reducing agent comprises: in the presence of water, an initiator and a chain transfer agent, performing a polymerization reaction on a comonomer comprising a polyether macromonomer, an unsaturated carboxylic acid, an unsaturated amide and a functional monomer to form a polycarboxylic acid, wherein the functional monomer is an esterification product of rhamnolipid and an unsaturated alcohol. The polycarboxylic acid water reducing agent of the application has improved workability while maintaining a high water reducing rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of admixtures, and in particular, a polycarboxylic water reducer, a preparation method and application thereof are provided. BACKGROUND

[0002] With the continuous development of modern building technology, the requirements for the performance of concrete in engineering are also increasing. As an important component of high-performance concrete, water reducer has attracted increasing attention in the industry. Polycarboxylic water reducer has the advantages of low dosage, high water-reducing rate, good slump retention performance, good dispersibility, and better workability and durability, and is known as the third generation of concrete water reducer.

[0003] In high-strength concrete, the total amount of cementing material is large, and the water demand will increase. However, in order to improve the compactness and strength, it is necessary to reduce the water-cement ratio. The consequences of increasing the amount of cement and reducing the water-cement ratio are that the viscosity of the concrete increases and the rheological property becomes worse. In the production and application of high-strength concrete, the polycarboxylic water reducer currently used faces the following main problems: (a) the water-reducing rate of the water reducer is insufficient, which makes the high-strength concrete have insufficient fluidity and is difficult to construct; (b) high-strength concrete usually needs to be mixed with more water reducer, and the dispersion of water reducer molecules in concrete requires a certain time, so it needs to be stirred for a longer time, which affects the production efficiency and is easy to cause water bleeding, resulting in poor workability; (c) the viscosity of high-strength concrete is large, and it is difficult to pump. SUMMARY

[0004] In view of the above problems existing in the prior art, the purpose of the present application is to provide a polycarboxylic water reducer, a preparation method and application thereof. The polycarboxylic water reducer of the present application has improved workability while maintaining a high water-reducing rate.

[0005] In a first aspect, the present application provides a preparation method of a polycarboxylic water reducer, which comprises: in the presence of water, an initiator and a chain transfer agent, polymerizing a polyether macromonomer, an unsaturated carboxylic acid, an unsaturated amide and a functional monomer to form a polycarboxylic acid; wherein the functional monomer is an esterification product of rhamnolipid and an unsaturated alcohol.

[0006] In the method of the present application, the functional monomer is used to participate in copolymerization, so that rhamnolipid is introduced into the molecular structure of the polycarboxylic acid, the rhamnolipid has lower surface tension and exhibits better dispersibility in water, the cyclic structure of the rhamnolipid can improve steric hindrance, improve the dispersing performance and stability of the concrete slurry, and reduce the viscosity of the slurry; the amide group is introduced into the side chain of the polycarboxylic acid molecular chain by copolymerization of the unsaturated amide monomer, the unsaturated carboxylic acid and the polyether macromonomer, so that the slump retention performance of the polycarboxylic acid water reducing agent is improved. The functional monomer, the unsaturated amide monomer, the unsaturated carboxylic acid and the polyether macromonomer are used as monomers for copolymerization, so that the prepared polycarboxylic acid water reducing agent maintains high water reducing effect, promotes rapid dispersion of freshly mixed concrete, saves the mixing time of production enterprises, improves production efficiency, and can improve the phenomenon of reverse increase of the fluidity of concrete caused by low temperature.

[0007] In some embodiments of the present application, the mass ratio of the polyether macromonomer, the unsaturated carboxylic acid, the unsaturated amide and the functional monomer is 200:(10-25):(0.2-2):(0.5-2).

[0008] In some embodiments of the present application, the temperature of the polymerization reaction is 5-40℃, and the reaction time is 2-6h.

[0009] In some embodiments of the present application, the unsaturated alcohol is selected from one or more of 2-methyl-3-buten-1-ol, 2-methyl-2-propen-1-ol and 2-methoxy-3-buten-1-ol.

[0010] In some embodiments of the present application, in the preparation of the functional monomer, the molar ratio of the rhamnolipid to the unsaturated alcohol is 1:(1-2).

[0011] In some embodiments of the present application, the functional monomer is prepared by esterification reaction of the rhamnolipid and the unsaturated alcohol under the protection of inert gas in the presence of a catalyst and a polymerization inhibitor.

[0012] Further, the temperature of the esterification reaction is 70-90℃, and the reaction time is 3-8h.

[0013] In some embodiments of the present application, the polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether, methyl allyl alcohol polyoxyethylene ether, ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether.

[0014] In some embodiments of the present application, the unsaturated carboxylic acid is acrylic acid and / or methacrylic acid.

[0015] In some embodiments of the present application, the unsaturated amide is at least one selected from the group consisting of acrylamide, methacrylamide, N-hydroxymethyl acrylamide and 2-acrylamido-2-methylpropane sulfonic acid.

[0016] In some embodiments of the present application, the chain transfer agent is at least one selected from the group consisting of mercaptoethanol, mercaptoacetic acid, mercapto-propanol, mercapto-propanoic acid, trisodium phosphate, sodium formate and sodium acetate.

[0017] In some embodiments of the present application, the mass amount of the chain transfer agent is 0.2% to 2% of the mass of the polyether macro-monomer.

[0018] In some embodiments of the present application, the initiator is a redox initiator.

[0019] In some embodiments of the present application, the mass amount of the initiator is 0.1% to 2% of the mass of the polyether macro-monomer.

[0020] In some embodiments of the present application, the preparation method comprises the following steps:

[0021] (1) dissolving the polyether macro-monomer, functional monomer and oxidizing agent in water to obtain a bottom solution, under stirring and at a temperature of 5 to 40°C, adding A solution to the bottom solution dropwise, after 1 to 10 minutes of dropwise addition of A solution, starting to add B solution, after 1 to 10 minutes of dropwise addition of B solution, starting to add C solution; wherein,

[0022] The A solution is an aqueous solution of the unsaturated carboxylic acid, and the dropwise addition time of A solution is t1;

[0023] The B solution is a mixed aqueous solution of the reducing agent and the chain transfer agent, and the dropwise addition time of B solution is t2;

[0024] The C solution is an aqueous solution of the unsaturated amide, and the dropwise addition time of C solution is t3;

[0025] t1 is 1.0 to 2.5 hours, t2 is 1.5 to 3 hours, and t3 is 1.0 to 2.5 hours;

[0026] (2) after the dropwise addition of the solutions is completed, continuing to react for 0.5 to 2 hours to form a polycarboxylic acid.

[0027] The application can realize the regulation of the sequence of the molecular structure units of the polycarboxylic acid by controlling the dropping sequence and dropping time of the A, B and C solutions, and obtain the copolymer product (polycarboxylic acid) with obvious difference, and promote the dispersion of the polycarboxylic acid on the cement particles; compared with the simultaneous dropping of the three solutions, the water reducing agent prepared by using the foregoing different dropping mode has a smaller difference in the spread of the concrete within 2 minutes of stirring, avoids the phenomenon of too slow flow rate of the concrete, can effectively improve the dispersion speed and has an effective viscosity reduction effect.

[0028] Optionally, the preparation method further comprises: (3) adjusting the pH of the product obtained in step (2) to 6-7 by an alkali.

[0029] In some embodiments of the application, the amount of water is such that the solid content of the prepared polycarboxylic acid water reducing agent is 40%-60%.

[0030] In a second aspect, the application provides a polycarboxylic acid water reducing agent prepared by the preparation method of the first aspect of the application.

[0031] The polycarboxylic acid water reducing agent of the application belongs to a glycolipid modified polycarboxylic acid water reducing agent, and the water reducing agent can realize the rapid dispersion of the slurry, save the stirring time, effectively reduce the viscosity of the concrete and improve the workability when applied to high-strength concrete. In addition, the polycarboxylic acid water reducing agent also has high storage stability, so that the polycarboxylic acid water reducing agent still has a good appearance after long-term storage.

[0032] In a third aspect, the application provides the use of the polycarboxylic acid water reducing agent of the second aspect of the application in building materials.

[0033] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description, or can be learned by practice of the application. DETAILED DESCRIPTION

[0034] Embodiments of the application are described in detail below. The embodiments described below are exemplary only, and are not to be construed as limiting the application.

[0035] The ranges disclosed herein are inclusive of the endpoints and all the intermediate points. The disclosure of a range implies that any and every sub-range within the indicated range is also contemplated. For example, a range of "1 to 10" implies that any and every sub-range between (and including) the minimum value of 1 and the maximum value of 10, e.g., 7 to 8, is also contemplated. The same applies to a range described as being "between" two values. For example, a range of "between 1 and 10" implies that any and every sub-range between (and including) the minimum value of 1 and the maximum value of 10, e.g., 7 to 8, is also contemplated.

[0036] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0037] The first aspect of the present application provides a preparation method of a polycarboxylic acid water reducing agent, the preparation method comprising: polymerizing a comonomer comprising a polyether macromonomer, an unsaturated carboxylic acid, an unsaturated amide and a functional monomer in the presence of water, an initiator and a chain transfer agent to form a polycarboxylic acid.

[0038] In the present application, the polyether macromonomer can be selected from various ether macromonomers having carbon-carbon double bonds. Preferably, the polyether macromonomer is selected from at least one of iso-pentenyl alcohol polyoxyethylene ether (TPEG), methyl allyl alcohol polyoxyethylene ether (HPEG), ethylene glycol monovinyl polyethylene glycol ether (EPEG) and 4-hydroxybutyl vinyl polyoxyethylene ether (VPEG).

[0039] In some embodiments, the average molecular weight (Mw) of the polyether macromonomer is 2000-4000.

[0040] As some specific examples, the polyether macromonomer can be one or more of EPEG-2400, EPEG-3000, TPEG-2400, TPEG-2400, HPEG-2400. The polyether macromonomer of the present application can be prepared by methods well known in the art, or can be obtained commercially, for example, from polyether products selected from Okchem Co., Ltd., Fujian Zhongshan Chemical Co., Ltd., Jiahua Chemical Quanzhou Co., Ltd.

[0041] In the present application, the functional monomer is an esterification product of rhamnolipid and unsaturated alcohol, wherein the rhamnolipid can be one or more of monosaccharide monoester structure, monosaccharide diester structure, disaccharide monoester structure, disaccharide diester structure rhamnolipid.

[0042] As some embodiments, the rhamnolipid has any one of the structures shown in formula 1-1 (monosaccharide monoester), formula 1-2 (monosaccharide diester), formula 1-3 (disaccharide monoester), formula 1-4 (disaccharide diester):

[0043]

[0044] wherein m is any integer from 1 to 10, specifically can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; n is any integer from 1 to 10, specifically can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0045] The source of the rhamnolipid is not particularly required in the present application, and the rhamnolipid can be synthesized by fermentation or chemical method known in the art, or can be directly obtained by commercial purchase, such as but not limited to, rhamnolipid (effective active content of 100%) produced by Wincreate Special Chemical (Shanghai) Co., Ltd., and rhamnolipid (purity ≥ 95%) produced by Shanghai Mayreal Biochemical Technology Co., Ltd.

[0046] In the present application, the unsaturated alcohol can be an unsaturated monohydric alcohol having a double bond. According to some embodiments, the structure of the unsaturated alcohol is shown in formula 2:

[0047]

[0048] wherein L represents a substituted or unsubstituted linear alkylene group having 1-4 carbon atoms, and the substituent is methoxy (-OCH3) or methyl (-CH3). Specific examples of the linear alkylene group having 1-4 carbon atoms include methylene (-CH2-), ethylene (-CH2CH2-), n-propylene (-CH2CH2-) or n-butylene (-CH2CH2CH2CH2-).

[0049] Preferably, the unsaturated alcohol is selected from one or more of 2-methyl-3-buten-1-ol, 2-methyl-2-propen-1-ol and 2-methoxy-3-buten-1-ol.

[0050] In the present application, the rhamnolipid reacts with the hydroxyl group (-OH) provided by the unsaturated alcohol through esterification reaction using the carboxyl group (-COOH) provided by the rhamnolipid, and small molecule water is removed to form the functional monomer. For example, the rhamnolipid shown in formula 1-1 and the unsaturated alcohol shown in formula 2 can produce the functional monomer (esterification product) shown in formula a:

[0051]

[0052] In some embodiments, the molar ratio of the amount of the rhamnolipid to the amount of the unsaturated alcohol can be 1:(1-2), such as 1:1, 1:1.2, 1:1.5, 1:1.7, 1:1.8, 1:2, etc.

[0053] In some embodiments, the temperature of the esterification reaction can be 70-90°C, such as 80°C, 85°C, 90°C, etc., and the reaction time can be 3-8h, such as 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0054] As some preferred embodiments, the functional monomer is prepared by esterification reaction of the rhamnolipid and the unsaturated alcohol in the presence of a catalyst and a polymerization inhibitor, and the esterification reaction is carried out under the protection of an inert gas (such as nitrogen).

[0055] In the present application, the catalyst can be selected from various acid catalysts. Preferably, the catalyst is at least one of benzene sulfonic acid, p-toluene sulfonic acid and ethyl sulfonic acid.

[0056] In the present application, the amount of the catalyst can be selected according to the total amount of the reactants. Preferably, the mass amount of the catalyst is 0.5% to 5%, such as 0.5%, 0.6%, 0.8%, 0.9%, 1.0%, 1.1%, 1.3%, 1.5%, 1.6%, 1.8%, 2%, 2.5%, 3%, 4%, etc. of the total mass of the rhamnolipid and the unsaturated alcohol.

[0057] In the present application, the polymerization inhibitor can reduce the possibility of self-polymerization of the unsaturated alcohol, and the specific type is well known in the art. As some preferred examples, the polymerization inhibitor is at least one of hydroquinone, phenothiazine and diphenylamine.

[0058] In the present application, the amount of the polymerization inhibitor can be selected according to the total amount of the reactants. Preferably, the mass amount of the polymerization inhibitor is 0.3% to 3%, such as 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.7%, 2%, 2.2%, 2.5%, etc. of the total mass of the rhamnolipid and the unsaturated alcohol.

[0059] In the present application, the amount of the functional monomer can be selected according to the amount of the polyether macro-monomer. According to some embodiments, the mass ratio of the polyether macro-monomer to the functional monomer is 200:(0.5-2), such as 200:0.5, 200:0.8, 200:1, 200:1.2, 200:1.5, 200:1.6, 200:2, etc. In this way, the rapid dispersion of the concrete can be promoted while the viscosity reduction effect is further improved.

[0060] In the present application, the unsaturated amide can be selected from various aliphatic amide monomers having carbon-carbon double bond. Preferably, the unsaturated amide is at least one of acrylamide (AM), methacrylamide (MAM), N-hydroxymethyl acrylamide, 2-acrylamido-2-methylpropane sulfonic acid (AMPS).

[0061] In the present application, the amount of the unsaturated amide can be selected according to the amount of the polyether macro-monomer. According to some embodiments, the mass ratio of the polyether macro-monomer to the unsaturated amide is 200:(0.2-2), such as 200:0.2, 200:0.4, 200:0.5, 200:0.6, 200:0.8, 200:1, 200:1.2, 200:1.5, etc. In this way, the slump retention performance of the water reducing agent is improved while the water reducing agent molecular chain maintains a high number of carboxyl groups, improving the adsorption capacity of the water reducing agent on the surface of the cement particles to improve the dispersibility.

[0062] In the present application, the unsaturated carboxylic acid can be a carboxylic acid having a double bond and a carbon number of 3 to 8. Preferably, the unsaturated carboxylic acid is acrylic acid (AA) and / or methacrylic acid (MAA).

[0063] In some embodiments, the mass ratio of the polyether macromonomer to the unsaturated carboxylic acid can be 200:(10 to 25), such as 200:10, 200:11, 200:12, 200:13, 200:15, 200:18, 200:20, 200:22, 200:25, etc.

[0064] In the present application, the temperature of the polymerization reaction can be 5 to 40°C, such as 5°C, 7°C, 8°C, 10°C, 15°C, 25°C, 30°C, 33°C, 35°C, 40°C, etc. In some embodiments, the temperature of the polymerization reaction can be controlled within any temperature range within the above range, such as between 10 to 40°C, between 13 to 25°C, between 15 to 30°C, etc.

[0065] In the present application, the time of the polymerization reaction can be determined according to the conversion degree of the reactants, and can generally be 2 to 6h, such as 2h, 3.5h, 5h, 6h, etc.

[0066] In the present application, the initiator can be selected from various water-soluble initiators, such as one or more of redox system initiators, persulfate initiators (such as ammonium persulfate), peroxide initiators (such as tert-butyl hydroperoxide), and preferably the initiator is a redox system initiator. The redox system initiator includes an oxidizing agent and a reducing agent.

[0067] As some preferred examples, the oxidizing agent is selected from at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, dibenzoyl peroxide, and tert-butyl hydroperoxide. Among them, hydrogen peroxide can generally be used in the form of hydrogen peroxide water, and the mass content of hydrogen peroxide in the hydrogen peroxide water can be, for example, 27.5%.

[0068] As some preferred examples, the reducing agent is selected from at least one of L-ascorbic acid, azobisimidoform hydrochloride, sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium dithionite, ferrous sulfate, sodium hypophosphite, sodium phosphite, and ferrous ammonium sulfate.

[0069] In the present application, the mass ratio of the oxidizing agent to the initiator can be 1:(0.1 to 2), such as 1:0.3, 1:0.4, 1:0.5, 1:0.7, 1:0.8, 1:1, 1:1.2, 1:1.3, 1:1.6, 1:1.8, etc.

[0070] In some embodiments, the mass amount of the initiator can be 0.1% to 2% of the mass of the polyether macro-monomer, such as 0.1%, 0.2%, 0.3%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, etc.

[0071] In the present application, the chain transfer agent can be selected from various water-soluble chain transfer agents for radical polymerization. As some preferred examples, the chain transfer agent is selected from at least one of mercaptoethanol, mercaptoacetic acid, mercapto-propanol, mercapto-propanoic acid, trisodium phosphate, sodium formate, and sodium acetate.

[0072] In some embodiments, the mass amount of the chain transfer agent can be 0.2% to 2% of the mass of the polyether macro-monomer, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, etc.

[0073] In the present application, in order to improve the stability of the water-reducing agent and the workability of the concrete, preferably, the preparation method of the polycarboxylic acid water-reducing agent comprises the following steps (1) and (2).

[0074] Step (1): dissolving the polyether macro-monomer, the functional monomer, and the oxidizing agent in water to obtain a bottom solution, under the conditions of stirring and a temperature of 5-40°C, adding A solution to the bottom solution dropwise, after 1-10 min of A solution dropwise addition, starting B solution dropwise addition, after 1-10 min of B solution dropwise addition, starting C solution dropwise addition; wherein,

[0075] The A solution is an aqueous solution of the unsaturated carboxylic acid, the dropwise addition time of A solution is t1, t1 is 1.0-2.5 h, such as 1 h, 1.5 h, 2 h, etc.

[0076] The B solution is a mixed aqueous solution of the reducing agent and the chain transfer agent, the dropwise addition time of B solution is t2, t2 is 1.5-3 h, such as 1.5 h, 2 h, etc.

[0077] The C solution is an aqueous solution of the unsaturated amide, the dropwise addition time of C solution is t3, t3 is 1.0-2.5 h, such as 1 h, 1.5 h, etc.

[0078] In step (1), by controlling the dropwise addition order and time of different materials, the connection order of the molecular chain structure units of the polycarboxylic acid can be regulated, and the formation of copolymerization products with differentiated molecular structures can be promoted.

[0079] Step (2): after the dropwise addition of the C solution is completed, continue to react for 0.5-2 h, such as 0.5 h, 1 h, etc. In this way, the conversion rate of the copolymerization monomers can be further improved.

[0080] Optionally, the preparation method further comprises,

[0081] Step (3), neutralizing the product obtained in step (2) with a base to make the pH value 6-7. Specific examples of the base include, but are not limited to, sodium hydroxide. The base is preferably in the form of a lye.

[0082] In the present application, the amount of water used can make the solid content of the prepared polycarboxylic acid water reducer 40%-60%, for example, 45%, 48%, 49%, 50%, 55%, 56%, 58%, 60%, etc.

[0083] The second aspect of the present application provides a polycarboxylic acid water reducer prepared by the preparation method of the first aspect of the present application.

[0084] The third aspect of the present application provides the use of the polycarboxylic acid water reducer of the second aspect of the present application in building materials. The polycarboxylic acid water reducer of the present application has a high viscosity-reducing effect on building materials, especially on concrete, and can promote the rapid dispersion of concrete and improve its workability.

[0085] The following describes an embodiment of the present application. The following described embodiment is exemplary and is only used to explain the present application and cannot be understood as a limitation of the present application.

[0086] The following preparation examples are used to illustrate the functional monomers used in the examples and comparative examples and their preparation methods.

[0087] Preparation Example 1

[0088] Rhamnolipid (monosaccharide monoester, m=6), unsaturated alcohol (2-methyl-3-buten-1-ol), catalyst (benzenesulfonic acid) and polymerization inhibitor (hydroquinone) were added to the reactor, the molar ratio of rhamnolipid to unsaturated alcohol was 1:1.1, the amount of catalyst was 2.0% of the total mass of rhamnolipid and unsaturated alcohol, and the amount of polymerization inhibitor was 1.0% of the total mass of rhamnolipid and unsaturated alcohol. Under nitrogen protection, the temperature was raised to 85°C and kept constant under stirring for 5h, during which water was removed by vacuum pumping. After the reaction was completed, it was naturally cooled to room temperature to obtain the esterification product (i.e. functional monomer), which is denoted as A1.

[0089] Preparation Examples 2-4

[0090] The functional monomers were prepared according to the method of Preparation Example 1, except that the types of reactants were replaced as shown in Table 1, and the prepared functional monomers were denoted as A2, A3, A4, respectively.

[0091] Table 1

[0092]

[0093] In the following examples and comparative examples, the concentration of H2O2 in the hydrogen peroxide is 27.5%. Unless otherwise specified, parts refer to parts by weight, and the water used is deionized water. The interval time between different solutions refers to the time interval between the start of the addition of the previous solution and the start of the addition of the subsequent solution.

[0094] Example 1

[0095] Into a reaction vessel were added 200 parts of ethylene glycol monovinyl polyethylene glycol ether (EPEG-3000), 2 parts of functional monomer A1, 1.0 part of hydrogen peroxide, and 120 parts of water, and the mixture was stirred until uniform. The temperature was controlled at 15°C, and under these conditions, A solution (12.0 parts of acrylic acid, 10.0 parts of water), B solution (0.5 parts of ascorbic acid, 1.5 parts of mercaptoethanol, 15.0 parts of water), and C solution (0.6 parts of N-hydroxymethyl acrylamide, 15.0 parts of water) were sequentially added dropwise to the reaction vessel. The B solution was added dropwise with an interval of 5 min from the A solution, and the C solution was added dropwise with an interval of 10 min from the B solution. The A solution was added dropwise for 1 h, the B solution was added dropwise for 1.5 h, and the C solution was added dropwise for 1 h. After the addition of the C solution was completed, the mixture was stirred for an additional 0.5 h. The pH was adjusted to 6-7 by adding a base, and the solid content was adjusted with water to obtain a polycarboxylate superplasticizer having a solid content of 50%, which was designated as PCE-1.

[0096] Example 2

[0097] Into a reaction vessel were added 200 parts of isopentenyl alcohol polyoxyethylene ether (TPEG-2400), 1 part of functional monomer A2, 1.0 part of hydrogen peroxide, and 120 parts of water, and the mixture was stirred until uniform. The temperature was controlled at 30°C, and under these conditions, A solution (20.0 parts of methacrylic acid, 10.0 parts of water), B solution (1 part of sodium bisulfite, 0.8 parts of mercaptoacetic acid, 15.0 parts of water), and C solution (1 part of 2-acrylamide-2-methylpropane sulfonic acid, 15.0 parts of water) were sequentially added dropwise to the reaction vessel. The B solution was added dropwise with an interval of 5 min from the A solution, and the C solution was added dropwise with an interval of 10 min from the B solution. The A solution was added dropwise for 1.5 h, the B solution was added dropwise for 1.5 h, and the C solution was added dropwise for 1 h. After the addition was completed, the mixture was stirred for an additional 1 h. The pH was adjusted to 6-7 by adding a base, and the solid content was adjusted with water to obtain a polycarboxylate superplasticizer having a solid content of 50%, which was designated as PCE-2.

[0098] Example 3

[0099] Into a reaction vessel were added 200 parts of methyl allyl alcohol polyoxyethylene ether (HPEG-2400), 0.8 parts of functional monomer A3, 2.0 parts of hydrogen peroxide, and 120 parts of water, and stirred to homogeneity. The temperature was controlled at 20°C. Under this condition, A solution (12.0 parts of acrylic acid, 10.0 parts of water), B solution (0.5 parts of hydrazine hydrate, 1.5 parts of mercaptopropionic acid, 15.0 parts of water), and C solution (0.6 parts of methacrylamide, 15.0 parts of water) were sequentially added dropwise into the reaction vessel for reaction. B solution was added dropwise with an interval of 5 min from A solution, and C solution was added dropwise with an interval of 10 min from B solution. The dropping time of A solution was 1 h, the dropping time of B solution was 1.5 h, and the dropping time of C solution was 1 h. After the dropping was completed, the reaction was continued for 1 h. The pH was adjusted to 6-7 by adding alkali, and the solid content was adjusted with water to obtain a polycarboxylate superplasticizer with a solid content of 50%, which was recorded as PCE-3.

[0100] Example 4

[0101] Into a reaction vessel were added 200 parts of TPEG-2400, 1.5 parts of functional monomer A4, 1.0 parts of hydrogen peroxide, and 120 parts of water, and stirred to homogeneity. The temperature was controlled at 30°C. Under this condition, A solution (22.0 parts of acrylic acid, 10.0 parts of water), B solution (1 part of sodium bisulfite, 1 part of mercaptoacetic acid, 17.0 parts of water), and C solution (0.2 parts of acrylamide, 0.2 parts of methacrylamide, 15.0 parts of water) were sequentially added dropwise into the reaction vessel for reaction. B solution was added dropwise with an interval of 5 min from A solution, and C solution was added dropwise with an interval of 5 min from B solution. The dropping time of A solution was 1.5 h, the dropping time of B solution was 1.5 h, and the dropping time of C solution was 1 h. After the dropping was completed, the reaction was continued for 1 h. The pH was adjusted to 6-7 by adding alkali, and the solid content was adjusted with water to obtain a polycarboxylate superplasticizer with a solid content of 50%, which was recorded as PCE-4.

[0102] Comparative Example 1

[0103] A polycarboxylate superplasticizer was prepared according to the method of Example 1, except that no functional monomer A1 was added, and the solid content was adjusted to 50% by adjusting the amount of water to obtain a polycarboxylate superplasticizer, which was recorded as PCE-D1.

[0104] Comparative Example 2

[0105] A polycarboxylate superplasticizer was prepared according to the method of Example 1, except that no acrylamide was added, and the solid content was adjusted to 50% by adjusting the amount of water to obtain a polycarboxylate superplasticizer, which was recorded as PCE-D2.

[0106] Comparative Example 3

[0107] The polycarboxylic water reducer was prepared according to the method of Example 1, except that no functional monomers A1 and C solution was added, and the solid content of the polycarboxylic water reducer was adjusted to 50% by adjusting the amount of water, and was recorded as PCE-D3.

[0108] Test Example

[0109] 1. Storage stability analysis

[0110] The water reducer was stored at room temperature for 6 months, and the odor and appearance of the water reducer were observed during the storage. If there was neither mold nor odor, the result was recorded as "no". If there was odor and / or mold, the result was recorded as "yes". The test results are shown in Table 2.

[0111] Table 2

[0112]

[0113]

[0114] As can be seen from Table 2, compared with Comparative Examples 1-3, the polycarboxylic water reducer prepared in Examples 1-4 has higher storage stability.

[0115] 2. Application performance test

[0116] The water reducer was tested for water reducing rate and its effect on freshly mixed high-strength concrete according to the method specified in GB 8076-2008 "Concrete Admixtures" using Runfeng cement (P·O42.5):

[0117] The slump and spread of the freshly mixed high-strength concrete were tested at 30s, 60s and 120s after mixing;

[0118] The emptying time of the inverted slump cone at 60s and 120s after mixing was tested to quantify the viscosity of the concrete, and the shorter the emptying time, the smaller the viscosity of the concrete;

[0119] The state of the concrete was observed during mixing, and when the concrete showed fast flow rate, no bleeding, no slurry running, no stone leakage and other phenomena, it was considered to have "good workability". When at least one of the phenomena such as slow flow rate, bleeding, slurry running, black cap, piling or stone leakage occurred, it was considered to have "poor workability".

[0120] The mix proportion of the concrete was: cement 430 kg / m 3 , fly ash 30 kg / m 3 , slag 90 kg / m 3 , sand 700 kg / m 3 , stone 1050 kg / m 3 , water 155 kg / m 3 .

[0121] The experimental environment temperature was 5℃, and the test results are shown in Table 3.

[0122] Table 3

[0123]

[0124]

[0125] From the data in Table 3, it can be seen that the poly-carboxylic acid water reducing agent prepared in Examples 1-4 has little difference in the spread degree at each stirring time of 30s, 60s and 120s, which indicates that the water reducing agent prepared in Examples 1-4 can realize rapid dispersion, and the slump loss emptying time is also short, which shows that the viscosity of the concrete can be effectively reduced, and the workability of the concrete is good.

[0126] In combination with the data in Tables 2 and 3, it can be seen from the comparison between Example 1 and Comparative Examples 1-3 that, when no functional monomer is used (Comparative Example 1), the storage stability of the prepared water reducing agent without modification by glycolipid is poor, and the dispersion speed thereof is slow in a low temperature environment, the concrete is prone to lag amplification, and the state of segregation and bleeding is easy to appear and lagging bleeding phenomenon is easy to appear; when no unsaturated amide monomer is used (Comparative Example 2), the slump retention performance of the water reducing agent is affected; when only polyether macromonomer and acrylic acid are copolymerized (Comparative Example 3), the dispersion efficiency of the formed water reducing agent on the concrete is not high, and bleeding is serious.

[0127] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. Especially, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for producing a polycarboxylate water reducer, characterized by, The preparation method comprises: polymerizing comonomers including a polyether macromonomer, an unsaturated carboxylic acid, an unsaturated amide and a functional monomer in the presence of water, an initiator and a chain transfer agent to form a polycarboxylic acid; wherein the functional monomer is an esterification product of rhamnolipid and an unsaturated alcohol, and the mass ratio of the polyether macromonomer, the unsaturated carboxylic acid, the unsaturated amide and the functional monomer is 200:(10-25):(0.2-2):(0.5-2).

2. The production method according to claim 1, characterized by, The rhamnolipid has any one of Formula 1-1 to Formula 1-4: wherein m and n are independently any integer from 1 to 10.

3. The preparation method according to claim 1, characterized in that, The structure of the unsaturated alcohol is shown in Formula 2: Formula 2, In Formula 2, L represents a substituted or unsubstituted linear alkylene group with 1-4 carbon atoms, and the substituent is methoxy or methyl.

4. The method of claim 1, wherein, The unsaturated alcohol is selected from one or more of 2-methyl-3-buten-1-ol, 2-methyl-2-propen-1-ol and 2-methoxy-3-buten-1-ol.

5. The method of any one of claims 1-4, wherein, The functional monomer is prepared by esterifying the rhamnolipid and the unsaturated alcohol under the protection of inert gas in the presence of a catalyst and a polymerization inhibitor.

6. The production method according to claim 5, characterized by, The molar ratio of the rhamnolipid to the unsaturated alcohol is 1:(1-2).

7. The preparation method according to claim 5, characterized in that, The catalyst is at least one of benzenesulfonic acid, p-toluenesulfonic acid and ethyl sulfonic acid.

8. The preparation method according to claim 5, characterized in that, The mass amount of the catalyst is 0.5%-5% of the total mass of the rhamnolipid and the unsaturated alcohol.

9. The preparation method according to claim 5, characterized in that, The polymerization inhibitor is at least one of hydroquinone, phenothiazine and diphenylamine.

10. The method of claim 5, wherein, The mass amount of the polymerization inhibitor is 0.3%-3% of the total mass of the rhamnolipid and the unsaturated alcohol.

11. The method of claim 5, wherein, The temperature of the esterification reaction is 70-90°C, and the reaction time is 3-8 hours.

12. The method of any one of claims 1-4, wherein, The temperature of the polymerization reaction is 5-40°C, and the reaction time is 2-6 hours.

13. The method of any one of claims 1-4, wherein, The polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether, methyl allyl alcohol polyoxyethylene ether, ethylene glycol monovinyl polyethylene glycol ether and 4-hydroxybutyl vinyl polyoxyethylene ether.

14. The method of any one of claims 1-4, wherein, The unsaturated carboxylic acid is acrylic acid and / or methacrylic acid.

15. The method of any one of claims 1-4, wherein, The unsaturated amide is at least one of acrylamide, methacrylamide, N-hydroxymethyl acrylamide and 2-acrylamide-2-methylpropane sulfonic acid.

16. The method of any one of claims 1-4, wherein, The chain transfer agent is at least one of mercaptoethanol, mercaptoacetic acid, mercaptopropanol, mercaptopropanoic acid, trisodium phosphate, sodium formate and sodium acetate.

17. The method of making according to any one of claims 1-4, wherein, The mass amount of the chain transfer agent is 0.2%-2% of the mass of the polyether macromonomer.

18. The method of making according to any one of claims 1-4, wherein, The initiator is a redox initiator.

19. The method of claim 18, wherein, The oxidizing agent in the redox initiator is at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, cumene hydroperoxide, dibenzoyl peroxide and tert-butyl hydroperoxide; The reducing agent in the redox initiator is at least one of L-ascorbic acid, azobisimidozolinium chloride, sodium bisulfite, sodium sulfite, sodium metabisulfite, sodium sulfite, ferrous sulfate, sodium hypophosphite, sodium phosphite and ferrous ammonium sulfate.

20. The method of claim 19, wherein, The mass ratio of the oxidizing agent to the reducing agent is 1:(0.1-2).

21. The method of any one of claims 1-4, wherein, The mass amount of the initiator is 0.1%-2% of the mass of the polyether macromonomer.

22. The preparation method according to claim 19, characterized in that, The preparation method comprises the following steps: (1) dissolving the polyether macro-monomer, functional monomer and oxidant in water to obtain a bottom solution, under stirring and at a temperature of 5-40℃, adding A solution to the bottom solution dropwise, after 1-10 min of A solution dropwise addition, starting B solution dropwise addition, after 1-10 min of B solution dropwise addition, starting C solution dropwise addition; wherein, the A solution is an aqueous solution of the unsaturated carboxylic acid, the A solution dropwise addition time is t1; the B solution is a mixed aqueous solution of the reducing agent and chain transfer agent, the B solution dropwise addition time is t2; the C solution is an aqueous solution of the unsaturated amide, the C solution dropwise addition time is t3; t1 is 1.0-2.5 h, t2 is 1.5-3 h, t3 is 1.0-2.5 h, (2) after all solution dropwise addition is completed, continuing to react for 0.5-2 h; Optionally, the preparation method further comprises: (3) adjusting the pH of the product obtained in step (2) to 6-7 by a base.

23. The method of any one of claims 1-4, wherein, The water is used in an amount such that the solid content of the prepared polycarboxylic acid water reducer is 40%-60%.

24. A polycarboxylic acid water reducer prepared by the preparation method of any one of claims 1-23.

25. Use of the polycarboxylic acid water reducer of claim 24 in building materials.

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