Slump-retaining polycarboxylate superplasticizer as well as preparation method and application thereof
By performing copolymerization reaction in water, a polycarboxylic acid water reducing agent with functional monomer I and functional monomer II is prepared, which solves the problem of poor slump retention of existing water reducing agents during long-distance transportation, achieves a longer slump retention time and a higher water reducing effect, and reduces the cost of concrete use.
Patent Information
- Application Number
- CN202411971399.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-05-09
Smart Images
Figure BDA0005219574080000161
Abstract
Description
Technical Field
[0001] The invention belongs to the field of admixtures and provides a collapse-retaining polycarboxylic acid water-reducing agent and a preparation method and application thereof. Background Art
[0002] Concrete is a cementitious composite material formed by cement, sandstone, steel bars and other reinforcing materials. Due to its low price, wide source and easy construction, concrete has always been a major building material and is widely used in buildings such as buildings, roads and bridges. With the rapid development of the construction industry, the quality requirements for concrete are getting higher and higher. Among them, the slump retention of concrete is of great significance to the promotion and application of commercial concrete, because commercial concrete needs to meet the construction slump requirements after being transported to the construction site for a long time, which puts higher requirements on the slump retention performance of admixtures.
[0003] At present, the slump-retaining polycarboxylic acid water-reducing agent on the market has a single ingredient, a high dosage during use, and the carboxyl group is released too quickly. During long-distance transportation, the slump-retaining property of the water-reducing agent is poor, usually only retaining the slump for 1 to 2 hours, and it is highly sensitive to materials (prone to concrete segregation, poor fluidity, etc.), resulting in excessively high costs for concrete during use, limiting the application of concrete. Summary of the invention
[0004] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a collapse-preserving polycarboxylate water-reducing agent and a preparation method and application thereof. The collapse-preserving polycarboxylate water-reducing agent prepared by the present invention has improved water-reducing effect and a longer collapse-preserving time.
[0005] In a first aspect, the present invention provides a method for preparing a collapse-retaining polycarboxylic acid water-reducing agent, the method comprising: polymerizing a comonomer including a functional monomer I, a polyether macromonomer, a functional monomer II, an unsaturated carboxylic acid and an unsaturated silane coupling agent I in water to form a polycarboxylic acid; wherein:
[0006] The functional monomer I is prepared by esterifying graphene oxide and diphenylhydroxyacetic acid and then grafting an unsaturated silane coupling agent II; the functional monomer II is hydroxyethyl acrylate and hydroxypropyl methacrylate.
[0007] In the method of the present invention, functional monomer I and functional monomer II are copolymerized with monomers such as unsaturated carboxylic acid and polyether macromonomer, and the synergistic effect of the monomers enables the prepared polycarboxylic acid water-reducing agent to slowly release carboxyl groups during use, thereby improving the workability of concrete and prolonging the slump retention time while maintaining a high water-reducing effect and a low air content. On the one hand, in the functional monomer I used, graphene oxide (GO) is esterified with diphenyl glycolic acid, and diphenyl is introduced on the surface of GO. Under the condition of maintaining the strength of concrete, the water-reducing effect can be improved. The unsaturated silane coupling agent is used for grafting modification, and the carboxyl group can be protected and an unsaturated double bond can be introduced, so that the modified graphene oxide can be introduced into the polycarboxylic acid molecular chain as a monomer through copolymerization, thereby improving the dispersion uniformity and stability of graphene oxide in the water reducer. The chain segment provided by the functional monomer I on the polycarboxylic acid molecular chain can ensure the slow release of the carboxyl group during long-distance transportation, and prevent the occurrence of slurry bleeding in the middle period; the functional monomer II is a combination of hydroxyethyl acrylate and hydroxypropyl methacrylate, which can improve the dispersion performance of the water reducer during concrete mixing and prevent the occurrence of reverse increase in concrete slump retention.
[0008] In some embodiments of the present invention, the functional monomer I is prepared by a method comprising the following steps: in the presence of an organic solvent and a catalyst, diphenylhydroxyacetic acid and graphene oxide are subjected to an esterification reaction under heating and reflux conditions to form modified graphene oxide; the unsaturated silane coupling agent II is pre-hydrolyzed in an aqueous solvent, and then the modified graphene oxide is added for a grafting reaction to form the functional monomer I.
[0009] In some embodiments of the present invention, relative to 100 parts by weight of the polyether macromonomer, the amount of the functional monomer I is 1 to 8 parts by weight, the amount of the functional monomer II is 1 to 10 parts by weight, the amount of the unsaturated carboxylic acid is 1 to 5 parts by weight, and the amount of the unsaturated silane coupling agent I is 0.01 to 0.5 parts by weight.
[0010] In some embodiments of the present invention, the preparation method comprises the following steps:
[0011] S1: Provide reaction solution A, reaction solution B and reaction solution C respectively
[0012] The unsaturated carboxylic acid, the unsaturated silane coupling agent I and the functional monomer I are uniformly mixed with water to obtain the reaction solution A;
[0013] Dissolving the functional monomer II in water to obtain the reaction solution B;
[0014] Dissolving the chain transfer agent and the reducing agent in water to obtain the reaction solution C;
[0015] S2: dissolving the polyether macromonomer and the oxidant in water to obtain a base solution;
[0016] At 5-45°C, the reaction solution A and the reaction solution C are added dropwise to the base solution for a time of t1 and a time of t2. 11 When the reaction liquid B is added dropwise, the addition time of the reaction liquid B is controlled to be t2, wherein;
[0017] t1 is 50 to 200 minutes, t 11 Satisfies the relationship with t1: t 11 =c×t1, c is 0.1~0.5,
[0018] t2 is 50 to 200 minutes.
[0019] In some embodiments of the present invention, the amount of water used is such that the solid content of the prepared collapse-retaining polycarboxylate water-reducing agent is 40% to 50%.
[0020] In a second aspect, the present invention provides a collapse-retaining polycarboxylate water-reducing agent prepared by the preparation method described in the first aspect of the present invention.
[0021] As described above, the collapse-preserving polycarboxylate water-reducing agent can improve the workability and collapse-preserving property of concrete. In addition, adding a small amount of the collapse-preserving polycarboxylate water-reducing agent to concrete can achieve a collapse-preserving effect of more than 3 hours, which has a relatively broad application prospect.
[0022] In a third aspect, the present invention provides use of the collapse-retaining polycarboxylate water-reducing agent described in the second aspect of the present invention in building materials.
[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION
[0024] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0025] The "range" disclosed in the present invention is defined in the form of a lower limit and / or an upper limit, and a given range is defined by selecting a lower limit and / or an upper limit. The range defined in this way can be inclusive or exclusive of the end value, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form an undefined range, and any lower limit can be combined with other lower limits to form an undefined range, and any upper limit can be combined with any other upper limit to form an undefined range. In addition, each separately disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an undefined range.
[0026] If not otherwise specified, all embodiments and optional embodiments of the present invention may 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 invention.
[0027] The first aspect of the present invention provides a method for preparing a collapse-retaining polycarboxylic acid water-reducing agent, comprising: polymerizing a copolymerization monomer including a functional monomer I, a polyether macromonomer, a functional monomer II, an unsaturated carboxylic acid and an unsaturated silane coupling agent I in water to form a polycarboxylic acid, thereby preparing the collapse-retaining polycarboxylic acid water-reducing agent.
[0028] In the present invention, the polyether macromonomer can be selected from various ether macromonomers having carbon-carbon double bonds. Preferably, the polyether macromonomer is selected from one or more of methyl allyl polyoxyethylene ether (HPEG), isopentenyl polyoxyethylene ether (TPEG) and ethylene glycol monovinyl polyoxyethylene ether (EPEG).
[0029] In the present invention, the average molecular weight (Mw) of the polyether macromonomer may be, for example, 3,000 to 6,000.
[0030] As some examples, the polyether macromonomer can be one or more of HPEG-3000, HPEG-5000, TPEG-5000, TPEG-6000, EPEG-3000, and EPEG-6000. The polyether macromonomer of the present invention can be prepared by methods well known in the art, or can be commercially available, such as a series of polyether products selected from Oak Chemical Co., Ltd.
[0031] In the present invention, the functional monomer I is graphene oxide modified by diphenyl glycolic acid and unsaturated silane coupling agent II, specifically prepared by esterification of graphene oxide and diphenyl glycolic acid and then grafting unsaturated silane coupling agent II. During the use of the water reducer, the chain segment provided by the functional monomer I protects the release of the carboxyl group in the late stage of collapse retention, and the benzene ring can provide a better water reduction effect.
[0032] In some embodiments, relative to 100 parts by weight of the polyether macromonomer, the amount of the functional monomer I can be 1 to 8 parts by weight, such as 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 7.5 parts by weight, etc. In this case, while maintaining the slump-retaining effect, the possibility of the phenomenon of the concrete being reversed in the later stage and the initial setting time being prolonged due to excessive dosage can be reduced.
[0033] In the present invention, the graphene oxide can be obtained commercially or prepared by methods well known in the art, for example, it can be prepared by the Hummers method. As some examples, the preparation method of the graphene oxide is as follows: in an ice water bath, under stirring conditions, 2g of graphite powder and 1g of sodium nitrate are added to a reaction vessel containing 70mL of concentrated sulfuric acid and mixed evenly, 6g of potassium permanganate is slowly added, the reaction temperature is controlled not to exceed 20°C, the reaction is stirred for 2h, and then the temperature is raised to about 35°C, and stirring is continued for 30min, and then deionized water is slowly added, stirred for 30min, and hydrogen peroxide is added to reduce the residual oxidant so that the solution becomes bright yellow, and filtered while hot, and washed with 5% HCL and deionized water until no sulfate is detected in the filtrate, and finally the filter cake is placed in a vacuum drying oven for drying to obtain graphene oxide. In addition, the oxygen content of the graphene oxide can generally be 25% to 30%, and the average thickness can be 0.5 to 2nm, for example 0.5nm.
[0034] In the present invention, the unsaturated silane coupling agent II can be various silane coupling agents with carbon-carbon double bonds. According to some embodiments, the unsaturated silane coupling agent II is selected from at least one of vinyl triethoxy silane and vinyl trimethoxy silane. Preferably, the unsaturated silane coupling agent II is vinyl triethoxy silane.
[0035] According to some specific embodiments, the functional monomer I is prepared by a method comprising the following steps:
[0036] (1) in the presence of an organic solvent and a catalyst, allowing diphenyl glycolic acid and graphene oxide to undergo an esterification reaction under heating and reflux conditions to form modified graphene oxide;
[0037] (2) The unsaturated silane coupling agent II is pre-hydrolyzed in a water-containing solvent, and then the modified graphene oxide is added to carry out a grafting reaction to form a functional monomer I.
[0038] In step (1), the esterification reaction is carried out under heating reflux conditions, which can improve the degree of reaction.
[0039] The present invention does not particularly limit the type of the organic solvent, as long as it can dissolve the diphenyl glycolic acid and the catalyst and achieve uniform dispersion of graphene oxide. For example, the organic solvent can be selected from one or more of the following organic solvents: xylene, chlorobenzene, and tetrachloroethylene. The mass ratio of the organic solvent to the diphenyl glycolic acid can be (10-30):1, such as 12:1, 15:1, 17:1, 18:1, 20:1, 22:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, etc.
[0040] As some preferred examples, the catalyst is one or more of triphenylphosphine, toluenesulfonic acid and thionyl chloride.
[0041] In step (1), the amount of the catalyst can be selected according to the amount of the graphene oxide. According to some embodiments, the mass amount of the catalyst is 2% to 15% of the mass of the graphene oxide, for example 2%, 3%, 4%, 5%, 6%, 8%, 9%, 10%, 12%.
[0042] In some embodiments, the mass ratio of diphenylglycolic acid to the graphene oxide can be (2-5):1, for example, 2:1, 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 5:1, etc.
[0043] In some embodiments, the temperature of the esterification reaction is 90-130°C, for example, 90°C, 95°C, 100°C, 104°C, 105°C, 110°C, 120°C, 125°C, 130°C, etc.; the time of the esterification reaction can be 2-6h, for example, 2h, 2.5h, 3h, 4h, 5h, 5.2h, 5.5h, 6h, etc.
[0044] Preferably, step (1) further comprises: after the esterification reaction, removing the organic solvent, washing the obtained product (for example, washing with a saturated sodium bicarbonate solution and a saturated sodium chloride solution in sequence), filtering, and drying to obtain high-purity modified graphene oxide. The drying may be, for example, vacuum drying at a drying temperature of 50 to 80°C.
[0045] In step (2), the alkoxy groups in the molecular structure of the unsaturated silane coupling agent II can be converted into hydroxyl groups by pre-hydrolysis, and the grafting modification is achieved by the reaction of the hydroxyl groups with the oxygen-containing functional groups on the modified graphene oxide.
[0046] In step (2), the aqueous solvent may be water or a mixed solvent of water and alcohol. As some preferred examples, the aqueous solvent is a mixed solvent of water and ethanol, and the mass proportion of ethanol in the mixed solvent may be 40% to 60%, such as 40%, 45%, 50%, 52%, 55%, 58%, 60%, etc.
[0047] As some examples, the mass ratio of the aqueous solvent to the unsaturated silane coupling agent II can be (1000-2000):1, for example, 1100:1, 1150:1, 1200:1, 1250:1, 1280:1, 1300:1, 1380:1, 1400:1, 1500:1, 1560:1, 1650:1, 1700:1, 1800:1, 1900:1, 2000:1, etc.
[0048] In some embodiments, the prehydrolysis temperature can be 30-50°C, for example, 30°C, 35°C, 40°C, 42°C, 45°C, 50°C, etc.; the prehydrolysis time can be 0.5-3h, for example, 1h, 1.5h, 2h, 3h, etc.
[0049] In some embodiments, the mass ratio of the unsaturated silane coupling agent II to the modified graphene oxide is 1:(0.5-2), for example, 1:0.5, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.5, 1:1.7, 1:1.8, 1:1.9, 1:2, etc.
[0050] In some embodiments, the grafting reaction temperature can be 60-80°C, for example, 60°C, 65°C, 70°C, 80°C, etc.; the grafting reaction time can be 2-8h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.
[0051] Generally, the grafting reaction can be carried out under stirring conditions.
[0052] Preferably, step (2) further comprises: after the grafting reaction is completed, solid-liquid separation, washing and vacuum drying are performed to obtain dry functional monomer I. The solid-liquid separation method includes, but is not limited to, filtration. Washing is performed using a mixed solvent of water and ethanol, and the mass ratio of water to ethanol can be 1: (0.8-1.2), for example, 1: 1.
[0053] In the present invention, the functional monomer II is hydroxyethyl acrylate (2-HEA) and hydroxypropyl methacrylate (HPMA). Preferably, the mass ratio of hydroxyethyl acrylate to hydroxypropyl methacrylate is 1:(1.2-2.5), for example, 1:1.5, 1:2, 1:2.1, 1:2.5, etc.
[0054] In some embodiments, relative to 100 parts by weight of the polyether macromonomer, the amount of the functional monomer II can be 1 to 10 parts by weight, for example, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, etc.
[0055] In the present invention, the unsaturated carboxylic acid may be a carboxylic acid having a double bond and carbon atoms of 3 to 8. Preferably, the unsaturated carboxylic acid is at least one of acrylic acid (AA) and methacrylic acid (MAA).
[0056] In some embodiments, the amount of the unsaturated carboxylic acid is 1 to 5 parts by weight relative to 100 parts by weight of the polyether macromonomer, for example, 1 part by weight, 1.5 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.5 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, etc.
[0057] In the present invention, the unsaturated silane coupling agent I can be selected from various silane coupling agents having double bonds. According to some embodiments, the unsaturated silane coupling agent I is vinyl triethoxy silane and / or vinyl trimethoxy silane.
[0058] In some embodiments, the amount of the unsaturated silane coupling agent I is 0.01 to 0.5 parts by weight relative to 100 parts by weight of the polyether macromonomer, for example, 0.01 parts by weight, 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, etc.
[0059] In the present invention, the polymerization temperature can be 5-50°C, such as 5°C, 8°C, 12°C, 15°C, 18°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc. In some embodiments, the polymerization temperature can be controlled within any temperature range within the above range, such as between 10-40°C, between 13-25°C, between 15-30°C, etc.
[0060] In the present invention, the polymerization reaction time can be determined according to the conversion degree of the reactants, and can generally be 2 to 10 hours, for example, 2 hours, 3.5 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.
[0061] As some preferred embodiments, the polymerization reaction is carried out in the presence of an initiator and a chain transfer agent.
[0062] In the present invention, the initiator can be selected from various water-soluble initiators, for example, it can be selected from one or more of redox initiators, persulfate initiators (such as ammonium persulfate), peroxide initiators (such as tert-butyl hydroperoxide), and preferably the initiator is a redox initiator.
[0063] In the present invention, the redox initiator comprises an oxidizing agent and a reducing agent.
[0064] As some preferred examples, the oxidizing agent is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate; the reducing agent is selected from at least one of sodium bisulfite, vitamin C and sodium hypophosphite.
[0065] In the present invention, the mass ratio of the oxidant to the reductant may be 1:(0.1-0.8), for example, 1:0.3, 1:0.5, 1:0.7, 1:0.8, etc.
[0066] In the present invention, the hydrogen peroxide in the initiator can usually be used in the form of hydrogen peroxide. The mass content of hydrogen peroxide in the hydrogen peroxide can be, for example, 27.5%.
[0067] In some embodiments, the mass dosage of the initiator can be 0.1% to 2% of the total mass of the comonomer (i.e., the total mass of the polyether macromonomer, functional monomer I, functional monomer II, unsaturated carboxylic acid and unsaturated silane coupling agent I), for example, 0.1%, 0.2%, 0.3%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.2%, 1.4%, 1.5%, 1.8%, etc.
[0068] In the present invention, the chain transfer agent can be selected from various water-soluble chain transfer agents for free radical polymerization. As some preferred examples, the chain transfer agent is selected from at least one of mercaptopropionic acid, thioglycolic acid, mercaptoethanol, sodium formate and sodium hypophosphite.
[0069] In some embodiments, the mass dosage of the chain transfer agent is 0.05% to 1% of the total mass of the comonomer, for example, 0.05%, 0.08%, 0.10%, 0.15%, 0.2%, 0.3%, 0.5%, 0.53%, 0.6%, 0.8%, etc.
[0070] According to some preferred embodiments, the method for preparing the collapse-retaining polycarboxylic acid comprises the following steps:
[0071] S1: Provide reaction solution A, reaction solution B and reaction solution C respectively
[0072] The unsaturated carboxylic acid, the unsaturated silane coupling agent I and the functional monomer I are uniformly mixed with water to obtain the reaction solution A;
[0073] Dissolving the functional monomer II in water to obtain the reaction solution B;
[0074] Dissolving the chain transfer agent and the reducing agent in water to obtain the reaction solution C;
[0075] S2: dissolving the polyether macromonomer I and the oxidant in water to obtain a base solution;
[0076] At 5-45° C., reaction solution A and reaction solution C are added dropwise to the base solution for a time of t1, and the reaction solution A and reaction solution C are added dropwise for a time of t 11 When the reaction liquid B is added dropwise, the addition time of the reaction liquid B is controlled to be t2, wherein;
[0077] t1 is 50 to 200 minutes, t 11 Satisfies the relationship with t1: t 11 =c×t1, c is 0.1~0.5,
[0078] t2 is 50 to 200 minutes.
[0079] In step S1, the mass content of water in the base liquid may be, for example, 40% to 70%.
[0080] As some examples, the dropwise addition time t1 of the reaction solution A and the reaction solution C may be 60 to 180 minutes, such as 60 minutes, 80 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and the like.
[0081] As some examples, the dropwise addition time t2 of the reaction solution B can be 50 to 180 minutes, such as 50 minutes, 80 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, etc.
[0082] In some embodiments, the amount of water used is such that the solid content of the prepared collapse-retaining polycarboxylate water-reducing agent is 40% to 50%, for example, 40%, 42%, 45%, 46%, 47%, 48%, 49%, 50%, etc.
[0083] The second aspect of the present invention provides a collapse-retaining polycarboxylate water-reducing agent prepared by the preparation method described in the first aspect of the present invention.
[0084] The third aspect of the present invention provides the use of the collapse-preserving polycarboxylate water-reducing agent described in the second aspect of the present invention in building materials. The collapse-preserving polycarboxylate water-reducing agent of the present invention has a high collapse-preserving effect on building materials, especially concrete.
[0085] The following embodiments of the present invention are described. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Unless otherwise specified, the parts hereinafter refer to parts by weight.
[0086] The following preparation examples are used to illustrate the functional monomer I and its preparation method used in the examples and comparative examples.
[0087] Preparation Example 1
[0088] 15 parts of diphenylhydroxyacetic acid and 0.3 parts of triphenylphosphine were dissolved in 400 parts of xylene, and 3 parts of graphene oxide were added and dispersed evenly. The resulting reaction solution was placed in a 1L flask, heated to 100°C and condensed and refluxed for 3 hours under stirring conditions of 350r / min, and then xylene was removed by distillation. The resulting product was washed and filtered with a saturated sodium bicarbonate solution and a saturated sodium chloride solution in turn, and vacuum dried at 60°C to obtain modified graphene oxide.
[0089] 350 parts of ethanol and 350 parts of water were mixed evenly, 0.4 parts of vinyltriethoxysilane was added to dissolve, and then placed in a 40°C water bath, and pre-hydrolyzed at 350 r / min for 1 hour. Then 0.2 parts of modified graphene oxide were added, the temperature was raised to 70°C and stirred for 3 hours. After the reaction was completed, it was cooled to room temperature. The obtained product was filtered, washed with ethanol aqueous solution (ethanol concentration was 50wt%), and vacuum dried at 60°C to obtain functional monomer I, which was recorded as GO-1.
[0090] Preparation Example 2
[0091] 20 parts of diphenylhydroxyacetic acid and 0.2 parts of triphenylphosphine were dissolved in 300 parts of xylene, and 5 parts of graphene oxide were added and dispersed evenly. The resulting reaction solution was placed in a 1L flask, heated to 100°C and condensed under reflux for 5 hours under stirring conditions of 400r / min, and then the xylene was removed by distillation. The resulting product was washed and filtered with a saturated sodium bicarbonate solution and a saturated sodium chloride solution in turn, and dried in vacuo at 60°C to obtain modified graphene oxide.
[0092] 350 parts of ethanol and 350 parts of water were mixed evenly, 0.6 parts of vinyltriethoxysilane was added to dissolve, and then placed in a 30°C water bath, pre-hydrolyzed at 300r / min for 1.5h, and then 0.4 parts of modified graphene oxide were added. The temperature was raised to 60°C and stirred for 3h. After the reaction was completed, it was cooled to room temperature. The product was filtered, washed with ethanol aqueous solution (ethanol concentration was 50wt%), and vacuum dried at 60°C to obtain functional monomer I, which was recorded as GO-2.
[0093] Preparation Example 3
[0094] 25 parts of diphenylhydroxyacetic acid and 0.6 parts of triphenylphosphine were dissolved in 500 parts of xylene, and 10 parts of graphene oxide were added and dispersed evenly. The resulting reaction solution was placed in a 1L flask, heated to 100°C and condensed under reflux for 5 hours under stirring conditions of 350 / min, and then xylene was removed by distillation. The resulting product was washed and filtered with a saturated sodium bicarbonate solution and a saturated sodium chloride solution in turn, and dried in vacuo at 50°C to obtain modified graphene oxide.
[0095] 350 parts of ethanol and 400 parts of water were mixed evenly, 0.3 parts of vinyltriethoxysilane was added to dissolve, and then placed in a 35°C water bath, and pre-hydrolyzed at 350 r / min for 1 hour. Then 0.6 parts of modified graphene oxide were added, the temperature was raised to 70°C and stirred for 2 hours. After the reaction was completed, it was cooled to room temperature. The obtained product was filtered, washed with ethanol aqueous solution (ethanol concentration was 50wt%), and vacuum dried at 55°C to obtain functional monomer I, which was recorded as GO-3.
[0096] Comparative Preparation Example 1
[0097] 350 parts of ethanol and 350 parts of water were mixed evenly, 0.4 parts of vinyltriethoxysilane was added to dissolve, and then placed in a 40°C water bath, and pre-hydrolyzed at 350 r / min for 1 hour. Then 0.2 parts of graphene oxide were added, the temperature was raised to 70°C and stirred for 3 hours. After the reaction was completed, it was cooled to room temperature. The product was filtered, washed with ethanol aqueous solution (ethanol concentration was 50wt%), and vacuum dried at 60°C to obtain unsaturated siloxane-modified graphene oxide, which was recorded as GO-d1.
[0098] In the following examples and comparative examples, the concentration of H2O2 in hydrogen peroxide is 27.5%.
[0099] Example 1
[0100] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0101] Add 5 parts of acrylic acid, 0.2 parts of vinyl triethoxysilane, and 5 parts of functional monomer I (GO-1) into 30 parts of water and stir evenly to obtain reaction solution A;
[0102] 10 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2) were added to 10 parts of water and stirred until uniformly dissolved to obtain reaction solution B;
[0103] 0.5 parts of mercaptopropionic acid and 0.3 parts of vitamin C were added into 20 parts of water and stirred until they were uniformly dissolved to obtain reaction solution C.
[0104] 2) Polymerization reaction
[0105] 200 parts of HPEG-3000 and 1.3 parts of hydrogen peroxide were added to a reactor containing 197 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 70 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 20°C. After the addition was completed, the reaction was continued at 20°C for 2 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-1.
[0106] Example 2
[0107] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0108] 3 parts of acrylic acid, 0.3 parts of vinyl triethoxysilane, and 8 parts of functional monomer I (GO-2) were added to 40 parts of water and stirred evenly to obtain a reaction solution A;
[0109] 7 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2) were added to 8 parts of water and stirred until uniformly dissolved to obtain reaction solution B;
[0110] 0.5 parts of mercaptopropionic acid, 0.1 parts of vitamin C and 0.2 parts of sodium hypophosphite were added to 20 parts of water and stirred until dissolved uniformly to obtain reaction solution C.
[0111] 2) Polymerization reaction
[0112] 200 parts of TPEG-5000 and 1.5 parts of hydrogen peroxide were added to a reactor containing 200 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 100 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 60 minutes. During the entire dropping process, the temperature of the reaction system was controlled to be 25°C. After the addition was completed, the reaction was continued at 25°C for 2.5 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-2.
[0113] Example 3
[0114] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0115] 7 parts of acrylic acid, 0.5 parts of vinyl triethoxysilane, and 10 parts of functional monomer I (GO-3) were added to 20 parts of water and stirred evenly to obtain a reaction solution A;
[0116] Add 3 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2) into 10 parts of water and stir until dissolved uniformly to obtain reaction solution B;
[0117] 0.4 parts of thioglycolic acid, 0.1 parts of sodium methyl propylene sulfonate and 0.4 parts of sodium bisulfite were added to 20 parts of water and stirred until they were uniformly dissolved to obtain a reaction solution C.
[0118] 2) Polymerization reaction
[0119] 100 parts of TPEG-6000, 100 parts of EPEG-6000 and 1.4 parts of hydrogen peroxide were added to a reactor containing 200 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 180 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 180 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 45°C. After the addition was completed, the reaction was continued at 45°C for 3 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-3.
[0120] Example 4
[0121] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0122] 8 parts of acrylic acid, 0.3 parts of vinyl triethoxysilane, and 8 parts of functional monomer I (GO-1) were added to 200 parts of water and stirred until uniformly dissolved to obtain reaction solution A;
[0123] 8 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:1.5) were added to 10 parts of water and stirred until uniformly dissolved to obtain reaction solution B;
[0124] 0.6 parts of thioglycolic acid and 0.5 parts of sodium bisulfite were added to 20 parts of water and stirred until they were uniformly dissolved to obtain a reaction solution C.
[0125] 2) Polymerization reaction
[0126] 200 parts of HPEG-3000 and 1.5 parts of hydrogen peroxide were added to a reactor containing 200 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After 30 minutes of addition of reaction liquids A and C, reaction liquid B was added dropwise for 90 minutes. During the entire addition process, the temperature of the reaction system was controlled at 30°C. After the addition was completed, the reaction was continued at 30°C for 3 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-4.
[0127] Example 5
[0128] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0129] 4 parts of acrylic acid, 2 parts of methacrylic acid, 0.3 parts of vinyl triethoxysilane, and 10 parts of functional monomer I (GO-2) were added to 200 parts of water and stirred until uniformly dissolved to obtain reaction solution A;
[0130] Add 5 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2.2) into 10 parts of water and stir until dissolved uniformly to obtain reaction solution B;
[0131] 0.5 parts of thioglycolic acid, 0.1 parts of sodium methyl propylene sulfonate and 0.5 parts of sodium bisulfite were added to 20 parts of water and stirred until they were uniformly dissolved to obtain a reaction solution C.
[0132] 2) Polymerization reaction
[0133] 100 parts of TPEG-5000 and 1.5 parts of hydrogen peroxide were added to a reactor containing 200 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 90 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 35°C. After the addition was completed, the reaction was continued at 35°C for 3 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-5.
[0134] Comparative Example 1
[0135] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0136] 5 parts of acrylic acid and 0.2 parts of vinyltriethoxysilane were added to 30 parts of water and stirred until uniformly dissolved to obtain reaction solution A;
[0137] 10 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2) were added to 10 parts of water and stirred until uniformly dissolved to obtain reaction solution B;
[0138] 0.5 parts of mercaptopropionic acid and 0.3 parts of vitamin C were added into 20 parts of water and stirred until they were uniformly dissolved to obtain reaction solution C.
[0139] 2) Polymerization reaction
[0140] 205 parts of HPEG-3000 and 1.3 parts of hydrogen peroxide were added to a reactor containing 197 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 70 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 20°C. After the addition was completed, the reaction was continued at 20°C for 2 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-d1.
[0141] Comparative Example 2
[0142] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0143] Add 5 parts of acrylic acid, 0.2 parts of vinyl triethoxysilane and 5 parts of functional monomer I (GO-1) to 30 parts of water and stir evenly to obtain reaction solution A;
[0144] Add 10 parts of hydroxyethyl acrylate to 10 parts of water and stir until dissolved uniformly to obtain reaction solution B;
[0145] 0.5 parts of mercaptopropionic acid and 0.3 parts of vitamin C were added into 20 parts of water and stirred until they were uniformly dissolved to obtain reaction solution C.
[0146] 2) Polymerization reaction
[0147] 200 parts of HPEG-3000 and 1.3 parts of hydrogen peroxide were added to a reactor containing 197 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 70 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 20°C. After the addition was completed, the reaction was continued at 20°C for 2 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-d2.
[0148] Comparative Example 3
[0149] 1) Providing reaction solution A, reaction solution B and reaction solution C
[0150] 5 parts of acrylic acid, 0.2 parts of vinyl triethoxysilane and monomer GO-d1 were added to 30 parts of water and stirred evenly to obtain reaction solution A;
[0151] 10 parts of functional monomer II (composed of hydroxyethyl acrylate and hydroxypropyl methacrylate in a mass ratio of 1:2) were added to 10 parts of water and stirred until uniformly dissolved to obtain reaction solution B;
[0152] 0.5 parts of mercaptopropionic acid and 0.3 parts of vitamin C were added into 20 parts of water and stirred until they were uniformly dissolved to obtain reaction solution C.
[0153] 2) Polymerization reaction
[0154] 200 parts of HPEG-3000 and 1.3 parts of hydrogen peroxide were added to a reactor containing 197 parts of water and stirred until uniformly dissolved. Then, the temperature control device was turned on and reaction liquid A and reaction liquid C were simultaneously added dropwise for 90 minutes. After reaction liquids A and C were added dropwise for 30 minutes, reaction liquid B was added dropwise for 70 minutes. During the entire dropping process, the temperature of the reaction system was controlled at 20°C. After the addition was completed, the reaction was continued at 20°C for 2 hours to obtain a polycarboxylic acid water reducer, which was recorded as PC-d3.
[0155] Comparative Example 4
[0156] A commercially available slump-retaining water-reducing agent (BASF FS40) was used as a comparative sample and was recorded as PC-d4.
[0157] Test Case
[0158] The test examples are used to illustrate the application performance of the polycarboxylate water reducers PC-1 to PC-5 and PC-d1 to PC-d4 of the above embodiments and comparative examples.
[0159] According to GB / T 8077-2012 "Test method for homogeneity of concrete admixtures", the polycarboxylate water reducer was tested for water reduction rate and air content, where the concrete mix ratio was 175 kg, cement (Chunchi cement P.052.5R): 360 kg, machine-made sand (mud content 5%): 790 kg, stone: 1060 kg, and the amount of water reducer (in solid terms) accounted for 2% of the cement mass.
[0160] In accordance with GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", polycarboxylic acid water reducer was added to the concrete to measure the initial slump, 1h, 2h, 3h slump and 3d, 7d, 28d compressive strength of the concrete. The concrete mix ratio was as follows: water: 175kg, cement (Chunchi cement P.052.5R): 360kg, machine-made sand (mud content 5%): 790kg, stone: 1060kg, and the amount of water reducer was such that the initial slump was controlled between 200 and 220mm.
[0161] The results are shown in Table 1.
[0162] Table 1
[0163]
[0164] Combined with the results shown in Table 1, it can be seen that compared with the commercially available slump-retaining water-reducing agent (Comparative Example 4) and the water-reducing agent prepared by Comparative Examples 1 to 3, Examples 1 to 5 have improved water-reducing performance, reduced air content, and have better slump-retaining effect. Comparing Example 1 with Comparative Examples 1 to 3, it can be seen that under the synergistic effect of functional monomer I and functional monomer II, the prepared water-reducing agent can enable concrete to maintain a higher compressive strength while obtaining a better water-reducing effect and longer slump-retaining property, effectively preventing the occurrence of mid-term slump reverse enlargement.
[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; 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 invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.
Claims
1. A method for preparing a collapse-retaining polycarboxylate water-reducing agent, characterized in that: include: The copolymer monomers including the functional monomer I, the polyether macromonomer, the functional monomer II, the unsaturated carboxylic acid and the unsaturated silane coupling agent I are polymerized in water to form a polycarboxylic acid; wherein: The functional monomer I is prepared by esterification of graphene oxide and diphenyl glycolic acid and then grafting an unsaturated silane coupling agent II; The functional monomer II is hydroxyethyl acrylate and hydroxypropyl methacrylate.
2. The preparation method according to claim 1, characterized in that: The functional monomer I is prepared by a method comprising the following steps: In the presence of an organic solvent and a catalyst, diphenyl glycolic acid and graphene oxide are subjected to an esterification reaction under heating and reflux conditions to form modified graphene oxide; The unsaturated silane coupling agent II is pre-hydrolyzed in a water-containing solvent, and then the modified graphene oxide is added to carry out a grafting reaction to form a functional monomer I; Preferably, the catalyst is at least one of triphenylphosphine, toluenesulfonic acid and thionyl chloride; Preferably, the mass ratio of diphenylhydroxyacetic acid to the graphene oxide is (2-5):1; Preferably, the temperature of the esterification reaction is 90-130°C, and the reaction time is 2-6h; Preferably, the prehydrolysis temperature is 30 to 50° C., and the prehydrolysis time is 0.5 to 3 h; Preferably, the mass ratio of the unsaturated silane coupling agent II to the modified graphene oxide is 1:(0.5-2); Preferably, the aqueous solvent is a mixed solvent of water and ethanol, and the mass concentration of ethanol in the mixed solvent is 40% to 60%; Preferably, the grafting reaction temperature is 60-80° C., and the reaction time is 2-8 hours.
3. The preparation method according to claim 1 or 2, characterized in that: Relative to 100 parts by weight of the polyether macromonomer, the amount of the functional monomer I is 1 to 8 parts by weight, the amount of the functional monomer II is 1 to 10 parts by weight, the amount of the unsaturated carboxylic acid is 1 to 5 parts by weight, and the amount of the unsaturated silane coupling agent I is 0.01 to 0.5 parts by weight; Preferably, the polymerization reaction temperature is 5 to 50° C., and the reaction time is 2 to 10 hours.
4. The preparation method according to any one of claims 1 to 3, characterized in that The polyether macromonomer is one or more of methyl allyl polyoxyethylene ether, isopentenyl polyoxyethylene ether and ethylene glycol monovinyl polyoxyethylene ether.
5. The preparation method according to any one of claims 1 to 4, characterized in that: In the functional monomer II, the mass ratio of hydroxyethyl acrylate to hydroxypropyl methacrylate is 1:(1.2-2.5); Preferably, the unsaturated carboxylic acid is acrylic acid and / or methacrylic acid.
6. The preparation method according to any one of claims 1 to 5, characterized in that: The unsaturated silane coupling agent I and the unsaturated silane coupling agent II are each independently selected from vinyl triethoxy silane and / or vinyl trimethoxy silane; Preferably, the unsaturated silane coupling agent II is vinyltriethoxysilane.
7. The preparation method according to any one of claims 1 to 6, characterized in that: The polymerization reaction is carried out in the presence of an initiator and a chain transfer agent; Preferably, the initiator is a redox initiator; Preferably, the oxidizing agent in the redox initiator is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate; the reducing agent in the redox initiator is selected from at least one of sodium bisulfite, vitamin C and sodium hypophosphite; Preferably, the mass amount of the initiator is 0.1% to 2% of the total mass of the comonomer; Preferably, the chain transfer agent is selected from at least one of mercaptopropionic acid, thioglycolic acid, sodium methacrylic acid and sodium propylene sulfonate; Preferably, the mass amount of the chain transfer agent is 0.05% to 1% of the total mass of the comonomer.
8. The preparation method according to claim 7, characterized in that: The preparation method comprises the following steps: S1: Provide reaction solution A, reaction solution B and reaction solution C respectively The unsaturated carboxylic acid, the unsaturated silane coupling agent I and the functional monomer I are uniformly mixed with water to obtain the reaction solution A; Dissolving the functional monomer II in water to obtain the reaction solution B; Dissolving the chain transfer agent and the reducing agent in water to obtain the reaction solution C; S2: dissolving the polyether macromonomer and the oxidant in water to obtain a base solution; At 5-45°C, the reaction solution A and the reaction solution C are added dropwise to the base solution for a time of t1 and a time of t2. 11 When the reaction liquid B is added dropwise, the addition time of the reaction liquid B is controlled to be t2, wherein; t1 is 50 to 200 minutes, t 11 Satisfies the relationship with t1: t 11 =c×t1, c is 0.1~0.5, t2 is 50 to 200 minutes; Preferably, the amount of water used is such that the solid content of the prepared collapse-retaining polycarboxylate water-reducing agent is 40% to 50%.
9. A collapse-retaining polycarboxylate water-reducing agent prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the collapse-retaining polycarboxylate water-reducing agent according to claim 9 in building materials.