Slump-loss-free super-slow-release type water reducing agent mother liquor and preparation process thereof

Abstract

The invention belongs to the technical field of preparation of water reducing agents, and particularly relates to a slump-loss-free super-slow-release type water reducing agent mother solution and a preparation process thereof. The method comprises the following steps: copolymerizing a phosphoric acid functional monomer, an amide functional monomer, a polyether monomer and unsaturated carboxylic acid to obtain a mother solution of the super-slow-release water reducing agent; functional groups such as acylamino and ester groups introduced on a molecular chain of the water reducer can be slowly hydrolyzed into anion anchoring groups such as carboxyl in an alkaline environment, so that secondary adsorption of the water reducer and cement particles is promoted, and the water reducer has relatively long slump retaining performance and relatively high compressive strength.

Description

Technical Field

[0001] The present application belongs to the technical field of water reducing agent preparation, and in particular relates to a non-collapse ultra-slow-release water reducing agent mother solution and a preparation process thereof. Background Art

[0002] Concrete is a composite material composed of a cementitious medium and aggregate particles and fragments. It is favored by engineers because of its low price, easy availability, good water resistance, plasticity and fluidity, and has become one of the most important materials in the civil engineering industry. With the advancement of science and the development of the times, the utilization rate of concrete is constantly increasing, and the performance of concrete is also being required to be higher. As we all know, excellent performance is inseparable from high-quality materials. At present, high-quality sand and gravel aggregates are continuously mined and utilized, resulting in the scarcity of high-quality materials and difficulty in obtaining materials. In order to improve the performance of concrete, it is necessary to conduct research on concrete admixtures to promote the development of the concrete industry.

[0003] As the third generation of high-performance water reducers, polycarboxylate water reducers have become the most widely used type of water reducers in concrete due to their advantages of low preparation cost, high water reduction rate, green environmental protection and multifunctionality. Polycarboxylate water reducers are comb-shaped copolymers with hydrophilic anchoring groups such as carboxyl groups in the main chain and grafted with polyoxyethylene side chains. Its structure mainly consists of two parts. The main chain mainly plays an adsorption role and is adsorbed to the surface of cement particles through the charge action of negative ion groups such as carboxyl groups and sulfonic acid groups and the surface of cement particles. The side chain is a long hydrophilic chain that hinders the adhesion between particles through steric hindrance, and this effect does not weaken with the extension of time. In recent years, the high performance and green requirements of concrete have promoted the functionalization and green development of water reducers. Therefore, the research on functional polycarboxylate water reducers will play a vital role in the development of the concrete industry.

[0004] The Chinese patent with announcement number CN109796561B discloses an aromatic ring polycarboxylic acid water-reducing agent mother liquor and its preparation method and application. The mother liquor is prepared by a quaternary copolymerization reaction of an aromatic conjugated unsaturated carboxylic acid, an unsaturated functional monomer, an unsaturated fatty carboxylic acid and an isopentenyl polyoxyethylene ether macromonomer. The selected aromatic conjugated unsaturated carboxylic acid itself has antibacterial and anticorrosive properties, so that the copolymer side chain structure has anti-mildew and antibacterial functional groups, which can play an anti-mildew and antibacterial role during the placement of the water-reducing agent. At the same time, the aromatic group also has a large steric hindrance, which effectively slows down the initial release of the carboxyl group of the water-reducing agent and the adsorption by cement particles, thereby playing a slow-release role and enhancing the slump retention ability of the concrete. The Chinese patent with the announcement number CN118063127B discloses a polycarboxylate water-reducing agent and a preparation method and application thereof. The polycarboxylate water-reducing agent mother liquor, hydroxypropyl methylcellulose, polysilicate aluminum ferric sulfate, organic acid anhydride, phosphorus-doped polyaniline / graphene composite material, defoamer and water are used as raw materials for reaction. The polycarboxylate water-reducing agent mother liquor is pretreated with polysilicate aluminum ferric sulfate and hydroxypropyl methylcellulose. The electrostatic repulsion between the functional groups of polysilicate aluminum ferric sulfate and hydroxypropyl methylcellulose can be used to assist the dispersion of particles in the polycarboxylate water-reducing agent mother liquor, and avoid the agglomeration of particles in the water-reducing agent to affect the fluidity of the concrete slurry. By modifying the surface of graphene with polyaniline, the dispersibility and chemical stability of graphene are effectively improved, so that the graphene is evenly dispersed in the polycarboxylate water-reducing agent mother liquor, and the particles in the polycarboxylate water-reducing agent mother liquor can be better isolated and dispersed, and the agglomeration between the particles is further prevented. However, the above modifications are all made by directly compounding the raw materials. Although they can alleviate the loss of concrete slump to a certain extent, facing the increasingly high performance requirements for concrete, higher requirements are placed on the performance of water reducers. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a super-slow-release water-reducing agent mother liquor without collapse loss and a preparation process thereof. The super-slow-release water-reducing agent mother liquor is obtained by copolymerizing a phosphoric acid functional monomer, an amide functional monomer, a polyether monomer and an unsaturated carboxylic acid, which can improve the collapse-preserving performance of the water-reducing agent mother liquor and has higher compressive strength.

[0006] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0007] A process for preparing a non-slump-loss ultra-slow-release water-reducing agent mother solution comprises the following steps:

[0008] S100, using raw materials including polyphosphoric acid and epoxy ester compounds to obtain phosphoric acid functional monomers through epoxy ring-opening reaction;

[0009] S200, using raw materials including aliphatic compounds and unsaturated carboxylic acids to obtain amide functional monomers through acylation reaction;

[0010] The super slow-release water reducing agent mother solution is obtained by copolymerizing S300, phosphoric acid functional monomers, amide functional monomers, polyether monomers and unsaturated carboxylic acids.

[0011] As one of the most important chemical admixtures, water reducer can be added to cementitious materials and adsorbed to the surface of cementitious material particles, destroying the flocculation structure between particles, thus reducing the amount of water used. Polycarboxylic acid water reducer has the characteristics of low output, high water reduction rate, and good slump retention. Adding it to cement concrete can reduce the amount of mixing water, improve the workability and workability of concrete, and make the concrete have excellent mechanical properties and durability. However, with the increase in applications, the compatibility problem between it and concrete is gradually exposed. Therefore, in the present invention, a polycarboxylic acid water reducer modified with phosphorus-containing groups and amide groups is obtained by copolymerizing phosphoric acid functional monomers, amide functional monomers and unsaturated carboxylic acids, so that it has better dispersibility and has a stronger slow setting effect on cement.

[0012] Furthermore, S100 specifically includes: mixing phytic acid and dimethyl sulfoxide and reacting them at 45-60°C for 25-45 minutes, adding a mixed solution of glycidyl methacrylate and dimethyl sulfoxide thereto, and reacting at a constant temperature for 45-55 hours after the addition is completed to obtain a phosphoric acid functional monomer; wherein the preparation process of the mixed solution is: adding glycidyl methacrylate to dimethyl sulfoxide and stirring evenly to obtain; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1-1.5:10; the mass ratio of phytic acid, dimethyl sulfoxide and the mixed solution is 4.5-6.5:11-12:40-60; wherein the mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added in a dropwise manner.

[0013] In this step, phytic acid and glycidyl methacrylate are used as raw materials, and polyphosphoric acid is chemically bonded to glycidyl methacrylate through epoxy ring opening to prepare phosphoric acid functional monomers. As an anionic group, the phosphorus-containing group is introduced into the molecular structure of polycarboxylate water-reducing agent as an anchoring group to enhance its binding ability with calcium ions, so that the prepared polycarboxylate water-reducing agent molecules are more easily adsorbed to the surface of cement particles, further improving its dispersibility. At the same time, the six-membered ring contained in phytic acid has a larger steric hindrance than the straight-chain molecular structure, which can effectively improve the anti-clay effect of polycarboxylate water-reducing agent and reduce the adsorption amount on bentonite. Polycarboxylate water-reducing agent is more sensitive to the clay content in sandstone aggregates. On the one hand, clay will compete for the adsorption of polycarboxylate water-reducing agent, and on the other hand, the polyether side chain of polycarboxylate water-reducing agent can be intercalated into the interlayer structure of clay, resulting in ineffective adsorption of polycarboxylate water-reducing agent, reducing the water reduction and slump retention performance of polycarboxylate water-reducing agent. Since the adsorption capacity of the phosphate group is stronger than that of the carboxylic acid group, it can be adsorbed onto cement particles faster. In addition, the charge density of the phosphate group is higher than that of the carboxylic acid group. As the water reducer is adsorbed on the surface of cement particles, the same charges on the surface of the material will repel each other, resulting in a decrease in the amount of adsorption on the cement particles. In addition, calcium phosphate is insoluble in water, and covering the surface of cement particles can hinder the further adsorption of the water reducer on the surface of cement particles, thereby improving the clay tolerance of polycarboxylic acid water reducers containing phosphate groups.

[0014] Furthermore, S200 specifically includes: under an inert atmosphere, uniformly mixing 6-aminocaproic acid ethyl ester, acrylic acid and an inhibitor, raising the temperature to 65-85°C and reacting for 2-4 hours to obtain an amide functional monomer; wherein the inert atmosphere is a nitrogen atmosphere; the inhibitor is hydroquinone; and the mass ratio of 6-aminocaproic acid ethyl ester, acrylic acid and the inhibitor is 1:1.8-2.8:0.03-0.06.

[0015] In this step, 6-aminocaproic acid ethyl ester and acrylic acid are used as raw materials, and amide functional monomers are obtained through acylation reaction. Ordinary Portland cement is mainly composed of four chemical components: calcium oxide, silicon dioxide, ferric oxide, and aluminum oxide. Cement will produce alkaline substances during the hydration process, making the cement paste alkaline. Amide groups and ester groups are introduced into the molecular chain of polycarboxylic acid water reducer through amidation reaction. The functional groups such as ester groups and amide groups carried by it will slowly hydrolyze into anionic anchoring groups such as carboxyl groups in an alkaline environment, thereby promoting the water reducer molecules to adsorb to cement particles for the second time, so that it has a longer collapse retention performance.

[0016] Further, S300 specifically includes: adding methyl allyl polyoxyethylene ether and deionized water to a reactor, stirring at 25-30°C until completely dissolved, then adding phosphoric acid functional monomers and amide functional monomers thereto, stopping heating after mixing evenly, then adding hydrogen peroxide and acrylic acid thereto, stirring evenly, adding vitamin C aqueous solution and 3-mercaptopropionic acid thereto, reacting at a constant temperature for 1.5-3h, adjusting the pH to 5-6 after the reaction, cooling to room temperature, and obtaining the ultra-slow-release water-reducing agent mother liquor; wherein the preparation process of the vitamin C aqueous solution is: dissolving vitamin C in deionized water and stirring until dissolved; the amount of vitamin C in deionized water is 0.006-0.01g / mL.

[0017] The carboxyl groups contained in polycarboxylic acid water reducers can act as collapse-preserving groups. During the mixing process with cement particles, the anionic groups in the polycarboxylic acid molecules can combine with the cationic ions of cement particles, so that the polycarboxylic acid water reducer is anchored on the surface of cement particles, resulting in a decrease in the number of cations, and the rate of anion-cation combination slows down, which inhibits the hydration of cement to a certain extent and plays a collapse-preserving role. In the preparation process of polycarboxylic acid water reducers, the introduction of phosphoric acid functional monomers can form complexes with inorganic substances to affect the hydration reaction. Its strong complexation and adsorption capacity show strong dispersion performance; in addition, the introduction of amide functional monomers allows the polycarboxylic acid water reducer molecules to slowly hydrolyze into anchoring groups such as carboxyl groups in an alkaline environment, prompting the water reducer molecules to perform secondary adsorption on cement particles, so that it has better sustained-release performance. In addition, after the modification of phosphoric acid functional monomers and amide functional monomers, the synergistic effect between nitrogen and phosphorus contained in the polycarboxylic acid molecular chain promotes the self-detachment of phosphoric acid protons, assists the formation of a continuous hydrogen bond network between phosphoric acid molecules, produces a large steric hindrance, and promotes the dispersion between cement particles. In addition, the long-chain molecules of methyl allyl polyoxyethylene ether can form a molecular adsorption layer in the water phase and form an interface layer between water and the solid phase, effectively maintaining the relative stability between cement particles and maintaining its flow properties; at the same time, it can also form hydrogen bonds with water, reducing the adhesion between water and the surface of cement particles and playing a water-reducing role; hydrogen bonds can be formed between its molecular chains, so that its molecules adhere to each other to form a dense molecular network structure, which plays a role in enhancing the compression and crack resistance of cement.

[0018] The present invention also provides a super-slow-release water-reducing agent mother solution without collapse loss, and the super-slow-release water-reducing agent mother solution is obtained by using the preparation process of the super-slow-release water-reducing agent mother solution without collapse loss as described in any of the above technical solutions.

[0019] The present invention has the following beneficial effects:

[0020] Phosphoric acid functional monomers are prepared by chemically bonding polyphosphoric acid to glycidyl methacrylate using phytic acid and glycidyl methacrylate as raw materials through epoxy ring opening; introducing phosphorus-containing groups into the molecular structure of polycarboxylic acid water-reducing agent as anchoring groups can enhance its binding ability with calcium ions, making the prepared polycarboxylic acid water-reducing agent molecules more easily adsorbed to the surface of cement particles, further improving its dispersion performance, and at the same time, the six-membered ring contained in phytic acid has a larger steric hindrance than the straight-chain molecular structure, which can effectively improve the anti-clay effect of polycarboxylic acid water-reducing agent and reduce the adsorption amount on bentonite. Amide functional monomers are obtained by acylation reaction using 6-aminocaproic acid ethyl ester and acrylic acid as raw materials. The functional groups such as ester and amide groups carried by it will slowly hydrolyze into anionic anchoring groups such as carboxyl groups in an alkaline environment, thereby promoting the second adsorption of water-reducing agent molecules and cement particles, so that it has a longer collapse retention performance. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] Phytic acid (Shanghai test, biochemical reagent BR), dimethyl sulfoxide (analytical grade), glycidyl methacrylate (Alfa-L11133, 97%), 6-aminohexanoic acid ethyl ester (Alfa-H50296, 98%), 3-mercaptopropionic acid (Acros-C12553) used in the present invention are purchased from Sinopharm Chemical Reagent Co., Ltd., acrylic acid (industrial grade, purity 99.24%), methyl allyl polyoxyethylene ether (Aoke Chemical Co., Ltd., molecular weight 2400), hydrogen peroxide (industrial grade, main content of 27.56%), vitamin C (industrial grade, main content of 99.89%), all reagents are commonly available on the market.

[0023] Embodiment 1

[0024] A process for preparing a non-slump-loss ultra-slow-release water-reducing agent mother solution comprises the following steps:

[0025] S100, using raw materials including polyphosphate and epoxy ester compounds, obtaining phosphoric acid functional monomers through epoxy ring-opening reaction; specifically, phytic acid and dimethyl sulfoxide are mixed and reacted at 55°C for 35 minutes, and then a mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added thereto, and after the addition is completed, the mixture is reacted at a constant temperature of 55°C for 52 hours to obtain a phosphoric acid functional monomer; wherein the preparation process of the mixed solution is: glycidyl methacrylate is added to dimethyl sulfoxide and stirred evenly to obtain; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1.2:10; the mass ratio of phytic acid, dimethyl sulfoxide and the mixed solution is 5.5:11.2:48; wherein the mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added in a dropwise manner;

[0026] S200, using raw materials including aliphatic compounds and unsaturated carboxylic acids to obtain amide functional monomers through acylation reaction; specifically, in a nitrogen atmosphere, 6-aminocaproic acid ethyl ester, acrylic acid and inhibitor hydroquinone are uniformly mixed, and the temperature is increased to 75° C. to react for 3 hours to obtain amide functional monomers; wherein the mass ratio of 6-aminocaproic acid ethyl ester, acrylic acid and inhibitor is 1:2.2:0.04;

[0027] S300, phosphoric acid functional monomer, amide functional monomer, polyether monomer and unsaturated carboxylic acid are copolymerized to obtain the super sustained-release water reducer mother liquor; specifically: 120 parts by weight of methyl allyl polyoxyethylene ether and 110 parts by weight of deionized water are added to the reactor and stirred at 30°C until completely dissolved, then 52 parts by weight of phosphoric acid functional monomer and 45 parts by weight of amide functional monomer are added thereto, and heating is stopped after mixing evenly, and then 3 parts by weight of hydrogen peroxide and 20 parts by weight of acrylic acid are added thereto, and after stirring evenly, 16 parts by weight of vitamin C aqueous solution and 3 parts by weight of 3-mercaptopropionic acid are added thereto, and after the addition is completed, the reaction is carried out at a constant temperature of 30°C for 2h, and after the reaction is completed, the pH is adjusted to 5-6 with 30% sodium hydroxide solution, and the solution is cooled to room temperature to obtain the super sustained-release water reducer mother liquor; wherein the preparation process of the vitamin C aqueous solution is: dissolving vitamin C in deionized water and stirring until dissolved, that is, obtaining; the amount of vitamin C in deionized water is 0.008g / mL.

[0028] Embodiment 2

[0029] This embodiment is different from the first embodiment in the following aspects:

[0030] In step S100, phytic acid and dimethyl sulfoxide are mixed and reacted at 45°C for 25 minutes, and then a mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added thereto. After the addition is completed, the mixture is kept at 45°C for 45 hours; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1:10; the mass ratio of phytic acid, dimethyl sulfoxide and the mixed solution is 4.5:11:40.

[0031] In step S200, 6-aminocaproic acid ethyl ester, acrylic acid and polymerization inhibitor hydroquinone are mixed evenly, and the temperature is raised to 65° C. to react for 2 hours; the mass ratio of 6-aminocaproic acid ethyl ester, acrylic acid and polymerization inhibitor is 1:1.8:0.03.

[0032] In step S300, 90 parts by weight of methyl allyl polyoxyethylene ether and 85 parts by weight of deionized water are added to a reactor and stirred at 25° C. until completely dissolved, and then 28 parts by weight of phosphoric acid functional monomers and 22 parts by weight of amide functional monomers are added thereto, and the heating is stopped after mixing evenly, and then 0.8 parts by weight of hydrogen peroxide and 12 parts by weight of acrylic acid are added thereto, and after stirring evenly, 14 parts by weight of vitamin C aqueous solution and 1 part by weight of 3-mercaptopropionic acid are added thereto. After the addition is completed, the reaction is carried out at a constant temperature of 25° C. for 1.5 hours. After the reaction is completed, the pH is adjusted to 5-6 with 30% sodium hydroxide solution, and the reaction is cooled to room temperature to obtain an ultra-slow-release water reducer mother liquor; the amount of vitamin C in deionized water is 0.006 g / mL.

[0033] Embodiment 3

[0034] This embodiment is different from the first embodiment in the following aspects:

[0035] In step S100, phytic acid and dimethyl sulfoxide are mixed and reacted at 60°C for 45 minutes, and then a mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added thereto. After the addition is completed, the mixture is kept at 60°C for 55 hours; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1.5:10; the mass ratio of phytic acid, dimethyl sulfoxide and the mixed solution is 6.5:12:60.

[0036] In step S200, 6-aminocaproic acid ethyl ester, acrylic acid and polymerization inhibitor hydroquinone are mixed evenly, and the temperature is raised to 85° C. to react for 4 hours; the mass ratio of 6-aminocaproic acid ethyl ester, acrylic acid and polymerization inhibitor is 1:2.8:0.06.

[0037] In step S300, 150 parts by weight of methyl allyl polyoxyethylene ether and 150 parts by weight of deionized water are added to a reactor and stirred at 30° C. until completely dissolved, and then 80 parts by weight of phosphoric acid functional monomers and 72 parts by weight of amide functional monomers are added thereto, and heating is stopped after mixing evenly, and then 5 parts by weight of hydrogen peroxide and 28 parts by weight of acrylic acid are added thereto, and after stirring evenly, 20 parts by weight of vitamin C aqueous solution and 6 parts by weight of 3-mercaptopropionic acid are added thereto. After the addition is completed, the reaction is carried out at a constant temperature of 30° C. for 3 hours. After the reaction is completed, the pH is adjusted to 5-6 with 30% sodium hydroxide solution, and the mixture is cooled to room temperature to obtain an ultra-slow-release water-reducing agent mother liquor; the amount of vitamin C in deionized water is 0.01 g / mL.

[0038] Comparative Example 1

[0039] Compared with Example 1, this comparative example adopts aminotrimethylene phosphoric acid as polyphosphoric acid to prepare phosphoric acid functional monomer, and the rest is referred to Example 1.

[0040] S100, aminotrimethylene phosphoric acid and dimethyl sulfoxide are mixed and reacted at 55°C for 35 minutes, and then a mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added thereto, and after the addition is completed, the mixture is reacted at a constant temperature of 55°C for 52 hours to obtain a phosphoric acid functional monomer; wherein the preparation process of the mixed solution is: glycidyl methacrylate is added to dimethyl sulfoxide and stirred evenly to obtain; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1.2:10; the mass ratio of aminotrimethylene phosphoric acid, dimethyl sulfoxide and the mixed solution is 2.5:11.2:48; wherein the mixed solution of glycidyl methacrylate and dimethyl sulfoxide is added in a dropwise manner.

[0041] The remaining steps refer to Example 1.

[0042] Comparative Example 2

[0043] Compared with Example 1, this comparative example adopts n-hexylamine as the aliphatic compound to prepare the amide functional monomer, and the rest is referred to Example 1.

[0044] S200. Under a nitrogen atmosphere, n-hexylamine, acrylic acid and inhibitor hydroquinone are mixed evenly, and the temperature is raised to 75° C. to react for 3 hours to obtain an amide functional monomer; wherein the mass ratio of n-hexylamine, acrylic acid and inhibitor is 0.67:2.2:0.04.

[0045] The remaining steps refer to Example 1.

[0046] Comparative Example 3

[0047] Compared with Example 1, in this comparative example, no phosphoric acid functional monomer is added during the preparation of the water reducing agent mother solution, and the rest is the same as Example 1.

[0048] The preparation process of the water reducer mother liquor is as follows: 120 parts by weight of methyl allyl polyoxyethylene ether and 110 parts by weight of deionized water are added to a reactor and stirred at 30°C until completely dissolved, then 45 parts by weight of amide functional monomers are added thereto, and heating is stopped after mixing evenly, and then 2.2 parts by weight of hydrogen peroxide and 12 parts by weight of acrylic acid are added thereto, and after stirring evenly, 12 parts by weight of vitamin C aqueous solution and 2.2 parts by weight of 3-mercaptopropionic acid are added thereto, and after the addition is completed, the reaction is carried out at a constant temperature of 30°C for 2 hours, and after the reaction is completed, the pH is adjusted to 5-6 with a 30% sodium hydroxide solution, and the solution is cooled to room temperature to obtain the water reducer mother liquor; wherein the preparation process of the vitamin C aqueous solution is as follows: vitamin C is dissolved in deionized water and stirred until dissolved, and the amount of vitamin C in the deionized water is 0.008 g / mL.

[0049] The amide functional monomers are prepared by referring to the amide functional monomers in Example 1.

[0050] Comparative Example 4

[0051] Compared with Example 1, in this comparative example, no amide functional monomer is added during the preparation of the water reducing agent mother solution, and the rest is the same as Example 1.

[0052] The preparation process of the water reducer mother liquor is as follows: 120 parts by weight of methyl allyl polyoxyethylene ether and 110 parts by weight of deionized water are added to a reactor and stirred at 30°C until completely dissolved, then 52 parts by weight of phosphoric acid functional monomers are added thereto, and heating is stopped after mixing evenly, and then 2.5 parts by weight of hydrogen peroxide and 15 parts by weight of acrylic acid are added thereto, and after stirring evenly, 14 parts by weight of vitamin C aqueous solution and 2.5 parts by weight of 3-mercaptopropionic acid are added thereto, and after the addition is completed, the reaction is carried out at a constant temperature of 30°C for 2 hours, and after the reaction is completed, the pH is adjusted to 5-6 with a 30% sodium hydroxide solution, and the solution is cooled to room temperature to obtain the water reducer mother liquor; wherein the preparation process of the vitamin C aqueous solution is as follows: vitamin C is dissolved in deionized water and stirred until dissolved, and the amount of vitamin C in the deionized water is 0.008 g / mL.

[0053] Phosphoric acid functional monomers are prepared by referring to Example 1.

[0054] Comparative Example 5

[0055] Compared with Example 1, in this comparative example, no phosphoric acid functional monomer and amide functional monomer are added during the preparation of the water reducing agent mother solution, and the rest is the same as Example 1.

[0056] The preparation process of the water reducer mother liquor is as follows: 120 parts by weight of methyl allyl polyoxyethylene ether and 110 parts by weight of deionized water are added to a reactor, stirred at 30°C until completely dissolved, and then heating is stopped, and then 1.2 parts by weight of hydrogen peroxide and 40 parts by weight of acrylic acid are added thereto, and after stirring evenly, 8 parts by weight of a vitamin C aqueous solution and 1.2 parts by weight of 3-mercaptopropionic acid are added thereto, and after the addition is completed, the reaction is carried out at a constant temperature of 30°C for 2 hours, and after the reaction is completed, the pH is adjusted to 5-6 with a 30% sodium hydroxide solution, and the solution is cooled to room temperature to obtain the water reducer mother liquor; wherein the preparation process of the vitamin C aqueous solution is as follows: vitamin C is dissolved in deionized water and stirred until dissolved, and the amount of vitamin C in the deionized water is 0.008 g / mL.

[0057] Related tests:

[0058] The water reducing agent mother solutions prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were applied to concrete at a dosage of 0.16% of the total weight of the cementitious material, and the performance of the concrete was tested. The specific method was based on the test in accordance with GB8076-2008 "Concrete Admixtures", where the slump test results are shown in Table 1, and the compressive strength results are shown in Table 2.

[0059] Table 1 Slump test results

[0060]

[0061] Table 2 Compressive strength test results

[0062]

[0063] It can be seen from the test results in Table 1 and Table 2 that the relevant performance of the water-reducing agent mother liquor prepared in Examples 1 to 3 is better than that in Comparative Examples 1 to 5; by comparing Example 1 with Comparative Example 1 (replacing phytic acid with aminotrimethylene phosphoric acid) and Comparative Example 3 (no addition of phosphoric acid functional monomer), it can be seen that after the introduction of the phosphate group into the water-reducing agent molecular chain, its slump and compressive strength are improved to a certain extent. This is because the adsorption capacity of the phosphate group is stronger than that of the carboxylic acid group, which can enhance the binding ability with calcium ions as an anchoring group, so that the prepared water-reducing agent molecules are more easily adsorbed to the surface of cement particles; at the same time, since the six-membered ring contained in the phytic acid has a large steric hindrance, its dispersibility can be further improved. By comparing Example 1 with Comparative Example 2 (replacing 6-aminocaproic acid ethyl ester with n-hexylamine) and Comparative Example 4 (not adding amide functional monomers), it can be seen that the functional groups such as amide groups and ester groups introduced on the water reducer molecular chain will slowly hydrolyze into anionic anchoring groups such as carboxyl groups under alkaline conditions, thereby promoting the secondary adsorption of the water reducer and cement particles, so that it has a longer slump retention performance. By comparing Example 1 with Comparative Example 3 (not adding phosphoric acid functional monomers), Comparative Example 4 (not adding amide functional monomers) and Comparative Example 5 (not adding phosphoric acid functional monomers and amide functional monomers), it can be seen that after modification by phosphoric acid functional monomers and amide functional monomers, there is a synergistic effect between the nitrogen and phosphorus contained in the water reducer molecular chain, which assists the phosphoric acid molecules to form a continuous hydrogen bond network, produces steric hindrance, and further promotes the dispersion between cement particles.

[0064] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0065] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a non-collapse super-slow-release water-reducing agent mother solution, characterized in that: The steps include: S100, using raw materials including polyphosphoric acid and epoxy ester compounds to obtain phosphoric acid functional monomers through epoxy ring-opening reaction; S200, using raw materials including aliphatic compounds and unsaturated carboxylic acids to obtain amide functional monomers through acylation reaction; The super slow-release water reducing agent mother solution is obtained by copolymerizing S300, phosphoric acid functional monomers, amide functional monomers, polyether monomers and unsaturated carboxylic acids.

2. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 1, characterized in that: S100 specifically comprises: mixing phytic acid and dimethyl sulfoxide and reacting them at 45-60° C. for 25-45 minutes, then adding a mixed solution of glycidyl methacrylate and dimethyl sulfoxide, and reacting them at a constant temperature for 45-55 hours after the addition is completed, to obtain a phosphoric acid functional monomer.

3. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 2, characterized in that: The preparation process of the mixed solution is: adding glycidyl methacrylate to dimethyl sulfoxide and stirring evenly to obtain the mixed solution; the mass ratio of glycidyl methacrylate to dimethyl sulfoxide is 1-2:

10.

4. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 1, characterized in that: S200 specifically includes: in an inert atmosphere, uniformly mixing 6-aminocaproic acid ethyl ester, acrylic acid and a polymerization inhibitor, raising the temperature to 65-85° C. and reacting for 2-4 hours to obtain an amide functional monomer.

5. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 4, characterized in that: The mass ratio of 6-aminocaproic acid ethyl ester, acrylic acid and polymerization inhibitor is 1:1.8-2.8:0.03-0.

06.

6. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 1, characterized in that: S300 specifically includes: adding methyl allyl polyoxyethylene ether and deionized water into a reactor, stirring at 25-30° C. until completely dissolved, then adding phosphoric acid functional monomer and amide functional monomer thereto, stopping heating after mixing evenly, then adding hydrogen peroxide and acrylic acid thereto, stirring evenly, adding vitamin C aqueous solution and 3-mercaptopropionic acid thereto, reacting at a constant temperature for 1.5-3h after the reaction is completed, adjusting the pH to 5-6 after the reaction is completed, and cooling to room temperature to obtain the ultra-slow-release water-reducing agent mother liquor.

7. The process for preparing the non-collapse super-slow-release water-reducing agent mother solution according to claim 6, characterized in that: In step S300, the preparation process of the vitamin C aqueous solution is: dissolving vitamin C in deionized water and stirring until dissolved; the amount of vitamin C in the deionized water is 0.006-0.01 g / mL.

8. A super slow-release water reducing agent mother solution without collapse loss, characterized in that: The super slow-release water-reducing agent mother solution is obtained by using the preparation process of the super slow-release water-reducing agent mother solution without collapse loss as described in any one of claims 1 to 7.

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