Slump retaining agent as well as preparation method and application thereof

Abstract

The invention provides a slump retaining agent as well as a preparation method and application thereof, the slump retaining agent is formed by polymerizing a double-terminated esterification functional monomer, unsaturated carboxylic acid, unsaturated ester and unsaturated amide, and the double-terminated esterification functional monomer is obtained by performing esterification reaction on polyethylene glycol, methacrylic acid and amino acid. The slump retaining agent has excellent mud resistance and slump retaining property. According to the invention, introduction of polyether long side chains easy to generate physical adsorption and chemical intercalation is avoided; meanwhile, physical adsorption is reduced by introducing cation and anion groups; by adding amino acid and introducing a rigid end-capped structure benzene ring, chemical intercalation of the slump retaining agent in layered clay mineral is avoided, so that the tolerance of the slump retaining agent to clay is improved; ester groups formed by the esterification reaction can be hydrolyzed to form polyhydroxy and carboxyl substances, the polyhydroxy and carboxyl substances interact with the surfaces of cement particles, the dispersion effect of cement is enhanced, and concrete prepared from the cement has excellent mud resistance and slump loss resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete building materials, and particularly relates to a collapse retaining agent and a preparation method and application thereof. Background Art

[0002] Slump-retaining agent is a chemical additive used in concrete. Its main function is to delay the slump loss of concrete, thereby maintaining the fluidity and workability of concrete. Compared with traditional slump-retaining agents (such as polynaphthalene sulfonate, polymelamine sulfonate and acetone-formaldehyde-sulfonate polycondensate), polycarboxylic acid polymer (PCE) can achieve significant water reduction effect at a lower dosage, thereby improving the fluidity and slump-retaining property of concrete. PCE has become an important part of modern concrete technology and has promoted the development and application of high-performance concrete.

[0003] However, the clay in concrete aggregate has a high specific surface area and layered structure, which is prone to excessive adsorption and chemical intercalation with PCE, reducing the effective concentration of PCE on the surface of cement particles, reducing the fluidity and slump retention of concrete, accelerating the slump loss, and increasing the difficulty of construction operations.

[0004] Therefore, how to provide a collapse-preventing agent with excellent mud resistance and collapse-preventing properties is a technical problem to be solved urgently in this field. Summary of the invention

[0005] The invention provides a collapse preventing agent, which does not introduce a polyether long side chain that is easy to generate physical adsorption and chemical intercalation with clay and has excellent mud resistance and collapse preventing properties.

[0006] The invention also provides a method for preparing a collapse-preventing agent. The collapse-preventing agent prepared by the preparation method has excellent mud resistance and collapse-preventing properties.

[0007] The present invention also provides concrete, which adopts the slump-preventing agent and has excellent fluidity and slump-preventing properties.

[0008] In a first aspect, the present invention provides a collapse-preventing agent, which is polymerized from a double-terminated esterification functional monomer, an unsaturated carboxylic acid, an unsaturated ester and an unsaturated amide;

[0009] The double-terminated esterification functional monomer is obtained by esterification reaction of polyethylene glycol, methacrylic acid and amino acid.

[0010] The collapse-preserving agent as described above, wherein the amino acid comprises phenylalanine and / or tyrosine.

[0011] The collapse retaining agent as described above, wherein the mass ratio of the double-terminated esterification functional monomer, the unsaturated ester, the unsaturated carboxylic acid, and the unsaturated amide is (30-45): (3.5-6.5): (1-2): 1.

[0012] The collapse-preventing agent as described above, wherein the mass ratio of the polyethylene glycol, the amino acid and the methacrylic acid is (9-18):(1.8-2.5):1.

[0013] The collapse-preventing agent as described above, wherein the double-terminated esterification functional monomer comprises a compound as shown in Formula 1 below:

[0014] Formula 1;

[0015] In formula 1, n=16~35, and R is a hydrogen atom or a hydroxyl group.

[0016] The collapse-preserving agent as described above, wherein the unsaturated carboxylic acid comprises a compound shown in Formula 2:

[0017] Formula 2;

[0018] In Formula 2, R1, R2, and R3 are each independently a hydrogen atom, a C1-C5 alkyl group, or a carboxyl group having 1 to 5 carbon atoms.

[0019] The collapse-preserving agent as described above, wherein the unsaturated ester comprises a compound shown in Formula 3 below:

[0020] Formula 3;

[0021] In Formula 3, R4, R5, and R6 are each independently a hydrogen atom or a C1-C5 alkyl group, and R7 is independently a C1-C5 alkyl group.

[0022] The collapse-preserving agent as described above, wherein the unsaturated amide comprises a compound shown in Formula 4 below:

[0023] Formula 4;

[0024] In formula 4, R8, R9, R 10 , R 11 , R 12 Each is independently a hydrogen atom or a C1~C5 alkyl group.

[0025] The collapse-preventing agent as described above, wherein the collapse-preventing agent comprises a compound shown in the following formula 5:

[0026] Formula 5;

[0027] In formula 5, n=16-35, m1=10-50, m2=5-40, m3=18-85, m4=6-30, R is a hydrogen atom or a hydroxyl group, R1, R2, and R3 are each independently a hydrogen atom, a C1-C5 alkyl group, or a carboxyl group having 1 to 5 carbon atoms; R4, R5, R6, R8, R9, and R10 , R 11 , R 12 Each is independently a hydrogen atom or a C1~C5 alkyl group; R7 is independently a C1~C5 alkyl group.

[0028] The collapse-preventing agent as described above, wherein the weight average molecular weight of the collapse-preventing agent is 51000-61000.

[0029] The present invention provides in a second aspect a method for preparing the collapse-preventing agent according to the first aspect, comprising the following steps:

[0030] 1) Mix 360-400 parts of polyethylene glycol, 20-43 parts of methacrylic acid, 40-90 parts of amino acid, 11-25 parts of catalyst and 9-20 parts of inhibitor by weight, and carry out esterification reaction under an inert atmosphere to obtain a double-terminated esterification functional monomer;

[0031] 2) 3.2-7.8 parts of initiator, 1.6-8 parts of chain transfer agent, 0.7-1.9 parts of reducing agent, 14-30 parts of unsaturated carboxylic acid, 57-80 parts of unsaturated ester and 9-20 parts of unsaturated amide are added dropwise to the double-terminated esterified functional monomer, and a polymerization reaction is carried out under an inert atmosphere to obtain the collapse retaining agent.

[0032] In the preparation method as described above, the initiator comprises at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate or azobisisobutyronitrile.

[0033] In the preparation method as described above, the reducing agent includes at least one of vitamin C, ferrous sulfate, cuprous sulfate, oxalic acid, sodium bisulfite or sodium sulfite.

[0034] The preparation method as described above, wherein the step 2) further comprises adding water to the double-capped esterification functional monomer.

[0035] In the preparation method as described above, in step 1), in the esterification reaction, the reaction temperature is 105-120° C. and the reaction time is 7-11 h.

[0036] The preparation method as described above, wherein in step 2), the dripping time is 1 to 3.5 hours.

[0037] In the preparation method as described above, in step 2), in the polymerization reaction, the reaction temperature is 55-60° C. and the reaction time is 2-6 hours.

[0038] The present invention provides a concrete in a third aspect, wherein the concrete comprises the collapse retaining agent described in the first aspect.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The collapse retaining agent of the present invention is prepared by polymerization reaction of double-terminated esterification functional monomer, unsaturated carboxylic acid, unsaturated ester and unsaturated amide, wherein the double-terminated esterification functional monomer is obtained by esterification reaction of polyethylene glycol, methacrylic acid and amino acid. The collapse retaining agent has excellent mud resistance and collapse retaining properties. The present invention does not use polyether macromonomers such as isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether and vinyl polyoxyethylene ether, thereby avoiding the introduction of polyether long side chains that are prone to physical adsorption and chemical intercalation; at the same time, physical adsorption can be reduced by introducing cationic and anionic groups; by adding amino acids, a rigid end-capping structure (benzene ring) is introduced to avoid chemical intercalation of the collapse retaining agent in layered clay minerals, thereby improving the tolerance of the collapse retaining agent to clay; the ester group formed by the esterification reaction can be hydrolyzed to form polyhydroxyl and carboxyl substances, which interact with the surface of cement particles to enhance the dispersion effect of cement, thereby making the concrete have excellent mud resistance and collapse retaining properties. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention provides a collapse-preventing agent in a first aspect. The collapse-preventing agent is prepared by polymerization of a double-terminated esterification functional monomer, an unsaturated carboxylic acid, an unsaturated ester and an unsaturated amide, wherein the double-terminated esterification functional monomer is obtained by esterification reaction of polyethylene glycol, methacrylic acid and an amino acid.

[0043] The slump retaining agent of the invention is polymerized by double-end esterification functional monomers, unsaturated carboxylic acids, unsaturated esters and unsaturated amides, and polyether macromonomers such as isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether and vinyl polyoxyethylene ether are not used, thereby avoiding the introduction of polyether long side chains that are prone to physical adsorption and chemical intercalation; and the double-end esterification functional monomers are obtained by esterification reaction of polyethylene glycol, methacrylic acid and amino acids, the anion groups in the unsaturated carboxylic acids can reduce the physical adsorption of clay in concrete, the amide groups in the unsaturated amides absorb water through hydrogen bonds, effectively prevent the coagulation of cement particles, and improve the slump retaining property of cement; the ester groups in the unsaturated esters can be hydrolyzed to form polyhydroxyl and carboxyl substances, and the hydrolysis products can interact with the surfaces of cement particles to enhance the dispersion effect of cement, so that the concrete has excellent mud resistance and slump retaining property.

[0044] In some embodiments, the amino acid includes phenylalanine and / or tyrosine, that is, the amino acid can be phenylalanine, tyrosine, or a combination of phenylalanine and tyrosine. Phenylalanine and tyrosine contain a rigid structure of a benzene ring, which can better avoid chemical intercalation of the collapse retaining agent in layered clay minerals through the steric hindrance effect, thereby further improving the tolerance of the collapse retaining agent to clay.

[0045] The present invention can further improve the mud resistance and collapse resistance of the collapse retaining agent by controlling the mass ratio of the double-terminated esterified functional monomer, the unsaturated carboxylic acid, the unsaturated ester and the unsaturated amide, as well as the mass ratio of the polyethylene glycol, the methacrylic acid and the amino acid, thereby making the concrete have better mud resistance and collapse resistance.

[0046] In some embodiments, the mass ratio of the double-capped esterification functional monomer, the unsaturated ester, the unsaturated carboxylic acid, and the unsaturated amide is (30-45): (3.5-6.5): (1-2): 1.

[0047] Illustratively, the mass ratio of the double-capped esterified functional monomer, the unsaturated ester, the unsaturated carboxylic acid, and the unsaturated amide can be 30:3.5:1:1, 30:4.5:1.5:1, 30:5:1.5:1, 35:4:1:1, 35:4:1.5:1, 35:4:2:1, 35:4.5:1:1, 35:5:1:1, 35:6:1.5:1, 35:6.5:2:1, 40:4:1:1, 40:4:1.5:1, 40:4:2:1, 40:4.5:1:1, 40:5:1:1, 40:6:1.5:1, 40:6.5:2:1, 45:3.5:1:1, 45:4.5:1.5:1, or 45:5:1.5:1, etc.

[0048] In some embodiments, the mass ratio of polyethylene glycol, amino acid and methacrylic acid is (9-18):(1.8-2.5):1.

[0049] Illustratively, the mass ratio of polyethylene glycol, amino acid and methacrylic acid can be 9:1.8:1, 12:1.8:1, 14:1.8:1, 16:1.8:1, 18:1.8:1, 9:2:1, 12:2:1, 14:2:1, 16:2:1, 18:2:1, 9:2.5:1, 12:2.5:1, 14:2.5:1, 16:2.5:1 or 18:2.5:1, etc.

[0050] In the present invention, the double-terminated esterification functional monomer includes a compound as shown in the following formula 1:

[0051] Formula 1;

[0052] In Formula 1, n = an integer from 16 to 35 (e.g., 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35), and R is a hydrogen atom or a hydroxyl group.

[0053] The double-terminated esterification functional monomer of the present invention has a zigzag chain structure, contains unsaturated functional groups, has copolymerization activity, and the rigid end-capping structure (benzene ring) introduced into the amino acid can protect the alkyl chain, prevent the alkyl chain of the collapse retaining agent from being chemically intercalated in the layered clay mineral, enhance the dispersion effect of cement, and make the concrete have excellent fluidity and collapse retention. The integer of n=16-35 can make the double-terminated esterification functional monomer have both excellent reactivity and dispersibility.

[0054] In the present invention, the unsaturated carboxylic acid includes the compound shown in Formula 2, the unsaturated ester includes the compound shown in Formula 3, and the unsaturated amide includes the compound shown in Formula 4, which can enhance the interaction between the slump retaining agent and cement particles and improve the dispersion effect of the slump retaining agent.

[0055] In some embodiments, the unsaturated carboxylic acid includes a compound represented by Formula 2:

[0056] Formula 2;

[0057] In Formula 2, R1, R2, and R3 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms (eg, 1, 2, 3, 4, 5), or a carboxyl group having 1 to 5 carbon atoms.

[0058] In some embodiments, the unsaturated ester includes a compound shown in Formula 3:

[0059] Formula 3;

[0060] In formula 3, R4, R5, and R6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms (e.g., 1, 2, 3, 4, 5), and R7 is independently an alkyl group having 1 to 5 carbon atoms (e.g., 1, 2, 3, 4, 5).

[0061] In some embodiments, the unsaturated amide includes a compound shown in Formula 4 below:

[0062] Formula 4;

[0063] In formula 4, R8, R9, R 10 , R 11 , R 12 Each is independently a hydrogen atom or an alkyl group having 1 to 5 (eg, 1, 2, 3, 4, 5) carbon atoms.

[0064] In some embodiments, the unsaturated carboxylic acid includes at least one of acrylic acid, crotonic acid, citraconic acid, maleic acid, methacrylic acid, itaconic acid or fumaric acid, which reduces the physical adsorption of clay in concrete while also having the advantages of easy availability of raw materials and low cost.

[0065] In some embodiments, the unsaturated ester includes at least one of hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate or hydroxypropyl methacrylate, which forms polyhydroxy and carboxyl substances when hydrolyzed, interacts with the surface of cement particles, enhances the dispersion effect of cement, and has the advantages of easy availability of raw materials and low cost.

[0066] In some embodiments, the unsaturated amide includes at least one of acrylamide or methacrylamide, which prevents the coagulation of cement particles and improves the slump retention of the slump retaining agent while having the advantages of easy availability of raw materials and low cost.

[0067] According to the technical solution of the present invention, the collapse-preventing agent includes a compound shown in Formula 5:

[0068] Formula 5;

[0069] In formula 5, n = an integer from 16 to 35 (e.g., 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35), m1 = an integer from 10 to 50 (e.g., 10, 15, 20, 25, 30, 35, 40, 45 or 50), m2 = an integer from 5 to 40 (e.g., 5, 10, 15, 20, 25, 3 0, 35, 35 or 40, etc.), m3 = an integer of 18 to 85 (such as 18, 25, 35, 45, 55, 65, 75 or 85, etc.), m4 = an integer of 6 to 30 (such as 6, 10, 15, 20, 25 or 30, etc.), R is a hydrogen atom or a hydroxyl group, R1, R2, and R3 are each independently a hydrogen atom, a C1 to C5 alkyl group, or a carboxyl group having 1 to 5 carbon atoms; R4, R5, R6, R8, R9, R 10 , R 11 , R 12 Each is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms (eg, 1, 2, 3, 4, 5); R7 is independently an alkyl group having 1 to 5 carbon atoms (eg, 1, 2, 3, 4, 5).

[0070] The present invention provides in a second aspect a method for preparing the collapse-preventing agent according to the first aspect, comprising the following steps:

[0071] 1) In parts by weight, 360-400 parts (such as 360 parts, 370 parts, 380 parts, 390 parts or 400 parts) of polyethylene glycol, 20-43 parts (such as 20 parts, 23 parts, 26 parts, 29 parts, 32 parts, 35 parts, 38 parts, 40 parts or 43 parts) of methacrylic acid, 40-90 parts (such as 40 parts, 50 parts, 60 parts, 70 parts, 80 parts or 90 parts) of amino acid, 11-25 parts (such as 11 parts, 13 parts, 16 parts, 19 parts, 22 parts or 25 parts) of catalyst, and 9-20 parts (such as 9 parts, 12 parts, 15 parts, 18 parts or 20 parts) of polymerization inhibitor are mixed, and esterification reaction is carried out under an inert atmosphere to obtain a double-terminated esterification functional monomer;

[0072] 2) Add 3.2~7.8 parts (such as 3.2 parts, 4 parts, 4.8 parts, 5.6 parts, 6.8 parts or 7.8 parts) of initiator, 1.6~8 parts (such as 1.6 parts, 2 parts, 4 parts, 6 parts or 8 parts) of chain transfer agent, 0.7~1.9 parts (such as 0.7 parts, 1 part, 1.4 parts, 1.6 parts or 1.9 parts) of reducing agent, 14~3 0 parts (such as 14 parts, 17 parts, 20 parts, 23 parts, 26 parts or 30 parts) of unsaturated carboxylic acid, 57-80 parts (such as 57 parts, 60 parts, 63 parts, 66 parts, 70 parts, 74 parts, 77 parts or 80 parts) of unsaturated ester, and 9-20 parts (such as 9 parts, 13 parts, 16 parts, 18 parts or 20 parts) of unsaturated amide are polymerized under an inert atmosphere to obtain a collapse retaining agent.

[0073] The collapse-preventing agent prepared by the preparation method of the present invention has excellent mud resistance and collapse-preventing properties, and the preparation method is simple in process and convenient for industrial production.

[0074] In some embodiments, in step (1) and step (2), the inert atmosphere includes nitrogen, argon, etc. Nitrogen or argon is used as the inert atmosphere to prevent oxygen from entering the reaction system, thereby avoiding oxygen from interfering with the esterification reaction, the polymerization reaction, or oxidizing the product.

[0075] In some embodiments, the catalyst may be an existing substance that can catalyze the esterification reaction, including but not limited to at least one of concentrated sulfuric acid, p-toluenesulfonic acid, dimethylaminopyridine or p-aminobenzenesulfonic acid, which helps to accelerate the esterification reaction.

[0076] In some embodiments, the inhibitor includes, but is not limited to, at least one of p-hydroxyanisole, hydroquinone, diphenol, or phenothiazine, which can effectively prevent side reactions initiated by free radicals.

[0077] In some embodiments, the average molecular weight of polyethylene glycol is 722-1558, which is beneficial to control the side chain length of the slump retaining agent and helps to improve the adsorption capacity and dispersion effect of the slump retaining agent on the surface of cement particles.

[0078] In some embodiments, the initiator includes at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate or azobisisobutyronitrile to better control the initiation and progress of the polymerization reaction.

[0079] In some embodiments, the reducing agent includes at least one of vitamin C, ferrous sulfate, cuprous sulfate, oxalic acid, sodium bisulfite or sodium sulfite. The reducing agent can react with the initiator to generate free radicals to promote the polymerization reaction.

[0080] In some embodiments, the chain transfer agent includes at least one of isopropanol, phosphorous acid, hypophosphorous acid, phosphite, hypophosphorous acid, sulfurous acid, bisulfite, dithionite, dithionite, metabisulfite, mercaptoethanol, thioglycolic acid, mercaptopropionic acid, thiomalic acid, 2-mercaptoethanesulfonic acid, thioglycolate, mercaptopropionic acid, thiomalate or 2-mercaptoethanesulfonic acid, which can better control the molecular weight of the collapse retaining agent and terminate the chain growth by transferring the terminal free radicals of the active chain.

[0081] In the present invention, step 2) further comprises adding water to the double-terminated esterification functional monomer, so that the polymerization reaction can be carried out more efficiently and stably.

[0082] In some embodiments, in step 2), the amount of water added is 400-430 parts.

[0083] In some embodiments, in step 1), in the esterification reaction, the reaction temperature is 105-120°C (such as 105°C, 110°C, 115°C or 120°C, etc.), and the reaction time is 7-11h (such as 7h, 8h, 9h, 10h or 11h, etc.).

[0084] In some embodiments, in step 2), the dripping time is 1 to 3.5 h (such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h or 3.5 h, etc.).

[0085] In some embodiments, in step 2), in the polymerization reaction, the reaction temperature is 55-60°C (such as 55°C, 57°C, 59°C or 60°C, etc.), and the reaction time is 2-6h (such as 2h, 3h, 4h, 5h or 6h, etc.), wherein the polymerization reaction time includes the dripping time.

[0086] The present invention controls the temperature and time of the esterification reaction, the transesterification reaction and the polymerization reaction within the above range, thereby ensuring a high conversion rate and reducing the generation of by-products. In addition, by controlling the dripping speed of the chain transfer agent, the reducing agent, the unsaturated carboxylic acid, the unsaturated ester and the unsaturated amide, the stability and uniformity of the polymerization reaction can be ensured, and local overheating or incomplete reaction can be avoided.

[0087] The present invention provides a concrete in a third aspect, the concrete comprising the collapse-preserving agent in the first aspect. The concrete prepared by using the collapse-preserving agent of the present invention has excellent mud resistance and collapse-preserving properties, and can effectively meet the demand for high-performance concrete in the modern construction market.

[0088] Hereinafter, the present invention will be further described in detail through specific examples.

[0089] Example 1

[0090] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0091] (1) 370 parts by weight of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 56 parts of tyrosine, 16 parts of p-toluenesulfonic acid, and 14 parts of hydroquinone were taken and subjected to esterification reaction at 110°C under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1415;

[0092] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 6 parts of hydrogen peroxide (mass fraction 27%) at 26° C., and dropwise add 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 19 parts of acrylic acid, 67 parts of hydroxyethyl acrylate, and 13 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 51720.

[0093] Example 2

[0094] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0095] (1) 360 parts by weight of polyethylene glycol (average molecular weight of 800), 38 parts of methacrylic acid, 75 parts of phenylalanine, 17 parts of dimethylaminopyridine, and 13 parts of p-hydroxyanisole were taken and subjected to esterification reaction at 110° C. under nitrogen protection for 7 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1010;

[0096] (2) Add 420 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 5.2 parts of ammonium persulfate at 26° C., and dropwise add 4.9 parts of thioglycolic acid, 0.8 parts of ferrous sulfate, 16 parts of crotonic acid, 63 parts of hydroxymethyl acrylate, and 16 parts of methacrylamide. The duration of the dropwise addition is 3.5 hours. Then, the mixture is kept at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 59340.

[0097] Example 3

[0098] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0099] (1) 370 parts by weight of polyethylene glycol (average molecular weight of 1000), 32 parts of methacrylic acid, 67 parts of tyrosine, 18 parts of p-aminobenzenesulfonic acid, and 15 parts of diphenol were subjected to esterification reaction at 110°C under nitrogen protection for 8 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1208;

[0100] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 5.9 parts of potassium persulfate at 26° C., and dropwise add 7.1 parts of mercaptopropionic acid, 1.2 parts of oxalic acid, 21 parts of citraconic acid, 69 parts of hydroxypropyl acrylate, and 11 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept warm at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 60475.

[0101] Example 4

[0102] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0103] (1) By weight, 400 parts of polyethylene glycol (average molecular weight of 1500), 23 parts of methacrylic acid, 48 parts of tyrosine, 16 parts of concentrated sulfuric acid, and 14 parts of hydroquinone were taken and subjected to esterification reaction at 110°C under nitrogen protection for 11 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1710;

[0104] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 5.7 parts of hydrogen peroxide (mass fraction 27%) at 26° C., and dropwise add 6.3 parts of thiomalic acid, 1.3 parts of vitamin C, 20 parts of methacrylic acid, 68 parts of hydroxymethyl methacrylate, and 17 parts of acrylamide; the duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 58402.

[0105] Example 5

[0106] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0107] (1) By weight, 380 parts of polyethylene glycol (average molecular weight of 1000), 33 parts of methacrylic acid, 60 parts of tyrosine, 17 parts of concentrated sulfuric acid, and 15 parts of phenothiazine were taken and subjected to esterification reaction at 110°C under nitrogen protection for 8 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1211;

[0108] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 6.6 parts of azobisisobutyronitrile at 26°C, and dropwise add 6.5 parts of dithionite, 1.4 parts of sodium sulfite, 22 parts of maleic acid, 66 parts of hydroxyethyl acrylate, and 14 parts of methacrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60°C for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 53021.

[0109] Example 6

[0110] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0111] (1) By weight, 370 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 51 parts of phenylalanine, 19 parts of p-toluenesulfonic acid, and 16 parts of hydroquinone were taken and subjected to esterification reaction at 110°C under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1412;

[0112] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 6.2 parts of sodium persulfate at 26° C., and dropwise add 7.4 parts of 2-mercaptoethanesulfonic acid, 1.5 parts of sodium bisulfite, 23 parts of fumaric acid, 70 parts of hydroxyethyl methacrylate, and 16 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept warm at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 51476.

[0113] Example 7

[0114] The collapse-preventing agent of the present embodiment is prepared by the following steps:

[0115] (1) By weight, 380 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 57 parts of tyrosine, 18 parts of dimethylaminopyridine, and 15 parts of phenothiazine were taken and subjected to esterification reaction at 110°C under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1417;

[0116] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 6.1 parts of hydrogen peroxide (mass fraction 27%) at 26° C., and dropwise add 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 22 parts of itaconic acid, 76 parts of hydroxypropyl methacrylate, and 15 parts of methacrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept warm at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 51626.

[0117] Comparative Example 1

[0118] This comparative example uses a commercially available polycarboxylic acid collapse-preventing agent of model M23 produced by Jiangsu Aolaite New Materials Co., Ltd.

[0119] Comparative Example 2

[0120] This comparative example uses a commercially available polycarboxylic acid collapse-preventing agent of model KH-218 produced by Wuhan Huaxuan High-tech Industry Co., Ltd.

[0121] Comparative Example 3

[0122] The preparation method of the collapse-preserving agent provided in this comparative example is basically the same as that of Example 1, except that tyrosine is not used in step (1).

[0123] The specific preparation method comprises the following steps:

[0124] (1) By weight, 370 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 16 parts of p-toluenesulfonic acid, and 14 parts of hydroquinone were taken and subjected to esterification reaction at 110°C under nitrogen protection for 9 hours to obtain a single-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1260;

[0125] (2) Add 430 parts of water to the double-terminated esterified functional monomer obtained in step (1), add 6 parts of hydrogen peroxide (mass fraction 27%) at 26° C., and dropwise add 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 19 parts of acrylic acid, 67 parts of hydroxyethyl acrylate, and 13 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60° C. for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 46916.

[0126] Comparative Example 4

[0127] The preparation method of the collapse retaining agent provided in this comparative example is basically the same as that of Example 1, except that in step (2), 1 / 3 of the mass of the double-terminated esterified functional monomer is replaced by isobutylene polyethylene glycol ether (HPEG-2400) with an average molecular weight of 2400.

[0128] The specific preparation method comprises the following steps:

[0129] (1) By weight, 370 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 56 parts of tyrosine, 16 parts of p-toluenesulfonic acid, and 14 parts of hydroquinone were mixed and subjected to esterification reaction at 110° C. under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1415;

[0130] (2) Take 320 parts of the double-terminated esterified functional monomer obtained in step (1), 160 parts of isobutylene polyethylene glycol ether (HPEG-2400), add 430 parts of water, add 6 parts of hydrogen peroxide (mass fraction 27%) at 26°C, and add dropwise 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 19 parts of acrylic acid, 67 parts of hydroxyethyl acrylate, and 13 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60°C for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 58316.

[0131] Comparative Example 5

[0132] The preparation method of the water reducer provided in this comparative example is basically the same as that of comparative example 4, except that in step (2), isopentenyl polyethylene glycol ether (TPEG-2400) with a molecular weight of 2400 is used to replace 1 / 3 of the double-terminated esterified functional monomer for synthesis.

[0133] The specific preparation method comprises the following steps:

[0134] (1) By weight, 370 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 56 parts of tyrosine, 16 parts of p-toluenesulfonic acid, and 14 parts of hydroquinone were mixed and subjected to esterification reaction at 110° C. under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1415;

[0135] (2) Take 320 parts of the double-terminated esterified functional monomer obtained in step (1), 160 parts of isopentyl polyethylene glycol ether (TPEG-2400), add 430 parts of water, add 6 parts of hydrogen peroxide (27%) at 26°C, and add dropwise 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 19 parts of acrylic acid, 67 parts of hydroxyethyl acrylate, and 13 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60°C for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 59734.

[0136] Comparative Example 6

[0137] The preparation method of the water reducer provided in this comparative example is basically the same as that of comparative example 4, except that in step (2), vinyl polyoxyethylene ether (VPEG-3000) with a molecular weight of 3000 is used to replace 1 / 3 of the mass of the double-terminated esterified functional monomer for synthesis.

[0138] The specific preparation method comprises the following steps:

[0139] (1) By weight, 370 parts of polyethylene glycol (average molecular weight of 1200), 27 parts of methacrylic acid, 56 parts of tyrosine, 16 parts of p-toluenesulfonic acid, and 14 parts of hydroquinone were mixed and subjected to esterification reaction at 110° C. under nitrogen protection for 9 hours to obtain a double-terminated esterification functional monomer. The weight average molecular weight of the product measured by GPC was 1415;

[0140] (2) Take 320 parts of the double-terminated esterified functional monomer obtained in step (1), 160 parts of vinyl polyoxyethylene ether (VPEG-3000), add 430 parts of water, add 6 parts of hydrogen peroxide (27%) at 26°C, and add dropwise 6 parts of thioglycolic acid, 1.1 parts of vitamin C, 19 parts of acrylic acid, 67 parts of hydroxyethyl acrylate, and 13 parts of acrylamide. The duration of the dropwise addition is 3.5 hours, and then the mixture is kept at 60°C for 1 hour to obtain a collapse retaining agent. The weight average molecular weight of the product measured by GPC is 64316.

[0141] Application Examples

[0142] Southern PO 42.5 cement, machine-made mountain sand with a fineness modulus of 2.9 (fineness modulus (MB value) of 2.8), crushed stone 1 with a nominal particle size of 5mm~10mm and crushed stone 2 with a nominal particle size of 10mm~20mm were used as raw materials and mixed to obtain concrete premix. The slump retaining agent prepared in the embodiment and the comparative example was respectively mixed with the commercially available SP-200 water reducing agent in a mass ratio of 3:7 to form an admixture, and then the admixture and the concrete premix were mixed to obtain concrete. The admixture was added in an amount of 0.30% (solid content) of the mass of Southern PO42.5 cement. According to the detection method provided in GB8076-2008 "Concrete Admixtures", the concrete expansion at the initial, 1h, 2h, and 3h of the concrete was tested, which is usually used to evaluate the change of the slump retaining property and fluidity of the concrete over time. The results are shown in Table 2.

[0143] The raw materials and mix ratio of the concrete used in the test are shown in Table 1:

[0144] Table 1

[0145]

[0146] Table 2

[0147]

[0148] It can be seen from the test data in Table 2 that, under the condition that the water reducing agent dosage in each embodiment and the comparative example is the same, compared with comparative examples 1 to 2, the expansion of the concrete to which the slump retaining agent of embodiments 1 to 7 of the present invention is added is stably maintained within 500 to 520 mm within 180 min, and the slump retaining performance of the concrete is excellent, while the concrete to which the slump retaining agent of comparative examples 1 to 2 is added has obvious insufficient fluidity, which is not conducive to construction.

[0149] In Comparative Example 3, tyrosine was not used, and polyethylene glycol and methacrylic acid were subjected to an esterification reaction to form a single-terminated esterified monomer. The long side chain of the slump retaining agent polymer lacked the rigid end-capping of tyrosine, so that the long side chain of the slump retaining agent polymer was chemically intercalated with the layered clay minerals in the cement, and could not effectively act on the surface of the cement particles to improve the dispersion performance. Therefore, the loss of concrete over time was relatively large.

[0150] In comparative example 4, isobutylene polyethylene glycol ether (HPEG-2400) was used to replace 1 / 3 of the mass of the double-terminated esterified functional monomer, in comparative example 5, isopentenyl polyethylene glycol ether (TPEG-2400) was used to replace 1 / 3 of the mass of the double-terminated esterified functional monomer, and in comparative example 6, vinyl polyoxyethylene ether (VPEG-3000) was used to replace 1 / 3 of the mass of the double-terminated esterified functional monomer for synthesis. Comparative examples 4-6 all introduced long polyether side chains that were prone to physical adsorption and chemical intercalation, and the slump retaining agent was severely adsorbed by clay, resulting in large initial fluidity and time loss of the concrete.

[0151] In summary, the collapse-preventing agent of the present invention can be effectively used as a concrete collapse-preventing agent and has excellent anti-mud effect and collapse-preventing effect.

[0152] Among them, it should be explained at the end that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or part or all of the technical features can be replaced by equivalents. These modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. A collapse-preventing agent, characterized in that: The collapse-preventing agent is polymerized from double-terminated esterified functional monomers, unsaturated carboxylic acids, unsaturated esters and unsaturated amides; The double-terminated esterification functional monomer is obtained by esterification reaction of polyethylene glycol, methacrylic acid and amino acid.

2. The collapse-preventing agent according to claim 1, characterized in that The amino acids include phenylalanine and / or tyrosine.

3. The collapse-preventing agent according to claim 1, characterized in that: The mass ratio of the double-terminated esterification functional monomer, the unsaturated ester, the unsaturated carboxylic acid and the unsaturated amide is (30-45): (3.5-6.5): (1-2): 1; and / or, The mass ratio of the polyethylene glycol, amino acid and methacrylic acid is (9-18):(1.8-2.5):

1.

4. The collapse-preventing agent according to claim 1, characterized in that: The double-terminated esterification functional monomer includes a compound shown in the following formula 1: Formula 1; In Formula 1, n=16-35, R is a hydrogen atom or a hydroxyl group; and / or, The unsaturated carboxylic acid includes a compound shown in Formula 2: Formula 2; In Formula 2, R1, R2, and R3 are each independently a hydrogen atom, a C1-C5 alkyl group, or a carboxyl group having 1 to 5 carbon atoms; and / or, The unsaturated ester includes a compound shown in the following formula 3: Formula 3; In Formula 3, R4, R5, and R6 are each independently a hydrogen atom or a C1-C5 alkyl group, and R7 is independently a C1-C5 alkyl group; and / or, The unsaturated amide includes a compound shown in the following formula 4: Formula 4; In formula 4, R8, R9, R 10 , R 11 , R 12 Each is independently a hydrogen atom or a C1~C5 alkyl group.

5. The collapse-preventing agent according to claim 4, characterized in that: The unsaturated carboxylic acid comprises at least one of acrylic acid, crotonic acid, citraconic acid, maleic acid, methacrylic acid, itaconic acid or fumaric acid; and / or, The unsaturated ester comprises at least one of hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate or hydroxypropyl methacrylate; and / or, The unsaturated amide includes at least one of acrylamide or methacrylamide.

6. The collapse-preventing agent according to claim 1, characterized in that: The collapse-preserving agent includes a compound shown in Formula 5: Formula 5; In formula 5, n=16-35, m1=10-50, m2=5-40, m3=18-85, m4=6-30, R is a hydrogen atom or a hydroxyl group, R1, R2, and R3 are each independently a hydrogen atom, a C1-C5 alkyl group, or a carboxyl group having 1 to 5 carbon atoms; R4, R5, R6, R8, R9, and R 10 , R 11 , R 12 Each is independently a hydrogen atom or a C1~C5 alkyl group; R7 is independently a C1~C5 alkyl group.

7. The collapse-preventing agent according to claim 1, characterized in that: The weight average molecular weight of the collapse retaining agent is 51000-61000.

8. A method for preparing the collapse retaining agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Mix 360-400 parts of polyethylene glycol, 20-43 parts of methacrylic acid, 40-90 parts of amino acid, 11-25 parts of catalyst and 9-20 parts of inhibitor by weight, and carry out esterification reaction under an inert atmosphere to obtain a double-terminated esterification functional monomer; 2) 3.2-7.8 parts of initiator, 1.6-8 parts of chain transfer agent, 0.7-1.9 parts of reducing agent, 14-30 parts of unsaturated carboxylic acid, 57-80 parts of unsaturated ester and 9-20 parts of unsaturated amide are added dropwise to the double-terminated esterified functional monomer, and a polymerization reaction is carried out under an inert atmosphere to obtain the collapse retaining agent.

9. The preparation method according to claim 8, characterized in that: In step 1), in the esterification reaction, the reaction temperature is 105-120°C and the reaction time is 7-11h; and / or, In step 2), the dripping time is 1 to 3.5 hours; and / or, In step 2), in the polymerization reaction, the reaction temperature is 55-60° C. and the reaction time is 2-6 hours.

10. A concrete, characterized in that: The concrete comprises the collapse retaining agent according to any one of claims 1 to 7.

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