Composite polycarboxylic acid water reducing agent and preparation method thereof

Abstract

The application discloses a composite polycarboxylic acid water reducing agent and a preparation method thereof, and relates to the technical field of composite polycarboxylic acid water reducing agents. The composite polycarboxylic acid water reducing agent is composed of the following components in a mass percentage: polycarboxylic acid water reducing agent mother liquor: 60-85%; slow-release slump retaining component: 5-20%; viscosity adjusting component: 3-15%; functional adjusting component: 0.1-5%; and the balance is water. The polycarboxylic acid mother liquor containing multiple active groups in the main chain provides an initial high water reducing rate, and the special slump retaining component with slow-release adsorption characteristics is used, so that the slump loss is basically zero for more than 2 hours, and the slump loss problem under high temperature and long distance transportation is solved. The modified lignin sulfonate is introduced as the viscosity adjusting component, which can effectively improve the cohesiveness and fluidity of low water-binder ratio concrete, so that the concrete is more easily pumped and constructed, and is particularly suitable for self-compacting concrete.

Description

Technical Field

[0001] This invention relates to the field of composite polycarboxylate superplasticizer technology, specifically to a composite polycarboxylate superplasticizer and its preparation method. Background Technology

[0002] Polycarboxylate superplasticizers have become an indispensable key material in modern concrete engineering due to their advantages such as high water reduction rate, low dosage, and good environmental performance. However, traditional polycarboxylate superplasticizers still have some shortcomings in practical applications: 1) Their adaptability to cement is sometimes poor, especially when different types of cement or when a large amount of mineral admixtures are added, resulting in large performance fluctuations; 2) The slump loss of concrete is relatively fast, especially under high temperature environments, making it difficult to meet the requirements of long-distance transportation or long-term construction; 3) When preparing self-compacting or high-strength concrete with low water-cement ratio and high viscosity, it may cause an increase in viscosity, affecting workability.

[0003] To address these issues, a common approach is to use them in combination with retarders and ordinary slump retainers. However, simple physical compounding often suffers from poor synergistic effects and unstable performance. For example, conventional retarders and slump retainers may excessively delay setting time or compete with the main water-reducing agent molecules for adsorption, affecting initial dispersion. Furthermore, existing technologies lack functional components that can effectively adjust concrete viscosity without significantly impacting strength and durability.

[0004] Therefore, developing a composite polycarboxylate superplasticizer with high water reduction rate, excellent slump retention, strong viscosity adjustment capability, wide adaptability and stable performance is of great significance for promoting the development of high-performance concrete technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite polycarboxylate superplasticizer and its preparation method, solving the problems mentioned in the background section. To achieve the above objectives, this invention is implemented through the following technical solution: A composite polycarboxylate superplasticizer, comprising the following components by mass percentage: Polycarboxylate superplasticizer mother liquor: 60%-85%; Slow-release slump-retaining components: 5%-20%; Viscosity conditioning components: 3%-15%; Functional regulating components: 0.1%-5%; The remainder is water; The polycarboxylate superplasticizer mother liquor is obtained by copolymerization of raw materials including the following monomers in the presence of an initiator and a chain transfer agent: unsaturated polyether macromonomer, unsaturated carboxylic acid monomer, unsaturated sulfonate monomer, and unsaturated ester monomer.

[0006] Preferably, the unsaturated polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether (TPEG), methyl allyl alcohol polyoxyethylene ether (HPEG) or vinyl polyoxyethylene ether (VPEG), with a molecular weight of 2000-3000.

[0007] Preferably, the unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, and maleic anhydride; the unsaturated sulfonate monomer is at least one of acrylamide methylpropanesulfonic acid (AMPS) and sodium methacrylate sulfonate (MAS); and the unsaturated ester monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl methacrylate.

[0008] Preferably, the sustained-release slump-preserving component is a compound having the structure of formula (I): R1-O-(CH2CH2O)m-(CH2CH(CH3)O)n-SO3M (I) Wherein, R1 is a C8-C18 alkyl or alkenyl group, m is an integer from 10 to 50, n is an integer from 0 to 10, and M is Na+, K+, or NH4+.

[0009] Preferably, the viscosity-adjusting component is a lignin sulfonate that has undergone oxidative degradation and sulfonylation modification, with a weight-average molecular weight of 5000-20000.

[0010] Preferably, the functional regulating component includes an antifoaming agent and a preservative; the antifoaming agent is an organosilicon antifoaming agent or a polyether-modified polysiloxane antifoaming agent; the preservative is at least one of isothiazolinones and benzisothiazolinones.

[0011] A method for preparing composite polycarboxylate superplasticizer, S1. Preparation of polycarboxylate superplasticizer mother liquor: Add water and unsaturated polyether macromonomer to a reaction vessel, stir to dissolve and heat to 55-65℃; prepare a mixed aqueous solution A with unsaturated carboxylate monomer, unsaturated sulfonate monomer, unsaturated ester monomer, initiator, chain transfer agent and some water; prepare solution B with the remaining initiator and some water; add mixed aqueous solution A dropwise at a uniform rate over 2-4 hours, while simultaneously starting to add solution B dropwise, controlling the dropwise addition time to 3-5 hours; after the dropwise addition is complete, keep warm and mature for 1-3 hours, cool to below 40℃, and neutralize with alkaline solution to pH=6-7 to obtain polycarboxylate superplasticizer mother liquor; S2. Composite: Under stirring conditions, add the slow-release slump-retaining component, viscosity-modifying component and functional-modifying component sequentially to the polycarboxylate superplasticizer mother liquor obtained in step S1, and continue stirring for 1-2 hours until the mixture is uniform. S3. Filtration and Packaging: The composite liquid obtained in step S2 is filtered through a filter to remove mechanical impurities, thereby obtaining the finished composite polycarboxylate superplasticizer.

[0012] Preferably, in step S1, the initiator is a redox initiation system consisting of at least two of ammonium persulfate, potassium persulfate, vitamin C, and hydrogen peroxide; and the chain transfer agent is at least one of mercaptopropionic acid, mercaptoethanol, and dodecyl mercaptan.

[0013] Preferably, in step S1, the molar ratio of the monomers is: unsaturated polyether macromonomer: unsaturated carboxylic acid monomer: unsaturated sulfonate monomer: unsaturated ester monomer = 1:(2.0-4.0):(0.1-0.5):(0.05-0.3); the total amount of initiator is 0.5%-2.0% of the total monomer mass; and the amount of chain transfer agent is 0.3%-1.5% of the total monomer mass.

[0014] The advantages of this application are: 1. The polycarboxylic acid mother liquor with multiple active groups in the main chain provides an initial high water reduction rate. Combined with a special slump-preserving component with slow-release adsorption properties, it can achieve virtually no slump loss for more than 2 hours, solving the problem of slump loss under high temperature and long-distance transportation.

[0015] 2. The introduction of modified lignin sulfonate as a viscosity modifier can effectively improve the cohesiveness and fluidity of low water-cement ratio concrete, making it easier to pump and construct, and is particularly suitable for self-compacting concrete.

[0016] 3. The multifunctional group design, including sulfonic acid and ester groups, enhances compatibility with different types of cement and admixtures. The addition of functional components ensures the product's storage stability and the controllability of the air content in concrete.

[0017] 4. The mother liquor synthesis adopts mature aqueous solution free radical copolymerization, and the post-composite process is simple, easy to realize industrial production, and the product quality is stable. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] A composite polycarboxylate superplasticizer, comprising the following components by mass percentage: Polycarboxylate superplasticizer mother liquor: 60%-85%; Slow-release slump-retaining components: 5%-20%; Viscosity conditioning components: 3%-15%; Functional regulating components: 0.1%-5%; The remainder is water; The polycarboxylate superplasticizer mother liquor is obtained by copolymerizing raw materials including the following monomers in the presence of an initiator and a chain transfer agent: unsaturated polyether macromonomer, unsaturated carboxylic acid monomer, unsaturated sulfonate monomer, and unsaturated ester monomer.

[0020] The unsaturated polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether (TPEG), methyl allyl alcohol polyoxyethylene ether (HPEG) or vinyl polyoxyethylene ether (VPEG), with a molecular weight of 2000-3000.

[0021] The unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, and maleic anhydride; the unsaturated sulfonate monomer is at least one of acrylamide methylpropanesulfonic acid (AMPS) and sodium methacrylate sulfonate (MAS); and the unsaturated ester monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl methacrylate.

[0022] The sustained-release slump-retaining component is a compound having the structure of formula (I): R1-O-(CH2CH2O)m-(CH2CH(CH3)O)n-SO3M (I) Wherein, R1 is a C8-C18 alkyl or alkenyl group, m is an integer from 10 to 50, n is an integer from 0 to 10, and M is Na+, K+, or NH4+.

[0023] The viscosity modifier is a lignin sulfonate that has undergone oxidative degradation and sulfonylation modification, with a weight-average molecular weight of 5,000-20,000.

[0024] The functional regulating components include defoamers and preservatives; the defoamer is an organosilicon defoamer or a polyether-modified polysiloxane defoamer; the preservative is at least one of isothiazolinones and benzisothiazolinones.

[0025] A method for preparing composite polycarboxylate superplasticizer, S1. Preparation of polycarboxylate superplasticizer mother liquor: Add water and unsaturated polyether macromonomer to a reactor, stir to dissolve and heat to 55-65℃; prepare a mixed aqueous solution A by mixing unsaturated carboxylic acid monomer, unsaturated sulfonate monomer, unsaturated ester monomer, initiator, chain transfer agent and a portion of water; prepare solution B by mixing the remaining initiator and a portion of water; add mixed aqueous solution A dropwise at a uniform rate over 2-4 hours, while simultaneously starting to add solution B dropwise, controlling the dropwise addition time to 3-5 hours; after the dropwise addition is complete, keep warm and mature for 1-3 hours, cool to below 40℃, and neutralize with an alkaline solution to pH=6-7 to obtain polycarboxylate superplasticizer mother liquor; the initiator is an oxidation-reduction initiation system composed of at least two of ammonium persulfate, potassium persulfate, vitamin C, and hydrogen peroxide; the chain transfer agent is at least one of mercaptopropionic acid, mercaptoethanol, and dodecyl mercaptan, and the monomer molar ratio is: unsaturated polyether macromonomer: unsaturated carboxylic acid monomer: unsaturated sulfonate monomer: unsaturated ester monomer = 1:(2.0-4.0):(0.1-0.5):(0.05-0.3); the total amount of initiator is 0.5%-2.0% of the total mass of monomers; the amount of chain transfer agent is 0.3%-1.5% of the total mass of monomers. S2. Composite: Under stirring conditions, add the slow-release slump-retaining component, viscosity-modifying component and functional-modifying component sequentially to the polycarboxylate superplasticizer mother liquor obtained in step S1, and continue stirring for 1-2 hours until the mixture is uniform. S3. Filtration and Packaging: The composite liquid obtained in step S2 is filtered through a filter to remove mechanical impurities, thus obtaining the finished composite polycarboxylate superplasticizer.

[0026] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite polycarboxylate superplasticizer, characterized in that, It consists of the following components by mass percentage: Polycarboxylate superplasticizer mother liquor: 60%-85%; Slow-release slump-retaining components: 5%-20%; Viscosity conditioning components: 3%-15%; Functional regulating components: 0.1%-5%; The remainder is water; The polycarboxylate superplasticizer mother liquor is obtained by copolymerization of raw materials including the following monomers in the presence of an initiator and a chain transfer agent: unsaturated polyether macromonomer, unsaturated carboxylic acid monomer, unsaturated sulfonate monomer, and unsaturated ester monomer.

2. The composite polycarboxylate superplasticizer according to claim 1, characterized in that: The unsaturated polyether macromonomer is at least one of isopentenyl alcohol polyoxyethylene ether (TPEG), methyl allyl alcohol polyoxyethylene ether (HPEG) or vinyl polyoxyethylene ether (VPEG), with a molecular weight of 2000-3000.

3. The composite polycarboxylate superplasticizer according to claim 1, characterized in that: The unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, and maleic anhydride; the unsaturated sulfonate monomer is at least one of acrylamide methylpropanesulfonic acid (AMPS) and sodium methacrylate sulfonate (MAS); and the unsaturated ester monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, and methyl methacrylate.

4. The composite polycarboxylate superplasticizer according to claim 1, characterized in that: The sustained-release slump-preserving component is a compound having the structure of formula (I): R1-O-(CH2CH2O)m-(CH2CH(CH3)O)n-SO3M (I) Wherein, R1 is a C8-C18 alkyl or alkenyl group, m is an integer from 10 to 50, n is an integer from 0 to 10, and M is Na+, K+, or NH4+.

5. The composite polycarboxylate superplasticizer according to claim 1, characterized in that: The viscosity-adjusting component is a lignin sulfonate that has undergone oxidative degradation and sulfonylation modification, with a weight-average molecular weight of 5000-20000.

6. The composite polycarboxylate superplasticizer according to claim 1, characterized in that: The functional regulating components include defoamers and preservatives; the defoamer is an organosilicon defoamer or a polyether-modified polysiloxane defoamer; the preservative is at least one of isothiazolinones and benzisothiazolinones.

7. A method for preparing the composite polycarboxylate superplasticizer according to any one of claims 1-6, characterized in that: S1. Preparation of polycarboxylate superplasticizer mother liquor: Add water and unsaturated polyether macromonomer to a reaction vessel, stir to dissolve and heat to 55-65℃; prepare a mixed aqueous solution A with unsaturated carboxylate monomer, unsaturated sulfonate monomer, unsaturated ester monomer, initiator, chain transfer agent and some water; prepare solution B with the remaining initiator and some water; add mixed aqueous solution A dropwise at a uniform rate over 2-4 hours, while simultaneously starting to add solution B dropwise, controlling the dropwise addition time to 3-5 hours; after the dropwise addition is complete, keep warm and mature for 1-3 hours, cool to below 40℃, and neutralize with alkaline solution to pH=6-7 to obtain polycarboxylate superplasticizer mother liquor; S2. Composite: Under stirring conditions, add the slow-release slump-retaining component, viscosity-modifying component and functional-modifying component sequentially to the polycarboxylate superplasticizer mother liquor obtained in step S1, and continue stirring for 1-2 hours until the mixture is uniform. S3. Filtration and Packaging: The composite liquid obtained in step S2 is filtered through a filter to remove mechanical impurities, thereby obtaining the finished composite polycarboxylate superplasticizer.

8. The method for using the composite polycarboxylate superplasticizer according to claim 7, characterized in that: In step S1, the initiator is a redox initiation system consisting of at least two of ammonium persulfate, potassium persulfate, vitamin C, and hydrogen peroxide; the chain transfer agent is at least one of mercaptopropionic acid, mercaptoethanol, and dodecyl mercaptan.

9. The method for using the composite polycarboxylate superplasticizer according to claim 7, characterized in that: In step S1, the molar ratio of the monomers is: unsaturated polyether macromonomer: unsaturated carboxylic acid monomer: unsaturated sulfonate monomer: unsaturated ester monomer = 1:(2.0-4.0):(0.1-0.5):(0.05-0.3); the total amount of initiator is 0.5%-2.0% of the total monomer mass; and the amount of chain transfer agent is 0.3%-1.5% of the total monomer mass.