Preparation method of modified polycarboxylic acid grinding aid

Abstract

The invention discloses a preparation method of a modified polycarboxylic acid grinding aid, and the modified polycarboxylic acid grinding aid is prepared from the following raw materials in parts by weight: 80 to 120 parts of unsaturated polyether, 10 to 20 parts of acrylic acid, 5 to 15 parts of 2-acrylamide-2-methylpropanesulfonic acid, 3 to 8 parts of phosphate ester monomer, 3 to 8 parts of modified nano SiO2 and 0.3 to 0.7 part of initiator. The initiator comprises persulfate, ascorbic acid and ferrous sulfate according to a molar ratio of 3: 1: 0.1, and the preparation method of the modified polycarboxylic acid grinding aid comprises the following steps: (a) mixing unsaturated polyether, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and a phosphate monomer at 35-40 DEG C under the protection of nitrogen; (b) dropwise adding an initiator solution in three stages, adding persulfate in the first stage, adding ferrous sulfate in the second stage, and adding ascorbic acid in the third stage; and (c) reacting until the conversion rate is greater than or equal to 80%, adding the modified nano SiO2, and continuously reacting until the viscosity of the system reaches 200-300 mPa.s. The low-temperature polymerization can improve the dispersion efficiency and the stability of the grinding aid by increasing the mixing amount.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grinding aids, in particular to a preparation method of modified polycarboxylic acid grinding aid. BACKGROUND

[0002] Cement grinding aid is a chemical additive that can improve the grinding effect and performance of cement, can greatly reduce the electrostatic adsorption balling phenomenon formed in the grinding process, and can also significantly improve the fluidity of cement, improve the grinding effect of the mill and the powder selection efficiency of the powder concentrator, thereby reducing the grinding energy consumption.

[0003] Traditional cement grinding aids include liquid grinding aids and solid grinding aids, and the basic components of most of them belong to organic surface active substances, mainly including amine, alcohol, alcohol amine, lignin sulfonate, fatty acid and its salt, alkyl sulfonate, etc. Common organic amine monomers include diethanolamine, diisopropanolamine, triethanolamine, triisopropanolamine, diethanol monoisopropanolamine, monoethanol diisopropanolamine, and ethoxylated products of polyamine monomers, etc. Patents CN105271876B, CN108147699A, CN108147692A, etc. disclose such grinding aids. The grinding aids of high molecular polymers use unsaturated organic amine, unsaturated carboxylate, unsaturated carboxylate, and unsaturated amide monomers as polymerization monomers, and through free radical polymerization reaction, the carboxylic acid group, alcohol amine group, carboxylic acid ester group, amide group, and polyether polyol group are chemically bonded together. Patents CN102653460B, CN102134300B, CN105669909B, etc. disclose such grinding aids.

[0004] Although the above-mentioned grinding aids show good grinding effect in the cement grinding process, they have poor dispersing effect and cannot be solved by increasing the dosage, and have poor synergy with other additives and poor stability. SUMMARY

[0005] The present application aims to provide a preparation method of modified polycarboxylic acid grinding aid to solve the problems in the background art.

[0006] To achieve the above object, the present application provides the following technical scheme: a preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprising the following raw materials by weight: 80-120 parts of unsaturated polyether, 10-20 parts of acrylic acid, 5-15 parts of 2-acrylamide-2-methylpropane sulfonic acid, 3-8 parts of phosphate monomer, 3-8 parts of modified nano-SiO2, and 0.3-0.7 parts of initiator, wherein the initiator comprises persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, and the preparation steps of the modified polycarboxylic acid grinding aid are as follows: (a) under nitrogen protection at 35-40°C, the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate monomer are mixed;

[0007] (b) the initiator solution is added dropwise in three stages, the first stage is to add the persulfate, the second stage is to add the ferrous sulfate, and the third stage is to add the ascorbic acid;

[0008] (c) when the conversion rate is greater than or equal to 80%, the modified nano-SiO2 is added, and the reaction is continued until the viscosity of the system reaches 200-300 mPa·s.

[0009] Preferably, the unsaturated polyether is at least one of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, isobutenyl alcohol polyoxyethylene ether and isoamylenol polyoxyethylene ether.

[0010] Preferably, the phosphate monomer is one of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate, 3-methacryloyloxypropyl phosphate, acryloyloxyethyl phosphate and 2-acryloyloxyethyl phosphate.

[0011] Preferably, the persulfate is at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0012] Preferably, the modified nano-SiO2 is a product modified by one of aminosilane, epoxy silane and methacryloyloxy silane.

[0013] The present application has the following beneficial effects:

[0014] 1. The present application introduces phosphate groups and sulfonic acid groups on the basis of unsaturated polyether, and the three functional groups are designed in cooperation, the main chain skeleton provides steric hindrance effect, the cement particle agglomeration is inhibited, the adsorption capacity of the sulfonic acid groups to the cement particles is enhanced, the stability of the grinding aid is improved, the phosphate groups chelate Ca 2+ , the cement particle surface charge neutralization is reduced, and the dispersion efficiency is improved.

[0015] 2. The initiator is added in the present application to form a low-temperature oxidation-reduction system, the polymerization reaction rate is controlled, the polymerization reaction temperature is reduced to below 35°C (the traditional process is greater than or equal to 60°C), and the thermal decomposition of the functional groups is reduced.

[0016] 3. The application is to add modified nano-SiO2 in the middle of the polymerization reaction, so that it participates in the free radical chain growth, enhances its chemical bonding ability with the polymer, and forms a polymer-nanoparticle interpenetrating network. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0018] The substances used in the application are all commercially available products, such as ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, and iso-pentenyl alcohol polyoxyethylene ether produced by Guangdong Aoke Chemical Co., Ltd.

[0019] A preparation method of a modified polycarboxylic acid grinding aid, each embodiment is respectively weighed according to the raw materials and the proportion in Table 1.

[0020]

[0021] Embodiment 1: A preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprises the following raw materials in parts by weight: 80 parts of unsaturated polyether, 14 parts of acrylic acid, 11 parts of 2-acrylamide-2-methylpropane sulfonic acid, 3 parts of phosphate ester monomer, 3 parts of modified nano-SiO2, and 0.3 parts of initiator, the initiator comprises persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, and the preparation steps of the modified polycarboxylic acid grinding aid are as follows: (a) mixing the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate ester monomer at 40°C under nitrogen protection; (b) adding the initiator solution in three stages, adding the persulfate in the first stage, adding the ferrous sulfate in the second stage, and adding the ascorbic acid in the third stage;

[0022] (c) when the conversion rate is ≥80%, adding the modified nano-SiO2, and continuing to react until the viscosity of the system reaches 300 mPa·s.

[0023] In this embodiment, the unsaturated polyether is ethylene glycol monovinyl polyoxyethylene ether, the phosphate ester monomer is methacryloyloxyethyl phosphate, the persulfate is ammonium persulfate, and the modified nano-SiO2 is a product modified by amino silane.

[0024] Example 2: A preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprising the following raw materials by weight: 80 parts of unsaturated polyether, 10 parts of acrylic acid, 11 parts of 2-acrylamide-2-methylpropane sulfonic acid, 3 parts of phosphate ester monomer, 3 parts of modified nano-SiO2, 0.3 parts of initiator, the initiator comprising persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, the preparation steps of the modified polycarboxylic acid grinding aid being as follows: (a) mixing the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate ester monomer under nitrogen protection at 38°C; (b) adding the initiator solution in three stages, adding the persulfate in the first stage, adding the ferrous sulfate in the second stage, and adding the ascorbic acid in the third stage; (c) adding the modified nano-SiO2 when the conversion rate is ≥80%, and continuing to react until the viscosity of the system reaches 280 mPa·s.

[0025] (c) adding the modified nano-SiO2 when the conversion rate is ≥80%, and continuing to react until the viscosity of the system reaches 280 mPa·s.

[0026] In this example, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether and 4-hydroxybutyl vinyl polyoxyethylene ether, the phosphate ester monomer is a mixture of methacryloyloxyethyl phosphate ester and methacryloyloxypropyl phosphate ester, the persulfate is a mixture of ammonium persulfate and potassium persulfate, and the modified nano-SiO2 is a product modified by epoxy silane.

[0027] Example 3: A preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprising the following raw materials by weight: 100 parts of unsaturated polyether, 15 parts of acrylic acid, 13 parts of 2-acrylamide-2-methylpropane sulfonic acid, 7 parts of phosphate ester monomer, 8 parts of modified nano-SiO2, and 0.5 parts of initiator, the initiator comprising persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, the preparation steps of the modified polycarboxylic acid grinding aid being as follows: (a) mixing the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate ester monomer under nitrogen protection at 35°C; (b) adding the initiator solution in three stages, adding the persulfate in the first stage, adding the ferrous sulfate in the second stage, and adding the ascorbic acid in the third stage; (c) adding the modified nano-SiO2 when the conversion rate is ≥80%, and continuing to react until the viscosity of the system reaches 260 mPa·s.

[0028] In this example, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether and isobutylene alcohol polyoxyethylene ether, the phosphate ester monomer is a mixture of methacryloyloxyethyl phosphate ester, methacryloyloxypropyl phosphate ester and 3-methacryloyloxypropyl phosphate ester, the persulfate is a mixture of ammonium persulfate, potassium persulfate and sodium persulfate, and the modified nano-SiO2 is a product modified by methacryloyloxy silane.

[0029] Example 4: A preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprising the following raw materials by weight: 100 parts of unsaturated polyether, 18 parts of acrylic acid, 13 parts of 2-acrylamide-2-methylpropane sulfonic acid, 7 parts of phosphate monomer, 7 parts of modified nano-SiO2, and 0.7 parts of initiator, the initiator comprising persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, the preparation steps of the modified polycarboxylic acid grinding aid being as follows: (a) mixing the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate monomer at 36°C under nitrogen protection; (b) adding the initiator solution in three stages, adding the persulfate in the first stage, adding the ferrous sulfate in the second stage, and adding the ascorbic acid in the third stage;

[0030] (c) when the conversion rate is ≥80%, adding the modified nano-SiO2 and continuing the reaction until the viscosity of the system reaches 250 mPa·s.

[0031] In this example, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether and isobutylene polyoxyethylene ether, the phosphate monomer is a mixture of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate and 3-methacryloyloxypropyl phosphate, the persulfate is a mixture of ammonium persulfate and potassium persulfate, and the modified nano-SiO2 is a product modified by an epoxy silane.

[0032] Example 5: A preparation method of a modified polycarboxylic acid grinding aid, the modified polycarboxylic acid grinding aid comprising the following raw materials by weight: 120 parts of unsaturated polyether, 16 parts of acrylic acid, 10 parts of 2-acrylamide-2-methylpropane sulfonic acid, 6 parts of phosphate monomer, 5 parts of modified nano-SiO2, and 0.6 parts of initiator, the initiator comprising persulfate, ascorbic acid and ferrous sulfate in a molar ratio of 3:1:0.1, the preparation steps of the modified polycarboxylic acid grinding aid being as follows: (a) mixing the unsaturated polyether, the acrylic acid, the 2-acrylamide-2-methylpropane sulfonic acid and the phosphate monomer at 37°C under nitrogen protection; (b) adding the initiator solution in three stages, adding the persulfate in the first stage, adding the ferrous sulfate in the second stage, and adding the ascorbic acid in the third stage;

[0033] (c) when the conversion rate is ≥80%, adding the modified nano-SiO2 and continuing the reaction until the viscosity of the system reaches 240 mPa·s.

[0034] In the embodiment, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, isobutenol polyoxyethylene ether and isoamylenol polyoxyethylene ether, the phosphate monomer is a mixture of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate, 3-methacryloyloxypropyl phosphate and acryloyloxyethyl phosphate, the persulfate is ammonium persulfate, and the modified nano-SiO2 is a product modified by methacryloyloxysilane.

[0035] In the embodiment, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, isobutenol polyoxyethylene ether and isoamylenol polyoxyethylene ether, the phosphate monomer is a mixture of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate, 3-methacryloyloxypropyl phosphate and acryloyloxyethyl phosphate, the persulfate is ammonium persulfate, and the modified nano-SiO2 is a product modified by methacryloyloxysilane.

[0036] (c) When the conversion rate is greater than or equal to 80%, the modified nano-SiO2 is added, and the reaction is continued until the viscosity of the system reaches 280 mPa·s.

[0037] In the embodiment, the unsaturated polyether is a mixture of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, isobutenol polyoxyethylene ether and isoamylenol polyoxyethylene ether, the phosphate monomer is a mixture of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate, 3-methacryloyloxypropyl phosphate and acryloyloxyethyl phosphate, the persulfate is ammonium persulfate, and the modified nano-SiO2 is a product modified by methacryloyloxysilane.

[0038] The performance of the sample of the embodiment of the application is tested according to the method specified in GB / T 26748-2011 Cement Grinding Aids, and the test results are shown in the following table.

[0039]

Claims

1. A method for preparing a modified polycarboxylic acid grinding aid, characterized in that: The modified polycarboxylic acid grinding aid comprises the following raw materials in parts by weight: 80-120 parts of unsaturated polyether, 10-20 parts of acrylic acid, 5-15 parts of 2-acrylamide-2-methylpropanesulfonic acid, 3-8 parts of phosphate monomer, 3-8 parts of modified nano-SiO2, and 0.3-0.7 parts of initiator, wherein the initiator comprises persulfate, ascorbic acid, and ferrous sulfate in a molar ratio of 3:1:0.

1. The preparation steps of the modified polycarboxylic acid grinding aid are as follows: (a) mixing the unsaturated polyether, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and phosphate monomer at 35-40° C. under nitrogen protection; (b) adding the initiator solution dropwise in three stages: persulfate in the first stage, ferrous sulfate in the second stage, and ascorbic acid in the third stage; (c) When the reaction reaches a conversion rate of ≥80%, modified nano-SiO2 is added and the reaction is continued until the viscosity of the system reaches 200-300 mPa·s.

2. The preparation method according to claim 1, wherein: The unsaturated polyether is at least one of ethylene glycol monovinyl polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether, isobutylene alcohol polyoxyethylene ether, and isopentenol polyoxyethylene ether.

3. The preparation method according to claim 1, wherein: The phosphate monomer is one of methacryloyloxyethyl phosphate, methacryloyloxypropyl phosphate, 3-methacryloyloxypropyl phosphate, acryloyloxyethyl phosphate, and 2-acryloyloxyethyl phosphate.

4. The preparation method according to claim 1, wherein: The persulfate is at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

5. The preparation method according to claim 1, wherein: The modified nano-SiO2 is a product modified by one of aminosilane, epoxysilane and methacryloxysilane.

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