CN101531480B - Polycarboxylate cement dispersant and preparation method thereof - Google Patents

Abstract

The invention relates to a polycarboxylate cement dispersant and a preparation method thereof, belonging to the technical field of building materials. The invention is characterized by providing the technical proposal of a dispersant which changes the traditional polyether type polycarboxylic acid structure, improves the initial net paste fluidity of the cement and reduces bleeding by adding a monomer, namely, N-glycine base maleichydrazide amino acid, into a concrete additive, and a preparation method thereof. The synthesis technique of the novel polycarboxylic acid dispersant which takes the N-glycine base maleichydrazide amino acid, allyl-polyethlene glycol, acrylamide, and methacrylic sodium allysulfonate as raw materials is simple and green; the initial net paste fluidity of the cement is good and bleeding does not happen; the dispersant has little doping amount in the cement and occupies 0.18 to 0.6 percent of the total weight of the cement after solidification, thus improving cement strength and meeting higher construction requirement.

Description

A kind of polycarboxylate cement dispersant and preparation method thereof

technical field

The invention relates to a polycarboxylate cement dispersant and a preparation method thereof, which belong to the technical field of building materials, and specifically relate to a concrete admixture that changes the traditional polyether type by adding a monomer N-glycine-based maleimic acid The invention discloses a polycarboxylic acid structure, a dispersant for improving the initial fluidity of cement paste and reducing bleeding, and a technical proposal for a preparation method thereof.

Background technique

Concrete admixture is one of the indispensable components of modern concrete. Adding an appropriate amount of dispersant in concrete can significantly improve the working performance of fresh concrete and the comprehensive performance of hardened concrete. Dispersant is currently the most widely studied and used concrete admixture.

The development of cement dispersant (also known as water reducer) has a long history. In 1935, E.W. Scripcher of the United States first developed a plasticizer with lignosulfonate as the main component, which was widely used in C20-C40 concrete, promoting the development of concrete to medium strength; in 1962, Japan successfully developed naphthalene sulfonate Acid-formaldehyde condensate high-efficiency water reducer, this type of water reducer has the advantages of low production cost and good water reduction effect, so it is widely used in C30~C60 concrete, promoting the development of concrete to high strength. However, the slump loss of the concrete prepared by using the water reducing agent is fast, which cannot meet the construction requirements such as pumping, and cannot be used to prepare high-performance concrete.

As a new generation of products, polycarboxylate dispersants have unique advantages such as low dosage, high water reducing rate, no retardation, low slump loss, and environmental protection. It is suitable for ordinary concrete and special concrete such as high-strength, self-compacting and fair-faced concrete.

CN00103594.0 reports a preparation method of a polyester-type polycarboxylic acid-based high-performance dispersant, which uses a large amount of organic solvents that are not conducive to environmental protection and is not conducive to clean production in the production process.

CN1847187A has reported a kind of preparation method of polyether type polycarboxylic acid series dispersant, and this dispersant adds the water-cement ratio and is the cement of 0.29 initial slurry fluidity bad, bleeding phenomenon is serious, and complexability is bad, This limits the use of such dispersants in some occasions.

Contents of the invention

A kind of polycarboxylate cement dispersant of the present invention and the purpose of preparation method thereof are: overcome the shortcoming and deficiency that exist in the above-mentioned prior art, thereby provide a kind of environmental protection concrete admixture by adding a kind of monomer N-glycine A dispersant for changing the traditional polyether-type polycarboxylic acid structure, improving the fluidity of the initial cement slurry and reducing bleeding, and a technical solution for its preparation method based on maleimic acid.

A polycarboxylate cement dispersant of the present invention is characterized in that it is a kind of by adding a kind of monomer N-glycine-based maleimic acid to change the structure of traditional polyether type polycarboxylic acid and improve the fluidity of cement initial slurry and a dispersant for reducing bleeding, wherein the structure of the N-glycine-based maleimic acid monomer is:

, The dispersant is a light yellow transparent liquid with a concentration of 10% to 45% and no irritating odor.

The preparation method of the above-mentioned polycarboxylate cement dispersant is characterized in that it is a method of changing the structure of traditional polyether-type polycarboxylic acid by adding a monomer N-glycine-based maleimic acid, and improving the initial cleaning of cement. The preparation method of the dispersant for reducing fluidity and bleeding, the mole fraction of the dispersant monomer is: 20-50 parts of N-glycine-based maleimide, 15-43 parts of allyl polyethylene glycol , 33-90 parts of acrylamide, 10 parts of sodium methacrylate, 4.1-5.2 parts of potassium persulfate, 3300-19300 parts of deionized water; the molecular weight of allyl polyethylene glycol is 700, 1000 or 2000; N -The optimal range of glycine-based maleyl acid is 20 to 50 parts; the optimal range of acrylamide is 33 to 90 parts, and the specific steps are:

I. Mix 20-50 parts of N-glycine-based maleamic acid and 15-43 parts of allyl polyethylene glycol to form an aqueous solution, which is used as a reaction base material, and added to a stirred reactor, and heated to 70～85℃;

II. Mix 33-90 parts of acrylamide and 10 parts of sodium methacrylate to prepare an aqueous solution;

III, potassium persulfate and deionized water are made into 5% aqueous solution;

IV. Add the aqueous solution of step II and step III dropwise into the base material in step I respectively, and the dropping time is controlled at 30-60 minutes, then maintain the reaction temperature and continue the reaction for 30-60 minutes to obtain polycarboxylic acid;

V. Cool the polycarboxylate prepared in the above step IV to below 40° C., and neutralize it with 20-30% sodium hydroxide to a pH of 6.5-7.5 to obtain a polycarboxylate cement dispersant.

The advantage of a kind of polycarboxylate cement dispersant of the present invention and preparation method thereof is: be raw material with N-glycine base maleamic acid, allyl polyethylene glycol, acrylamide, sodium methacryl sulfonate The synthesis process of the new polycarboxylic acid dispersant is simple, green, and the initial cement slurry has good fluidity and no bleeding; the present invention combines N-glycine-based maleimic acid and allyl polyethylene glycol by changing the polymerization process. Glycol is added in the reactor together as reaction bottom material, and polymerization reaction is more uniform; The dispersant of the present invention is mixed in the concrete with little amount, generally 0.18%～0.6% of the total weight of cement after being folded and solidified, so that it has good Excellent initial cement slurry fluidity, good compounding performance, can improve concrete strength and meet higher construction requirements.

Detailed ways

In order to better understand the present invention, the content of the present invention will be further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

The unit selected in the embodiment is mole fraction

Implementation mode 1:

Take the best ratio

Mix 30 parts of N-glycylmaleimic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and then prepare 33 parts of acrylamide The mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 4.4 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, and controlled at 30 to 60 minutes. Afterwards, the reaction temperature was maintained to continue the reaction for 60 min, and 30% sodium hydroxide solution was added to adjust the pH value to 7. Adding 0.2% of the dispersant to the weight of the cement after folding and solidification can make the initial fluidity of the cement slurry with a water-cement ratio of 0.29 265mm, 267mm in 1h, and 270mm in 2h.

Implementation mode 2:

Mix 30 parts of N-glycylmaleimic acid and 43 parts of allyl polyethylene glycol with a molecular weight of 700 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and then prepare 33 parts of acrylamide The mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 4.4 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, and controlled at 30 to 60 minutes. Afterwards, maintain the reaction temperature and continue to react for 60 minutes, add 30% sodium hydroxide solution, adjust the pH value to 7, and add 0.2% of the dispersant accounting for cement weight after folding, so that the cement paste with a water-cement ratio of 0.29 can be initially Fluidity is 230mm, 1h clean pulp fluidity is 235mm, 2h clean pulp fluidity is 230mm.

Implementation mode 3:

Mix 30 parts of N-glycylmaleimic acid and 30 parts of allyl polyethylene glycol with a molecular weight of 1000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and prepare 33 parts of acrylamide The mixed aqueous solution of mol and 10 parts of sodium methacryl sulfonate and 4.4 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 to 60 minutes. Afterwards, maintain the reaction temperature and continue to react for 60 minutes, add 30% sodium hydroxide solution, adjust the pH value to 7, and add 0.2% of the dispersant accounting for cement weight after folding, so that the cement paste with a water-cement ratio of 0.29 can be initially Fluidity is 240mm, 1h clean pulp fluidity is 240mm, 2h clean pulp fluidity is 245mm.

Implementation mode 4:

Mix 50 parts of N-glycine-based maleamic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and prepare 33 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 5.2 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, after that, the reaction temperature was maintained for 60 minutes, and 30% hydrogen was added Sodium oxide solution, adjust the pH value to 7, after folding and solidifying, add the dispersant accounting for 0.2% of the cement weight, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 245mm, and the fluidity of the 1h clean paste is 250mm. 2h clean slurry fluidity is 255mm.

Implementation mode 5:

Mix 50 parts of N-glycylmaleimic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and then prepare 90 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 5.2 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, after that, the reaction temperature was maintained for 60 minutes, and 30% hydrogen was added Sodium oxide solution, adjust the PH value to 7, and add the dispersant accounting for 0.2% of the cement weight after folding, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 230mm, and the fluidity of the 1h clean paste is 235mm. The fluidity of the 2h net pulp is 237mm.

Implementation mode 6:

Mix 50 parts of N-glycine-based maleamic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and prepare 33 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 4.8 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, after that, the reaction temperature was maintained for 60 minutes, and 30% hydrogen was added Sodium oxide solution, adjust the pH value to 6.5, and add 0.2% of the dispersant accounting for cement weight after solidification, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 225mm, and the fluidity of the cement slurry is 230mm in 1h. The fluidity of the net pulp is 240mm.

Implementation mode 7:

Mix 20 parts of N-glycine-based maleamic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and prepare 33 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacrylsulfonate and 4.1 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, and then maintained at the reaction temperature for 60 minutes, adding 30% hydrogen Sodium oxide solution, adjust the PH value to 7, and add the dispersant accounting for 0.2% of the cement weight after folding, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 240mm, and the fluidity of the 1h clean paste is 240mm. The fluidity of the 2h net pulp is 245mm.

Implementation mode 8:

Mix 20 parts of N-glycylmaleimic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and then prepare 90 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 4.4 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, and then the reaction temperature was maintained for 60 minutes, and 30% hydrogen was added Sodium oxide solution, adjust the pH value to 7.5, and add 0.2% of the dispersant accounting for the weight of cement after folding, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 230mm, and the fluidity of the 1h clean paste is 235mm. The fluidity of the 2h net pulp is 235mm.

Implementation mode 9:

Mix 20 parts of N-glycylmaleimic acid and 15 parts of allyl polyethylene glycol with a molecular weight of 2000 to form an aqueous solution, add it to a stirred reactor, heat up to 80°C, and prepare 75 parts of acrylamide Mixed aqueous solution of 10 parts of sodium methacryl sulfonate and 4.4 parts of 5% potassium persulfate aqueous solution were added dropwise with a constant pressure dropping funnel, controlled at 30 minutes, and then the reaction temperature was maintained for 60 minutes, and 30% hydrogen was added Sodium oxide solution, adjust the pH value to 7, after folding and solidifying, add the dispersant accounting for 0.2% of the cement weight, so that the initial fluidity of the cement paste with a water-cement ratio of 0.29 is 245mm, and the fluidity of the 1h clean paste is 250mm. 2h clean slurry fluidity is 255mm.

Claims (1)

1. a preparation method of polycarboxylate cement dispersant, it is characterized in that a kind of by adding a kind of monomer N-glycine base maleamic acid to change traditional polyether type polycarboxylic acid structure, improve cement initial cleanness A method for preparing a dispersant for slurry fluidity and reducing bleeding. The mole fraction of the dispersant monomer is: 20-50 parts of N-glycine-based maleamic acid, 15-50 parts of allyl polyethylene glycol 43 parts, 33-90 parts of acrylamide, 10 parts of sodium methacrylate, 4.1-5.2 parts of potassium persulfate, 3300-19300 parts of deionized water; the molecular weight of allyl polyethylene glycol is 700, 1000 or 2000 The optimal range of N-glycine-based maleyl acid is 20 to 50 parts; the optimal range of acrylamide is 33 to 90 parts, and the specific steps are: I. Mix 20-50 parts of N-glycine-based maleamic acid and 15-43 parts of allyl polyethylene glycol to form an aqueous solution, which is used as a reaction base material, and added to a stirred reactor, and heated to 70～85℃; II. Mix 33-90 parts of acrylamide and 10 parts of sodium methacrylate to prepare an aqueous solution; III, potassium persulfate and deionized water are made into 5% aqueous solution; IV. Add the aqueous solution of step II and step III dropwise into the base material in step I respectively, and the dropping time is controlled at 30-60 minutes, then maintain the reaction temperature and continue the reaction for 30-60 minutes to obtain polycarboxylic acid; V. The polycarboxylic acid prepared in the above step IV is cooled to below 40°C, and neutralized to a pH of 6.5 to 7.5 with 20 to 30% sodium hydroxide to obtain a monomer N-glycine base Lycine is a dispersant that changes the structure of traditional polyether-type polycarboxylic acid, improves the fluidity of cement initial paste and reduces bleeding. The structure of N-glycine-based maleamic acid monomer is:

The dispersant is a light yellow transparent liquid with a concentration of 10% to 45% and no irritating smell.