阅读说明：本技术 一种聚羧酸减水剂及其制备方法 (Polycarboxylate superplasticizer and preparation method thereof ) 是由 彭湘成 彭国涛 于 2021-05-25 设计创作，主要内容包括：一种聚羧酸减水剂及其制备方法,以烯丙基聚乙二醇和丙烯酸为原料,以3-巯基丙酸作为链转移剂,以特定的双氧水/抗坏血酸/次硫酸氢钠甲醛作为复合引发剂,在具有搅拌功能的四口烧瓶中制得聚羧酸减水剂,相对于现有技术中常用的二元复合引发剂,本发明特定的三元复合引发剂制备而得的聚羧酸减水剂在分散性能以及减水性能等方面都有大幅提升。(A polycarboxylic acid water reducing agent and a preparation method thereof are disclosed, wherein allyl polyethylene glycol and acrylic acid are used as raw materials, 3-mercaptopropionic acid is used as a chain transfer agent, specific hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate is used as a composite initiator, and the polycarboxylic acid water reducing agent is prepared in a four-neck flask with a stirring function.)

1. A preparation method of a polycarboxylate superplasticizer is characterized by comprising the following steps: the method comprises the following steps:

weighing allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43-50 ℃, then dropwise adding a monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator, keeping the temperature for 5-5.5 hours after the dropwise addition is finished, adjusting the pH to be neutral by selecting an alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

2. A method as claimed in claim 1, characterized by: the alkaline solution is sodium carbonate or sodium hydroxide.

3. A method as claimed in claim 1, characterized by: the concentration of the alkaline solution is 20-30 wt%.

4. A method as claimed in claim 1, characterized by: the dosage of the allyl polyethylene glycol-2400 is 5-8 mol.

5. A method as claimed in claim 1, characterized by: the amount of the acrylic acid is 1-1.6 mol.

6. The method of claim 1, wherein the allyl polyethylene glycol-2400 and acrylic acid are present in a 5: 1 molar ratio.

7. The method according to claim 1, wherein the amount of hydrogen peroxide is 0.6-0.8%, the amount of ascorbic acid is 0.1-0.2%, the amount of sodium formaldehyde sulfoxylate is 0.1-0.2%, and the amount of 3-mercaptopropionic acid is 0.4-0.8% with respect to the total mass of acrylic acid and allyl polyethylene glycol-2400.

8. The method according to claim 5, wherein the amount of hydrogen peroxide is 0.8%, the amount of ascorbic acid is 0.13%, the amount of sodium formaldehyde sulfoxylate is 0.16%, and the amount of 3-mercaptopropionic acid is 0.4% with respect to the total mass of acrylic acid and allyl polyethylene glycol-2400.

9. A polycarboxylate water reducer characterized in that it is prepared by the method of any one of claims 1-8.

Technical Field

The invention relates to the field of water reducing agents, and particularly relates to a polycarboxylic acid water reducing agent and a preparation method thereof.

Background

After cement is mixed with water, cement mineral particles have different charges to generate anisotropic attraction or cement particles generate adsorption force due to thermal motion in water to form a flocculent structure, and mixing water is contained in the cement mineral particles to play no role in the fluidity of a mixture and reduce the workability, so that the mixing water quantity is required to be added in construction, the cement hydration consumption is low, and excessive water volatilizes to form more pores after the concrete is hardened, so that the strength and the durability of the concrete are reduced.

The water reducing agent is an additive capable of reducing the mixing water consumption under the condition that the concrete slump is basically the same, most of the water reducing agents are surfactants, and the action effect of the water reducing agent is generated by the surface activity of the surfactant. The molecules of the surfactant material are divided into a hydrophilic end and a hydrophobic end. The hydrophilic end can point to water in water, while the hydrophobic end points to gas, nonpolar liquid or solid substance, so as to reduce interface energy between gas-liquid and liquid-solid, and has functions of wetting, foaming, dispersing and emulsifying. After the water reducing agent is added, the hydrophobic end of the water reducing agent is directionally adsorbed on the surface of the cement mineral particles, and the hydrophilic end faces to the water solution to form an adsorption water film. Because of the directional arrangement of the water reducing agent molecules, the surfaces of the cement particles have the same charges, and under the action of electric repulsion, the cement particles are dispersed, and the flocculent structure is disintegrated into a dispersed structure, so that the wrapped water is released, and the purposes of reducing water and improving fluidity are achieved.

On the market, the water reducing agents are various, and about dozens of types exist, wherein the high-performance polycarboxylic acid water reducing agent is widely applied. In view of the above, how to improve the performance of the polycarboxylate water reducing agent is a subject of long-term research by those skilled in the art.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a polycarboxylate water reducer and a preparation method thereof.

A preparation method of a polycarboxylate superplasticizer comprises the following steps:

weighing allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43-50 ℃, then dropwise adding a monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator, keeping the temperature for 5-5.5 hours after the dropwise addition is finished, adjusting the pH to be neutral by selecting an alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

Further, the alkaline solution is sodium carbonate or sodium hydroxide.

Further, the concentration of the alkaline solution is 20 to 30 wt%.

Further, the dosage of the allyl polyethylene glycol-2400 is 5-8 mol.

Further, the amount of the acrylic acid is 1 to 1.6 mol.

Further, the molar ratio of the allyl polyethylene glycol-2400 to the acrylic acid is 5: 1.

Further, the amount of hydrogen peroxide is 0.6-0.8%, the amount of ascorbic acid is 0.1-0.2%, the amount of sodium formaldehyde sulfoxylate is 0.1-0.2%, and the amount of 3-mercaptopropionic acid is 0.4-0.8% of the total mass of acrylic acid and allyl polyethylene glycol-2400.

Further, the amount of hydrogen peroxide was 0.8%, ascorbic acid was 0.13%, sodium formaldehyde sulfoxylate was 0.16%, and 3-mercaptopropionic acid was 0.4% with respect to the total mass of acrylic acid and allyl polyethylene glycol-2400.

The invention also provides a polycarboxylate superplasticizer prepared by the method.

According to the invention, allyl polyethylene glycol and acrylic acid are used as raw materials, 3-mercaptopropionic acid is used as a chain transfer agent, specific hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate is used as a composite initiator, and a polycarboxylic acid water reducing agent is prepared in a four-neck flask with a stirring function.

Detailed Description

The technical effects of the present invention are demonstrated below by specific examples, but the embodiments of the present invention are not limited thereto.

Example 1

A preparation method of a polycarboxylate superplasticizer comprises the following steps:

weighing 5mol of allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43 ℃, then dropwise adding 1mol of monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium hydrogen sulfite formaldehyde ternary composite initiator, keeping the temperature for 5 hours after the dropwise adding is finished, adjusting the pH to be neutral by selecting a 20 wt% alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

In this example, the amount of hydrogen peroxide used was 0.6%, the amount of ascorbic acid used was 0.1%, the amount of sodium formaldehyde sulfoxylate used was 0.1%, and the amount of 3-mercaptopropionic acid used was 0.4%, relative to the total mass of acrylic acid and allyl polyethylene glycol-2400.

Example 2

A preparation method of a polycarboxylate superplasticizer comprises the following steps:

weighing 5mol of allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43 ℃, then dropwise adding 1mol of monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium hydrogen sulfite formaldehyde ternary composite initiator, keeping the temperature for 5.5 hours after the dropwise adding is finished, adjusting the pH to be neutral by selecting a 20 wt% alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

In this example, the amount of hydrogen peroxide used was 0.6%, the amount of ascorbic acid used was 0.15%, the amount of sodium formaldehyde sulfoxylate used was 0.15%, and the amount of 3-mercaptopropionic acid used was 0.4%, relative to the total mass of acrylic acid and allyl polyethylene glycol-2400.

Example 3

A preparation method of a polycarboxylate superplasticizer comprises the following steps:

weighing 5mol of allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43 ℃, then dropwise adding 1mol of monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium hydrogen sulfite formaldehyde ternary composite initiator, keeping the temperature for 5.5 hours after the dropwise adding is finished, adjusting the pH to be neutral by selecting a 20 wt% alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

In this example, the amount of hydrogen peroxide used was 0.8%, the amount of ascorbic acid used was 0.2%, the amount of sodium formaldehyde sulfoxylate used was 0.2%, and the amount of 3-mercaptopropionic acid used was 0.4%, relative to the total mass of acrylic acid and allyl polyethylene glycol-2400.

Example 4

A preparation method of a polycarboxylate superplasticizer comprises the following steps:

weighing 5mol of allyl polyethylene glycol-2400 according to the weight, adding the allyl polyethylene glycol-2400 into a four-neck flask with a stirring function, adding deionized water, stirring to fully dissolve the allyl polyethylene glycol-2400, raising the temperature to 43 ℃, then dropwise adding 1mol of monomer acrylic acid, a chain transfer agent 3-mercaptopropionic acid and a hydrogen peroxide/ascorbic acid/sodium hydrogen sulfite formaldehyde ternary composite initiator, keeping the temperature for 5.5 hours after the dropwise adding is finished, adjusting the pH to be neutral by selecting a 20 wt% alkaline solution, and cooling to obtain the polycarboxylic acid water reducer.

In this example, the amount of hydrogen peroxide used was 0.8%, the amount of ascorbic acid used was 0.13%, the amount of sodium formaldehyde sulfoxylate used was 0.16%, and the amount of 3-mercaptopropionic acid used was 0.4%, relative to the total mass of acrylic acid and allyl polyethylene glycol-2400.

Comparative example 1

The difference from the embodiment 4 is that the hydrogen peroxide/ascorbic acid binary initiator is used to replace the hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator, and the dosage of the substances is the same as the embodiment 4 except that the sodium formaldehyde sulfoxylate is omitted.

Comparative example 2

The difference from the embodiment 4 is only that the hydrogen peroxide/ascorbic acid binary initiator is used for replacing the hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator, and the dosage of the ascorbic acid is the sum of the dosage of the ascorbic acid and the dosage of the sodium formaldehyde sulfoxylate in the embodiment 4.

Comparative example 3

The difference from the embodiment 4 is that the hydrogen peroxide/sodium formaldehyde sulfoxylate binary initiator is used for replacing the hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator, and the dosage of the substances is the same as that of the embodiment 4 except that the ascorbic acid is omitted.

Comparative example 4

The difference from the embodiment 4 is only that the hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator is replaced by the hydrogen peroxide/sodium formaldehyde sulfoxylate binary initiator, and the dosage of the sodium formaldehyde sulfoxylate is the sum of the dosages of the ascorbic acid and the sodium formaldehyde sulfoxylate in the embodiment 4.

Further, the inventors evaluated the polycarboxylate water reducing agent performance by the cement paste fluidity and the water reducing rate. Wherein, the fluidity of the cement paste is determined according to GB/T8077-2012, the W/C is 0.29, and the folding and solid content of the water reducing agent is 0.2 percent of the mass of the cement; the water reducing rate is determined according to the GB8076-2008 standard, the W/C is 0.29, the folding and fixing mixing amount of the water reducing agent is 0.2 percent of the mass of the cement, the testing temperature is 25 ℃, and the experimental cement is produced by Anhui conch cement company Limited.

The experimental data for examples 1-4 and comparative examples 1-4 are shown in table 1.

TABLE 1 Experimental data for examples and comparative examples

As can be seen from Table 1, the specific hydrogen peroxide/ascorbic acid/sodium formaldehyde sulfoxylate ternary composite initiator can greatly improve the dispersing property and the water reducing property of the polycarboxylic acid water reducer.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.