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 田明 钟康 贺任 谭亮 颜文海 于 2020-12-21 设计创作，主要内容包括：本发明提供了一种聚羧酸减水剂及其制备方法,以解决现有的减水剂易受混凝土含泥量影响的问题。本发明的聚羧酸减水剂,制备原料含有单6-甲基丙烯酸缩水甘油酯-乙醇胺-β-环糊精、乙二醇单乙烯基聚乙二醇醚、丙烯酸、氧化剂、还原剂、链转移剂、第一pH调节剂和水。本发明的聚羧酸减水剂,使用过程中,不易受混凝土含泥量的影响,该减水剂以氧化还原体系为引发体系,制备时,通过滴加速度控制反应速度,可实现常温无需控温的聚合反应工艺,可节约能源与成本。(The invention provides a polycarboxylate superplasticizer and a preparation method thereof, aiming at solving the problem that the existing superplasticizer is easily influenced by the mud content of concrete. The preparation raw materials of the polycarboxylic acid water reducing agent comprise mono-6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin, ethylene glycol monovinyl polyglycol ether, acrylic acid, an oxidizing agent, a reducing agent, a chain transfer agent, a first pH regulator and water. The polycarboxylate superplasticizer is not easily influenced by the mud content of concrete in the using process, takes a redox system as an initiating system, controls the reaction speed through the dropping speed during preparation, can realize a polymerization reaction process at normal temperature without temperature control, and can save energy and cost.)

1. The polycarboxylate superplasticizer is characterized by comprising the following preparation raw materials:

the water-soluble polymer comprises 6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin, ethylene glycol monovinyl polyglycol ether, acrylic acid, an oxidizing agent, a reducing agent, a chain transfer agent, a first pH regulator and water.

2. The polycarboxylate water reducer according to claim 1, which is prepared from the following raw materials in parts by weight:

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 2 to 10 parts by weight of a stabilizer,

ethylene glycol monovinyl polyglycol ether: 10 to 40 parts of (A) a water-soluble polymer,

acrylic acid: 3 to 5 parts of (A) a water-soluble polymer,

oxidizing agent: 0.1 to 0.5 part by weight,

reducing agent: 0.1 to 0.5 part by weight,

chain transfer agent: 0.1 to 0.3 part by weight,

first pH adjuster: 6 to 7 parts of (A) a water-soluble polymer,

water: 30-40 parts.

3. The polycarboxylate water reducer according to claim 1 or 2, characterized in that the raw materials for preparing the mono-6-glycidyl methacrylate-ethanolamine- β -cyclodextrin are as follows: beta-cyclodextrin, p-methoxybenzenesulfonic acid chloride, organic amine, glycidyl methacrylate, alkali, acetone, N-dimethylformamide, benzenediol, a second pH regulator and water.

4. The polycarboxylate water reducer according to claim 3, characterized in that the organic amine is ethanolamine.

5. The polycarboxylate water reducer according to claim 3, characterized in that the second pH regulator is hydrochloric acid with a mass fraction of less than 20%.

6. The polycarboxylate water reducer according to claim 1 or 2, characterized in that the oxidant is at least one selected from hydrogen peroxide, potassium peroxide and sodium peroxide sulfate.

7. The polycarboxylate water reducer according to claim 1 or 2, characterized in that the reducing agent is selected from at least one of ferrous sulfate and L-ascorbic acid.

8. The polycarboxylate water reducer according to claim 1 or 2, wherein said chain transfer agent is at least one selected from thioglycolic acid and mercaptopropionic acid.

9. The polycarboxylate water reducer according to claim 1 or 2, characterized in that the first pH regulator is selected from at least one of sodium hydroxide and potassium hydroxide.

10. A method for preparing a polycarboxylic acid water reducer according to any one of claims 1 to 9, characterized by comprising the steps of:

s1: adding the mono-6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin and an oxidant into part of water to obtain a bottom material;

s2: dissolving the acrylic acid in part of water to obtain a material A;

s3: dissolving the ethylene glycol monovinyl polyethylene glycol ether in part of water to obtain a material B;

s4: adding a reducing agent and a chain transfer agent into part of water to obtain a material C;

s5: and (3) simultaneously dripping the material A, the material B and the material C into the base material for reaction, and then adding the first pH regulator and the residual water to obtain the polycarboxylate superplasticizer.

Technical Field

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

Background

With the rapid development of the capital construction industry, the demand of concrete is increased dramatically, thereby accelerating the development of concrete admixtures. In the concrete admixture, the influence of the water reducing agent on the concrete is very important. The performance of the water reducing agent directly influences the transportation, pumping, construction and later strength of concrete. The polycarboxylate superplasticizer serving as a third-generation water reducer has the advantages of high water reducing rate, good slump retention, low shrinkage, strong designability of molecular structure, environmental friendliness and the like compared with the first two-generation water reducers, namely lignosulfonate water reducers and Chua water reducers, and is widely applied to concrete.

However, clays such as montmorillonite, kaolin, and smectite in concrete are adsorptive to polycarboxylic acid water reducing agents, particularly montmorillonite, whose structure is such that each crystal layer is composed of two silica tetrahedrons sandwiching an octahedron of alumina, the layers are connected by van der waals' force between oxygen atoms, the force is weak, and the distance between layers is large, so that water in the system is easily adsorbed into the layers to form hydrogen bonds with the oxygen atoms between the layers. And oxygen atoms in the oxyethylene groups of the polyether side chains of the polycarboxylic acid water reducing agent can form hydrogen bonds with interlayer water, so that long side chains of the polycarboxylic acid water reducing agent are adsorbed into interlayer of montmorillonite. In addition, hydrated sodium ions exist among montmorillonite layers, and the ethoxyalkenyl in the polyether side chain in the polycarboxylate superplasticizer is easy to complex with the sodium ions, so that the oxyethylene side chain enters among silica layers of the sodium-based montmorillonite. And isomorphous replacement exists in the montmorillonite crystal unit cells, so that permanent negative charges appear in the clay crystal layer, the end face of the crystal layer is easy to adsorb cations, mainly calcium ions in cement, and carboxyl of the polycarboxylic acid water reducing agent is easy to complex with the calcium ions to form an integral compound to be adsorbed. Thus, the polycarboxylate water reducer has a significantly compromised, or even failed, performance in cementitious concrete applications.

At present, the exploitation amount of the raw material sandstone of the concrete is large, the resource of high-quality sandstone is in short supply, and the sand containing the silt is often used in the engineering. A large amount of sand with high mud content is directly used in concrete, which can affect the performance of the polycarboxylic acid water reducing agent. In the prior art, in order to solve the influence of clay on the water reducing agent, the first method is to wash sand and stone, but the washing of sand and stone takes time and labor, and can influence the gradation of sand and stone, thereby influencing the performance of concrete, and the cost is higher; the second method is to increase the amount of water reducing agent, but over-blending can cause bleeding and segregation of the concrete. Therefore, there is still a need to develop a water reducing agent which is not affected by the mud content of concrete.

Disclosure of Invention

The present invention is directed to solving at least one of the above problems in the prior art. Therefore, the invention provides a polycarboxylate superplasticizer and a preparation method thereof, and aims to solve the problem that the existing superplasticizer is easily influenced by the mud content of concrete.

The invention provides a polycarboxylate superplasticizer in a first aspect, which comprises the following preparation raw materials:

the water-soluble polymer comprises 6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin, ethylene glycol monovinyl polyglycol ether, acrylic acid, an oxidizing agent, a reducing agent, a chain transfer agent, a first pH regulator and water.

According to one embodiment of the invention, the polycarboxylate superplasticizer is prepared from the following raw materials in parts by weight:

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 2 to 10 parts by weight of a stabilizer,

ethylene glycol monovinyl polyglycol ether: 10 to 40 parts of (A) a water-soluble polymer,

acrylic acid: 6 to 8 parts of (A) a water-soluble polymer,

oxidizing agent: 1.0 to 2.0 parts by weight,

reducing agent: 0.05 to 0.07 part by weight,

chain transfer agent: 0.2 to 0.4 part by weight,

first pH adjuster: 1.0 to 2.0 parts by weight,

water: 40-45 parts.

According to one embodiment of the present invention, the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide, potassium peroxide sulfate, and sodium peroxide sulfate.

According to one embodiment of the invention, the reducing agent is selected from at least one of ferrous sulfate, L-ascorbic acid, E-51.

According to an embodiment of the present invention, the chain transfer agent is at least one selected from thioglycolic acid and mercaptopropionic acid, and the chain transfer is completed while a carboxyl functional group is introduced to increase the adsorptivity of the chain transfer agent.

Can agglomerate to increase the adsorptivity of the water reducing agent to cement.

According to one embodiment of the present invention, the first pH adjusting agent is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.

According to one embodiment of the invention, the raw material for preparing the mono-6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin comprises the following components in parts by weight: 20-30 parts of beta-cyclodextrin, 8-12 parts of p-methoxybenzenesulfonic acid chloride, 50-60 parts of organic amine, 2-4 parts of glycidyl methacrylate, 6-7 parts of alkali, 10-20 parts of acetone, 10-20 parts of N-dimethylformamide, 0.01-0.05 part of benzenediol, 0.5-1 part of a second pH regulator and 10-20 parts of water.

According to an embodiment of the present invention, the method for preparing the mono-6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin comprises: dissolving beta-cyclodextrin in water to obtain a beta-cyclodextrin suspension, and sequentially adding alkali, p-methoxybenzenesulfonic acid chloride, N-dimethylformamide, organic amine, benzenediol, a second pH regulator, glycidyl methacrylate and acetone while stirring.

According to one embodiment of the invention, the base is sodium hydroxide.

According to one embodiment of the invention, the organic amine is ethanolamine.

According to an embodiment of the present invention, the second pH adjusting agent is hydrochloric acid with a mass fraction of less than 20%.

The second aspect of the invention provides a method for preparing the polycarboxylic acid water reducing agent, which comprises the following steps:

s1: adding the mono-6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin and an oxidant into part of water to obtain a bottom material;

s2: dissolving the acrylic acid in part of water to obtain a material A;

s3: dissolving the ethylene glycol monovinyl polyethylene glycol ether in part of water to obtain a material B;

s4: adding a reducing agent and a chain transfer agent into part of water to obtain a material C;

s5: and (3) simultaneously dripping the material A, the material B and the material C into the base material for reaction, and then adding the first pH regulator and the residual water to obtain the polycarboxylate superplasticizer.

The polycarboxylic acid water reducing agent disclosed by the invention at least has the following technical effects:

the ethylene glycol monovinyl polyglycol ether is used, wherein the ethylene glycol monovinyl polyglycol ether has a vinyl group directly connected with an oxygen atom and has no substituent, so that the vinyl group has high activity, can obtain high conversion rate and proper molecular weight in a low-temperature initiated reduction system, has larger diameter with the oxygen atom than a carbon atom, has larger freedom of movement of a polyether side chain connected with the oxygen atom, and can reduce the adsorption of clay to the polyether side chain, thereby increasing the adaptability of the polycarboxylic acid water reducing agent to clay.

According to the polycarboxylate water reducer disclosed by the invention, the beta-cyclodextrin monomer is introduced into the side chain, the space structure of the beta-cyclodextrin is a hollow cylindrical structure, the steric hindrance effect is remarkable, the rigidity of the beta-cyclodextrin side chain is stronger than that of a polyoxyethylene side chain, and the absorption of the side chain and carboxyl of the water reducer by montmorillonite can be effectively prevented.

The beta-cyclodextrin is connected with the main chain of the polycarboxylate water reducer through an ester group, and because a concrete system is alkaline, the ester group is hydrolyzed under the alkaline condition to generate beta-cyclodextrin micromolecules, and the hydroxyl of the beta-cyclodextrin is dehydrogenated under the alkaline condition to generate anions. Therefore, the beta-cyclodextrin can be adsorbed to the surface of the montmorillonite in an electrostatic attraction manner, so that the carboxyl in the polycarboxylate water reducer is effectively prevented from being adsorbed by the montmorillonite, and the adverse effect of the montmorillonite on the polycarboxylate water reducer is inhibited.

The polycarboxylate superplasticizer takes an oxidation reduction system as an initiating system, and when in preparation, the reaction speed is controlled by the dropping speed, so that a polymerization reaction process without temperature control at normal temperature can be realized, and energy and cost can be saved.

Detailed Description

The following are specific examples of the present invention, and the technical solutions of the present invention will be further described with reference to the examples, but the present invention is not limited to the examples.

Preparation method of water reducing agent

The embodiment provides a method for preparing a polycarboxylate superplasticizer, which comprises the following specific steps:

s1: adding single 6-glycidyl methacrylate-ethanolamine-beta-cyclodextrin and an oxidant into part of water to obtain a bottom material;

s2: mixing acrylic acid

Dissolving in partial water to obtain material A;

s3: dissolving ethylene glycol monovinyl polyglycol ether in partial water to obtain a material B;

s4: adding a reducing agent and a chain transfer agent into part of water to obtain a material C;

s5: and (3) simultaneously dripping the material A, the material B and the material C into the base material for reaction, and then adding a first pH regulator and the residual water to obtain the polycarboxylate superplasticizer.

The first pH regulator is at least one of sodium hydroxide and potassium hydroxide.

Example 1

In this embodiment, referring to the preparation method of the water reducing agent, a polycarboxylic acid water reducing agent is prepared, which includes:

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 20g of

Ethylene glycol monovinyl polyglycol ether: 180g

Acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

Example 2

In this embodiment, referring to the preparation method of the water reducing agent, a polycarboxylic acid water reducing agent is prepared, which includes:

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 10g of a mixture of the above-mentioned components,

ethylene glycol monovinyl polyglycol ether: 190g of the total weight of the powder,

acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide solution: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

Comparative example 1

The comparative example refers to a preparation method of a water reducing agent, and prepares a polycarboxylic acid water reducing agent, which comprises:

ethylene glycol monovinyl polyglycol ether: 200g of the total weight of the mixture,

acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide solution: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

Comparative example 2

The comparative example refers to a preparation method of a water reducing agent, and prepares a polycarboxylic acid water reducing agent, which comprises:

molecular weight 3000 isopentenyl polyglycol ether: 180g of the total weight of the mixture,

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 20g of

Acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide solution: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

Comparative example 3

The comparative example refers to a preparation method of a water reducing agent, and prepares a polycarboxylic acid water reducing agent, which comprises:

polyethylene glycol ether with molecular weight of 6000 monovinyl glycol: 180g of the total weight of the mixture,

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 20g of

Acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide solution: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

Comparative example 4

The comparative example refers to a preparation method of a water reducing agent, and prepares a polycarboxylic acid water reducing agent, which comprises:

polyethylene glycol monoethyl ether having a molecular weight of 1200 monovinyl glycol: 180g of the total weight of the mixture,

mono 6-glycidyl methacrylate-ethanolamine- β -cyclodextrin: 20g of

Acrylic acid: the weight of the mixture is 32g,

30% hydrogen peroxide solution: 6.76g of a mixture of (A) and (B),

vitamin C: 0.3g of a mineral oil in the form of a mineral oil,

mercaptopropionic acid: 1.5g of a mixture of (A) and (B),

30% sodium hydroxide solution: 6g of the total weight of the mixture is obtained,

deionized water: 200 g.

The suppliers and the brands of the relevant materials are shown in table 1.

TABLE 1

Raw material	Suppliers of goods	Number plate
			Ethylene glycol monovinyl polyglycol ether	LIAONING OXIRANCHEM Co.,Ltd.	609-3
Isopentenyl polyglycol ether	LIAONING OXIRANCHEM Co.,Ltd.	609
			Acrylic acid	Aladdin	Analytical purity
Vitamin C	Aladdin	Analytical purity

Example of detection

The water reducing agents prepared in examples 1 and 2 and comparative examples 1 to 4 were tested for their flexural and net slurry fluidity at different montmorillonite loadings, and the results are shown in table 2.

TABLE 2

The cement used in the detection is P.O42.5 of Taojiang, in the detection, the ratio of the cement to water is 300:82, in the experiment of doping clay, the clay replaces part of the cement mass, the gradient test is carried out by respectively replacing 0%, 2% and 4% of the cement with the clay, and the montmorillonite is K-10 montmorillonite of the Aladdin. The synthesized water reducer mother liquor contains 7% of water reducer at the beginning of dilution, in a performance test, the mixing amount of the 7% water reducer is 1.6%, the addition amount converted into the solid content is 0.11%, and the mixing amount is calculated on the basis of the mass of cement.

The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments described above, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.