CN112876619A

CN112876619A - Anti-mud polycarboxylate superplasticizer and preparation method thereof

Info

Publication number: CN112876619A
Application number: CN202110159933.5A
Authority: CN
Inventors: 屈浩杰; 钱珊珊; 彭荩影; 赵旭; 王学川; 郑春扬
Original assignee: Jiangsu China Railway ARIT New Materials Co Ltd
Current assignee: Jiangsu China Railway ARIT New Materials Co Ltd
Priority date: 2021-02-05
Filing date: 2021-02-05
Publication date: 2021-06-01

Abstract

The invention discloses an anti-mud polycarboxylic acid water reducing agent and a preparation method thereof, wherein the preparation method comprises the following steps: and carrying out free radical polymerization reaction on the unsaturated small monomer B, the unsaturated macromonomer and the cucurbituril macromonomer to prepare the polycarboxylic acid water reducing agent with cucurbituril as a grafting side chain in a molecular structure. The obtained polymeric product contains a melon ring structure with large physical size and internal hydrophobicity and external hydrophilicity, the melon ring is introduced on the basis of the original comb structure, and compared with the conventional polycarboxylic acid water reducing agent, the steric hindrance of the water reducing agent can be increased, the insertion of the side chain of the polyether macromonomer between montmorillonite layers due to the hydrogen bond effect is slowed down, the adsorption effect of the polycarboxylic acid water reducing agent on montmorillonite is reduced, and the ineffective consumption of the water reducing agent is reduced. The problem of the existing polycarboxylic acid water reducing agent in the clay tolerance is solved, the dosage of the water reducing agent is reduced, and the effectiveness of the water reducing agent is greatly improved.

Description

Anti-mud polycarboxylate superplasticizer and preparation method thereof

Technical Field

The invention relates to the technical field of polycarboxylate superplasticizers, and particularly relates to an anti-mud polycarboxylate superplasticizer and a preparation method thereof.

Background

The polycarboxylate superplasticizer is a third-generation superplasticizer behind a wood sulfonic acid water-reducing agent and a naphthalene water-reducing agent, mainly disperses cement particles through steric hindrance and electrostatic resistance, can prevent concrete slump loss without causing obvious retardation, exerts a higher plasticizing effect under low mixing amount, has good fluidity retentivity, and reduces unit water consumption. The method is widely applied to projects such as highways, bridges, dams, tunnels, high-rise buildings and the like. The product is green and environment-friendly, is not flammable and explosive, and can be safely transported by trains and automobiles.

The polycarboxylate superplasticizer has good application effect, but because the cement contains clay (such as montmorillonite, illite, kaolin and the like), the added polycarboxylate superplasticizer can react with the cement, so that the adsorption capacity between the clay and the polycarboxylate superplasticizer is tens of times or more of that of the polycarboxylate superplasticizer and the cement, the invalid consumption of the polycarboxylate superplasticizer is caused, and the capability of dispersing cement particles is reduced to a great extent. Related researches show that montmorillonite has the biggest adverse effect on the water reducing agent in a plurality of clays. The structure of montmorillonite is: the middle of the clay mineral is provided with an aluminum oxygen octahedron, and the upper part and the lower part of the clay mineral are provided with three layers of sheet structures consisting of silicon oxygen tetrahedrons, and researchers introduce cyclodextrin serving as a grafting side chain into a polycarboxylate water reducer, so that ineffective adsorption of montmorillonite and the water reducer can be effectively reduced, but the synthesis process is troublesome, the environmental pollution is serious, and a polycarboxylate water reducer with cucurbituril as the grafting side chain is not reported. Cucurbituril is also called cucurbituril, is a new class of large-ring main body molecules following cyclodextrin, has a symmetrical cucurbituril structure, is suitable for inclusion of molecules, and has high thermal stability and chemical stability, carbonyl oxygen atoms with the same number as the cucurbituril monomers are distributed at two ends of the cucurbituril respectively, and the carbonyl oxygen atoms have hydrophilicity, so that the cucurbituril can easily interact with hydrophilic substances, metal ions and the like, and can contain hydrophobic organic molecules or hydrophobic parts of molecules by using hydrophobic cavities, and therefore, the water reducing agent grafted with the cucurbituril has good economic, social and environmental benefits.

Disclosure of Invention

1. The technical problem to be solved is as follows:

aiming at the technical problems, the invention provides the anti-mud polycarboxylate water reducer and the preparation method thereof.

2. The technical scheme is as follows:

the mud-resistant polycarboxylate superplasticizer is characterized by comprising the following components in parts by weight: reacting the unsaturated small monomer A, butylammonium and cucurbituril to prepare cucurbituril macromonomer, and carrying out free radical polymerization reaction on the unsaturated small monomer B, the unsaturated macromonomer and the cucurbituril macromonomer to prepare a polycarboxylic acid water reducing agent with cucurbituril as a grafted side chain in a molecular structure; the structural formula of the prepared polycarboxylic acid water reducing agent is specifically as follows:

in the formula, the polymerization degree a is an integer of 1-5000; the polymerization degree b is an integer of 1-5000; the polymerization degree x is an integer of 0-200; the number n of the repeating units is an integer of 1 to 200; r₁is-H or-CH₃or-COOH; r₂is-H or-CH₃；R₃is-H or-CH₃；R₄is-CH₂-or-CH₂-CH₂-or-C ═ O-; the ring structure in the above formula represents cucurbituril.

Further, the unsaturated small monomer A is one or two of methacrylic acid and acrylic acid.

Further, the cucurbituril is one or a combination of methacrylic acid and acrylic acid.

Further, the unsaturated small monomer B is one or a combination of two or more of methacrylic acid, acrylic acid and maleic anhydride.

Further, a chain transfer agent is also included in the free radical polymerization reaction; the chain transfer agent is one or the combination of two or more of sodium methyl propylene sulfonate, mercaptoethanol, mercaptopropionic acid and sodium hypophosphite.

Further, an initiator is also included in the free radical polymerization reaction; the initiator is one or the combination of two or more of ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide or azodiisobutyronitrile.

Further, the unsaturated macromonomer is one or a combination of two or more of allyl polyoxyethylene ether macromonomer APEG, methoxypolyethylene glycol methacrylate macromonomer MPEGMA, methallyl alcohol polyoxyethylene ether MAPEG and isopentenol polyoxyethylene ether macromonomer IPEG, wherein the weight average molecular weight of the allyl polyoxyethylene ether macromonomer APEG is 1000-6000 g/mol.

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

the method comprises the following steps: dissolving the unsaturated small monomer A in a proper amount of water, and stirring for a period of time at room temperature; slowly dropwise adding butylammonium into the solution of the unsaturated small monomer A, slowly adding cucurbituril into the mixed solution, stirring at room temperature for a period of time, and filtering; and precipitating the filtered solution by using acetone, and then drying the solution under the condition of reduced pressure to obtain the cucurbituril macromonomer.

Step two: dissolving an unsaturated small monomer B, a chain transfer agent, an unsaturated macromonomer and a cucurbituril macromonomer in deionized water to generate a solution 1; an appropriate amount of initiator was dissolved in deionized water to produce solution 2.

Step three: respectively dropwise adding the solution 1 and the solution 2 generated in the step two, performing free radical polymerization reaction on the two, and stirring at a preset temperature after dropwise adding is completed; and then cooling to room temperature to obtain the polycarboxylate superplasticizer with a molecular structure containing a melon ring structure.

Further, the reaction temperature of the free radical polymerization reaction in the third step is 70-80 ℃, and the reaction time is 3-5 hours.

3. Has the advantages that:

(1) according to the invention, on the basis of the original comb structure, the melon rings are introduced to increase the steric hindrance of the water reducing agent, so that the polycarboxylate water reducing agent is not easy to adsorb montmorillonite, the ineffective adsorption of the polycarboxylate water reducing agent is reduced, the problem of clay tolerance of the existing polycarboxylate water reducing agent is solved, the dosage of the water reducing agent is reduced, and the effectiveness of the water reducing agent is greatly improved;

(2) compared with the polycarboxylate superplasticizer grafted with cyclodextrin, the mud-resistant polycarboxylate superplasticizer provided by the invention is more stable, and the synthetic route is more environment-friendly.

(3) Compared with the conventional polycarboxylate superplasticizer, the mud-resistant polycarboxylate superplasticizer grafted with the cucurbituril monomer has obviously better fluidity retention in cement slurry with high mud content.

Detailed Description

The preparation process of the anti-mud water reducer comprises the following steps: firstly, preparing a monomer for grafting cucurbituril, and then polymerizing the prepared monomer and other monomers under the action of an initiator by adopting a free radical polymerization method to obtain a polymerization product containing a cucurbituril monomer with large physical size, wherein the monomer is hydrophobic in the inner part and hydrophilic in the outer part.

The specific embodiment is as follows:

example 1:

step 1: 0.22g of methacrylic acid was dissolved in 30mL of water, stirred at room temperature for 10min, 0.22g of butylamine was slowly added dropwise to the methacrylic acid solution, 2.5g of cucurbituril was slowly added to the mixed solution, and then stirred at room temperature for 24h, and filtered. The reacted solution is precipitated by acetone and dried under reduced pressure to obtain the macromonomer grafted with cucurbituril.

Step 2: 7mL of water was placed in a two-port flask which was first filled with N₂Three washes were performed and heated to 80 ℃ in an oil bath. 2.2g of methacrylic acid, 0.2g of mercaptopropionic acid, 6.83g of APEG (side chain degree of polymerization of 23) and 0.67g of cucurbituril macromonomer were dissolved in 17mL of deionized water. 0.1g of azobisisobutyronitrile was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise for 2.5h and 2h, respectively, the temperature being kept constant at 80 ℃. After the dropwise addition, the temperature was maintained at 80 ℃ for a further 60 min. Then cooled to 25 ℃ room temperature. The polymer was isolated by precipitation with acetone. Then dissolving-precipitating for three times, collecting the final precipitate, soaking in acetone for 4h, and then distilling at 40 ℃ under reduced pressure for 48h to obtain the anti-mud polycarboxylic acid water reducing agent with a molecular structure containing a melon ring structure, wherein the molecular structural formula is as follows:

wherein the polymerization degrees a, b, x and n are 42, 1, 9 and 23 in sequence; the weight average molecular weight of the prepared polycarboxylate superplasticizer is 28530.

Example 2:

step 1: 0.22g methacrylic acid was dissolved in 30mL water, stirred at room temperature for 10min, and 0.22g butylamine was slowly added dropwise to the methacrylic acid solution. 3g of six-membered cucurbituril was slowly added to the mixed solution, followed by stirring at room temperature for 24 hours and filtration. The reacted solution is precipitated by acetone and dried under reduced pressure to obtain the macromonomer grafted with cucurbituril.

Step 2: 7mL of water was placed in a two-port flask which was first filled with N₂Three washes were performed and heated to 80 ℃ in an oil bath. 2g of acrylic acid, 2g of sodium hypophosphite, 9.2g of MPEGMA (side chain degree of polymerization of 35) and 0.63g of cucurbituril macromonomer were dissolved in 17mL of deionized water. 0.15g of ammonium persulfate was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise over 3.5h and 3h, respectively, the temperature being kept constant at 80 ℃. After the dropwise addition, the temperature was maintained at 80 ℃ for a further 60 min. Then cooled to 25 ℃ room temperature. The polymer was isolated by precipitation with acetone. Dissolving and precipitating for three times, collecting the final precipitate, soaking in acetone for 4h, and distilling at 40 ℃ under reduced pressure for 48h to obtain the anti-mud polycarboxylic acid water reducing agent with a molecular structure containing a melon ring structure; the molecular structural formula is as follows:

in the formula, the polymerization degrees a, b, x and n are 42, 1, 9 and 35 in sequence; the weight average molecular weight of the prepared polycarboxylate superplasticizer is 30530.

Example 3:

step 1: 0.25g of maleic anhydride was dissolved in 30mL of water, stirred at room temperature for 10min, and 0.22g of diisobutylamine was slowly added dropwise to the methacrylic acid solution. 3.5g of cucurbituril was slowly added to the mixed solution, followed by stirring at room temperature for 24 hours and filtration. The reacted solution is precipitated by acetone and dried under reduced pressure to obtain the macromonomer grafted with cucurbituril.

Step 2: 7mL of water was placed in a two-port flask which was first filled with N₂Three washes were performed and heated to 80 ℃ in an oil bath. 2g of acrylic acid, 0.2g of mercaptopropionic acid, 16.4g of IPEG (side chain degree of polymerization of 53) and 0.7g of cucurbituril macromonomer were dissolved in 17mL of deionized water. 0.16g of potassium persulfate was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise for 2.5h and 3h, respectively, the temperature being kept constant at 80 ℃. After the dropwise addition, the temperature was maintained at 80 ℃ for a further 60 min. Then cooled to 25 ℃ room temperature. The polymer was isolated by precipitation with acetone. Then dissolving-precipitating for three times, collecting the final precipitate, soaking in acetone for 4h, and then distilling at 40 ℃ under reduced pressure for 48h to obtain the anti-mud polycarboxylic acid water reducing agent with a molecular structure containing a melon ring structure, wherein the molecular structural formula is as follows:

in the formula, the polymerization degrees a, b, x and n are 38, 1, 9 and 53 in sequence; the weight average molecular weight of the prepared polycarboxylic acid water reducing agent is 31280.

Example 4:

step 1: 0.186 acrylic acid was dissolved in 30mL of water, stirred at room temperature for 10min, and 0.25g of n-butylamine was slowly added dropwise to the methacrylic acid solution. 4g of eight-membered cucurbituril was slowly added to the mixed solution, followed by stirring at room temperature for 24 hours and filtration. The reacted solution is precipitated by acetone and dried under reduced pressure to obtain the macromonomer grafted with cucurbituril.

Step 2: 7mL of water was placed in a two-port flask which was first filled with N₂Three washes were performed and heated to 80 ℃ in an oil bath. 2g of acrylic acid, 0.18g of mercaptoethanol, 19.8g of MAPEG (with a side chain degree of polymerization of 65) and 0.8g of cucurbituril macromonomer were dissolved in 17mL of deionized water. 0.1g of 30% strength hydrogen peroxide was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise for 2h and 2.5h, respectively, the temperature being kept constant at 80 ℃. After the dripping is finishedAnd keeping the temperature at 80 ℃ for 60 min. Then cooled to 25 ℃ room temperature. The polymer was isolated by precipitation with acetone. Then dissolving-precipitating for three times, collecting the final precipitate, soaking in acetone for 4h, and then distilling at 40 ℃ under reduced pressure for 48h to obtain the anti-mud polycarboxylic acid water reducing agent with a molecular structure containing a melon ring structure, wherein the molecular structural formula is as follows:

in the formula, the polymerization degrees a, b, x and n are 42, 1, 9 and 65 in sequence; the weight average molecular weight of the prepared polycarboxylate superplasticizer is 33280.

Example 5:

step 1: 0.184g of acrylic acid was dissolved in 30mL of water, stirred at room temperature for 10min, and 0.22g of sec-butylamine was slowly added dropwise to the methacrylic acid solution. 3g of six-membered cucurbituril was slowly added to the mixed solution, followed by stirring at room temperature for 24 hours and filtration. The reacted solution is precipitated by acetone and dried under reduced pressure to obtain the macromonomer grafted with cucurbituril.

Step 2: 7mL of water was placed in a two-port flask which was first filled with N₂Three washes were performed and heated to 80 ℃ in an oil bath. 2g of acrylic acid, 0.35g of sodium methallyl sulfonate, 33.3g of MPEGMA (side chain degree of polymerization 134) and 0.62g of cucurbituril macromonomer were dissolved in 17mL of deionized water. 0.15g of sodium persulfate was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise over 3.5h and 3h, respectively, the temperature being kept constant at 80 ℃. After the dropwise addition, the temperature was maintained at 80 ℃ for a further 60 min. Then cooled to 25 ℃ room temperature. The polymer was isolated by precipitation with acetone. Then dissolving-precipitating for three times, collecting the final precipitate, soaking in acetone for 4h, and then distilling at 40 ℃ under reduced pressure for 48h to obtain the anti-mud polycarboxylic acid water reducing agent with a molecular structure containing a melon ring structure, wherein the molecular structural formula is as follows:

in the formula, the polymerization degrees a, b, x and n are 45, 1, 9 and 134 in sequence; the weight average molecular weight of the prepared polycarboxylate superplasticizer is 36652.

Comparative example:

2g of acrylic acid, 0.2g of mercaptopropionic acid, and 19.8g of IPEG were dissolved in 17mL of deionized water. 0.16g of potassium persulfate was dissolved in 4mL of deionized water. The initiator solution and the monomer solution were then added dropwise for 2.5h and 3h, respectively, the temperature being kept constant at 80 ℃. After the dropwise addition, the temperature was maintained at 80 ℃ for a further 60 min. Then cooling to 25 ℃ room temperature; the molecular structural formula of the prepared polycarboxylic acid water reducing agent is as follows:

in the above formula, the polymerization degrees a, x and n are 5, 1 and 65 respectively, and the weight average molecular weight of the prepared polycarboxylic acid water reducing agent is 31326.

Performance testing

(1) Testing the fluidity of the cement paste:

the cement paste fluidity test method was performed in accordance with the method specified in GB/T8077-2012 "homogeneity test method for concrete admixture", and the initial fluidity and retention property thereof were measured, with the comparative example as a control group.

Table 1: cement paste fluidity test of different samples

The clay contained in the sandstone material has a large influence mainly on the initial water reduction and loss of the water reducing agent, and therefore, the influence on the initial dispersion and retention effect of the montmorillonite in the cement slurry is tested when the content of the montmorillonite is 1%. It can be seen from the above data that the acid ether ratio is larger, initially larger but holds slightly worse, while the acid ether ratio is smaller, it holds better but initially reduces water. However, it can be seen that the retention of the properties of the sample with the addition of grafted cucurbituril is slightly improved compared to the control.

(2) Testing the performance and the compressive strength of the concrete mixture:

the concrete mixture performance test is carried out according to the method specified in GB/T50080-2002 Standard of Performance test methods of common concrete mixtures, and the concrete strength test is carried out according to the method specified in GB 8076 plus 2008 concrete admixture and GB/T50081 plus 2002 method of mechanical Performance test methods of common concrete.

Table 2: concrete mixture performance testing and strength testing of different samples

It can be seen from the above data that the concrete results are more consistent with the net slurry results. The mud-resistant water reducing agent added with the grafted cucurbituril has improved retention performance and has no adverse effect on strength.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The mud-resistant polycarboxylate superplasticizer is characterized by comprising the following components in parts by weight: reacting the unsaturated small monomer A, butylammonium and cucurbituril to prepare cucurbituril macromonomer; carrying out free radical polymerization reaction on the unsaturated small monomer B, the unsaturated large monomer and the cucurbituril large monomer to prepare the polycarboxylic acid water reducing agent with cucurbituril as a grafting side chain in a molecular structure; the structural formula of the prepared polycarboxylic acid water reducing agent is specifically as follows:

in the formula, the polymerization degree a is an integer of 1-5000; the polymerization degree b is an integer of 1-5000; the polymerization degree x is an integer of 0-200; the number n of repeating units isAn integer of 1 to 200; r₁is-H or-CH₃or-COOH; r₂is-H or-CH₃；R₃is-H or-CH₃；R₄is-CH₂-or-CH₂-CH₂-or-C ═ O-; the ring structure in the above formula represents cucurbituril.

2. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: the unsaturated small monomer A is one or the combination of two of methacrylic acid and acrylic acid.

3. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: the cucurbituril is one or a combination of methacrylic acid and acrylic acid.

4. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: the unsaturated small monomer B is one or a combination of two or more of methacrylic acid, acrylic acid and maleic anhydride.

5. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: a chain transfer agent is also included in the free radical polymerization reaction; the chain transfer agent is one or the combination of two or more of sodium methyl propylene sulfonate, mercaptoethanol, mercaptopropionic acid and sodium hypophosphite.

6. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: the free radical polymerization reaction also comprises an initiator; the initiator is one or the combination of two or more of ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide or azodiisobutyronitrile.

7. The mud-resistant polycarboxylate superplasticizer according to claim 1, characterized in that: the unsaturated macromonomer is one or a combination of two or more of allyl polyoxyethylene ether macromonomer APEG, methoxypolyethylene glycol methacrylate macromonomer MPEGMA, methallyl alcohol polyoxyethylene ether MAPEG and prenyl alcohol polyoxyethylene ether macromonomer IPEG, wherein the weight average molecular weight of the allyl polyoxyethylene ether macromonomer APEG is 1000-6000 g/mol.

8. A preparation method of the anti-mud type polycarboxylate water reducer is used for preparing the anti-mud type polycarboxylate water reducer according to any one of claims 1 to 7, and is characterized in that: the method comprises the following steps:

the method comprises the following steps: dissolving the unsaturated small monomer A in a proper amount of water, and stirring for a period of time at room temperature; slowly dropwise adding butylammonium into the solution of the unsaturated small monomer A, slowly adding cucurbituril into the mixed solution, stirring at room temperature for a period of time, and filtering; precipitating the filtered solution with acetone, and then drying under a reduced pressure condition to obtain cucurbituril macromonomer;

step two: dissolving an unsaturated small monomer B, a chain transfer agent, an unsaturated macromonomer and a cucurbituril macromonomer in deionized water to generate a solution 1; dissolving a proper amount of initiator in deionized water to generate a solution 2;

9. The preparation method of the anti-mud polycarboxylate superplasticizer according to claim 8, characterized by comprising the following steps: in the third step, the reaction temperature of the free radical polymerization reaction is 70-80 ℃, and the reaction time is 3-5 h.