CN103613306A - Hyperbranched poly(amine-ester) structure-containing polycarboxylic water reducer and preparation method thereof - Google Patents

Abstract

The invention discloses a polycarboxylate concrete water reducer containing a novel hyperbranched polyamine-ester structure. The hyperbranched monomer D contains a plurality of terminal carboxyl groups, and the molecule contains a plurality of amino groups and ester groups. Under the conditions, it is copolymerized with unsaturated carboxylic acid, unsaturated sulfonic acid and unsaturated polyether in aqueous solution to obtain a new type of polycarboxylic acid-based concrete water reducer. The water reducer of the present invention, to a certain extent, improves the disadvantages of existing water reducers such as poor fluidity, large slump loss, and poor adaptability to cement. The invention has the following beneficial effects: (1) novel molecular structure, containing more effective groups; (2) low dosage, high water reducing rate, good dispersibility and fluidity, high compressive strength, and can be widely used in many (3) The synthesis process is simple and easy to control, and the synthesis process is green and pollution-free.

Description

A kind of polycarboxylate water-reducer containing hyperbranched polyamine-ester structure and preparation method thereof

technical field

The invention relates to the technical field of concrete water reducers, in particular to a polycarboxylate water reducer containing a hyperbranched polyurethane-ester structure, and to a preparation method thereof.

Background technique

At present, my country's infrastructure construction field continues to develop at a high speed, and the demand for concrete is huge. As one of the most widely used admixtures in concrete, water reducers are used in various engineering constructions. The water reducer can keep the work degree of cement paste, mortar and concrete unchanged and significantly reduce its mixing water consumption, and can significantly increase the strength of concrete, improve the frost resistance and impermeability of concrete or reduce the amount of cement. According to the development process of water reducing agent, it can be divided into: the first generation of ordinary water reducing agent (water reducing rate ≥ 8%); the second generation of high efficiency water reducing agent (water reducing rate ≥ 12%); the third generation of high performance water reducing agent Aqua. Among them, ordinary water reducing agents mainly include lignosulfonate, molasses, etc.; high-efficiency water reducing agents mainly include naphthalene sulfonate formaldehyde condensate, polycyclic aromatic hydrocarbon sulfonate formaldehyde condensate, melamine (melamine) water reducing Sulfamate superplasticizer, aliphatic hydroxysulfonate superplasticizer, etc. In China, these two types of water reducers are still widely used. However, these water reducing agents have many shortcomings and limitations, such as low water reducing rate, rapid loss of concrete slump, high alkali content, etc. The performance of their compound products is very unstable, which often affects the construction and performance of concrete. , it is difficult to meet the construction requirements of high performance concrete. The third-generation high-performance water reducer refers to the polycarboxylate water reducer, which has low dosage, high water reducing rate, good dispersion, low slump loss, strong post-enhancement effect, and the production process is environmentally friendly and non-toxic. Pollution and many other advantages have been widely studied and promoted.

In Japan and developed countries in Europe and the United States, polycarboxylate high-performance water reducers occupy a very high market share, while the market share in my country is relatively low. At the same time, my country's research on it started late, and compared with developed countries, there is still a big gap in the structure and performance of the polycarboxylate-based water reducer. Therefore, the research on polycarboxylate high-performance water reducer is more significant. the

Polycarboxylate superplasticizers have superior performance, but the types of raw materials used for their synthesis are limited, the mechanism of water reduction is not yet clear, the adaptability to different types of cement is poor, and the relationship between structure and performance is unclear. Therefore, it is imperative to study the modification and new structure of polycarboxylate superplasticizer. the

CN102002134A discloses a hyperbranched polymer and a hyperbranched polycarboxylate water reducer, using methyl acrylate, ethanolamine, 2-bromoethanol, and malonic acid as raw materials to synthesize bromine-terminated hyperbranched polyamine-ester core molecules , using cuprous bromide and 2.3-bipyridine as catalysts and complexing agents, using atom transfer radical polymerization to graft acrylic acid and monomethoxy-terminated allyl polyethylene glycol onto bromine-terminated hyperbranched Polyurethane can be used to obtain hyperbranched polymers, which can be used in water reducers and have the advantages of low dosage, high water reducing rate, small slump loss, good compatibility with cement, and strong frost resistance. the

CN101580353A discloses a copolymer main chain formed by polymerizing one of tert-butyl acrylate and tert-butyl methacrylate with sodium methacrylic acid sulfonate and allyl polyoxyethylene ether, and then composed of acrylic acid and methacrylic acid One of the superplasticizers that is polycondensed with ethylenediamine to form a hyperbranched polyamide structure grafted to both ends of the main chain. It has the advantages of low dosage, high water reducing rate, small slump loss, good compatibility with cement, no corrosion to steel bars, and strong frost resistance. the

Invention content

In order to solve the problems in the above technologies, the present invention provides a polycarboxylate water reducer containing a hyperbranched polyamine-ester structure (having multiple effective functional groups such as carboxyl, amino and ester groups). Under the same concrete volume and water-cement ratio, the water-reducing agent has different degrees of improvement in water-reducing rate, dispersion performance, slump retention, and adaptability to cement.

The invention also provides a preparation method of the polycarboxylate water reducer. the

A polycarboxylate water reducer containing a hyperbranched polyurethane structure, the structural formula is as follows:

 Among them, a, b, c, d are natural numbers,

n is a natural number from 8 to 100;

R ₁ , R ₂ , and R ₃ are H atoms or methyl groups, respectively,

M is an H atom or an alkali metal cation,

x= ; y=2 ^g , where g is a natural number from 1 to 4, representing the algebra of the hyperbranched polymer.

The polycarboxylate water reducer is characterized in that a:b:c:d = 3.0~7.0:0.5~1.5:1.0~2.0:0.5~1.0. the

The water reducer involved in the present invention is formed by copolymerization of unsaturated carboxylic acid (A), unsaturated sulfonic acid (B), unsaturated polyether (C) and a new hyperbranched monomer (D);

The molar ratio of the polycarboxylate water reducer monomers A, B, C, and D is 3.0~7.0:0.5~1.5:1.0~2.0:0.5~1.0.

The general formula of the hyperbranched monomer structure is

                                                    

                                                    

where x= ;y= ^2g ;

g is a natural number from 1 to 4, representing the algebra of the hyperbranched polymer.

The structural formula of the preferred unsaturated carboxylic acid is

, wherein, R ₁ is a H atom or a methyl group, and M is a H atom or an alkali metal cation.

The structural formula of the preferred unsaturated sulfonic acid is

   

   

, wherein _R2 is an H atom or a methyl group, and M is an H atom or an alkali metal cation.

The structural formula of the preferred unsaturated polyether is

, wherein R ₂ is an H atom or a methyl group, and the molecular weight is 400~3000.

The hyperbranched monomer is obtained through the following steps: reacting diethanolamine and methyl acrylate to generate AB ₂ monomer, reacting AB ₂ monomer with propylene alcohol to obtain a hydroxyl-terminated hyperbranched polymer, and using succinic anhydride to terminate group modification to obtain hyperbranched monomers.

In the preparation method of the hyperbranched monomer, the molar ratio of propylene alcohol to AB ₂ monomer is preferably 1:1~15.

The preparation method of described water reducing agent preferably comprises the following steps:

(1) Preparation of new hyperbranched monomer: Under nitrogen protection, diethanolamine reacts with methyl acrylate to form AB ₂ monomer; under the catalysis of p-toluenesulfonic acid, AB ₂ monomer reacts with allyl alcohol to obtain terminal hydroxyl hyperbranched Polymerization; carry out end group modification with succinic anhydride to obtain hyperbranched type monomer with the terminal hydroxyl hyperbranching that makes;

(2) The monomer unsaturated carboxylic acid, unsaturated sulfonic acid, unsaturated polyether and hyperbranched monomer are respectively prepared into aqueous solution, and the initiator and unsaturated sulfonic acid, unsaturated poly The mixed solution of ether and hyperbranched monomer is added dropwise to the aqueous solution of unsaturated carboxylic acid in batches, and the reaction is stirred. After the dropwise addition, it is kept at 85-90°C for 4 hours, and the pH is adjusted to 7~7.5 to obtain Polycarboxylate water reducer with polyurethane structure;

The mixed solution of initiator and unsaturated sulfonic acid, unsaturated polyether and hyperbranched monomer is added dropwise once and three times every half hour;

The initiator is ammonium persulfate, potassium persulfate or sodium persulfate, and the amount of the initiator is 2.0% to 3.0% of the total mass of the monomer.

The amount of the polycarboxylate water-reducer in concrete is 0.2-1.0%. the

The following is a detailed description of the preparation of a polycarboxylate water reducer, which mainly includes the following steps:

(1) Preparation of new hyperbranched monomers

After passing nitrogen gas into the three-neck flask for 10 min, add an appropriate amount of diethanolamine and methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then a certain amount of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then methanol was distilled off under reduced pressure to obtain AB ₂ monomer. Take an appropriate amount of AB2 monomer in a three-necked flask with nitrogen, add a certain amount of allyl alcohol (as a nuclear molecule) and an appropriate amount of catalyst p-toluenesulfonic acid, stir until all solid reagents are dissolved, then raise the temperature to 85 °C and stir for 24 After h, the product was washed with ether and then distilled under reduced pressure to obtain hyperbranched hydroxyl groups. Take an appropriate amount of hydroxyl-terminated hyperbranched and succinic anhydride to dissolve in tetrahydrofuran respectively, mix the two after dissolving, use DMAP as a catalyst, reflux the reaction until the acid value of the system is 1/2 of the initial value, and distill off the solvent under reduced pressure to obtain hyperbranched chemical monomer.

By controlling the molar ratio of the core molecule to the _AB2 monomer, hyperbranched monomers of different generations can be obtained. When the molar ratio of the two is 1:1, the product is G1; when the molar ratio of the two is 1:3, the product is G2; when the molar ratio of the two is 1:7, the product is G3; when the molar ratio of the two is 1:15, the product is G4. Wherein the reaction formula of G2 is shown in the following formula:

(2) Preparation of polycarboxylate water reducer

Monomer B is configured into a certain proportion of aqueous solution; the remaining A, C, and D monomers are mixed to form a certain mass fraction of an aqueous solution; 2.0~3.0% of the total mass of the four monomers is used as an initiator to form a certain proportion of aqueous solution . Put the aqueous solution of B in the reactor, stir and heat up to 60~80°C, then add the mixed solution of the initiator and the monomer dropwise in batches, with an interval of half an hour. to 85-90°C, continue to stir and react for 4-6 hours, and then adjust the pH to 7-7.5 with a NaOH solution with a mass fraction of 25%-40%, to obtain a new type of polycarboxylic acid-based water reducer with a hyperbranched structure.

Among them, the structural formula of the polycarboxylate water reducer containing the G2 hyperbranched structure is as follows:

为                     

              ； in,

for

;

a, b, c, d, n are natural numbers.

During the hydration process of cement, coagulation occurs due to the van der Waals force between particles and the influence of other different charges, resulting in the formation of a flocculated structure in concrete. Water reducing agent is a kind of surfactant. After adding to the cement dispersion system, it will produce wetting and adsorption at the solid-liquid interface, form an adsorption layer or an electric double layer, and disperse the system. Its dispersion stability is mainly determined by the balance between electrostatic repulsion and van der Waals attraction. When the water reducer is added to the cement system, a part of the polar group is anchored on the surface of the cement particle, and the other part extends into the aqueous solution to provide electrostatic repulsion; the longer polyalkoxy side chain increases the steric hindrance effect; the structure of the water reducer The ionic groups in the water dissociate into ions and adsorb on the cement particles, so that the cement particles are charged and generate electrostatic repulsion. In this way, the flocculation structure in the cement paste is destroyed, the water in it is released, the amount of free water increases, and the cement particles have better dispersion and fluidity. the

Beneficial effects of the present invention:

The polycarboxylate water-reducing agent of the present invention has a comb-shaped structure, and the molecular skeleton is composed of the main chain and more side chains. It has the characteristics of high water-reducing rate and good dispersibility, and can make cement particles have better dispersibility. The agglomeration phenomenon of cement particles can be effectively prevented; the preparation method is simple to operate, green and pollution-free.

Detailed ways

Example 1

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 57.37g of AB ₂ monomer into a three-necked flask with nitrogen, add 5.81g of allyl alcohol and 0.32g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C, stir and react at a constant temperature for 24 hours, then rinse with ether The product is then distilled under reduced pressure to obtain the hyperbranched terminal hydroxyl group of the G2 generation. Take 53.57g of G2-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.56g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D1.

(2) Take 0.79g of sodium methacryl sulfonate to prepare an aqueous solution with a mass fraction of 25%; take 1.26g of acrylic acid, 18.00g of TPEG-2400, and 4.68g of hyperbranched monomer D1 to prepare an aqueous solution with a mass fraction of 25% After the aqueous solution is mixed; take 0.74g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G2-PC1. the

Example 2

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 57.37g of AB ₂ monomer into a three-necked flask with nitrogen, add 5.81g of allyl alcohol and 0.32g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C, stir and react at a constant temperature for 24 hours, then rinse with ether The product is then distilled under reduced pressure to obtain the hyperbranched terminal hydroxyl group of the G2 generation. Take 53.57g of G2-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.56g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D2.

(2) Take 0.40g of sodium methacryl sulfonate to prepare an aqueous solution with a mass fraction of 25%; take 2.16g of acrylic acid, 18.00g of TPEG-2400, and 4.68g of hyperbranched monomer D2 to prepare an aqueous solution with a mass fraction of 25% After the aqueous solution is mixed; take 0.76g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G2-PC2. the

Example 3

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 66.93g of AB ₂ monomer into a three-necked flask with nitrogen, add 2.90g of allyl alcohol and 0.35g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C, stir and react at a constant temperature for 24 hours, then rinse with ether After the product is distilled under reduced pressure, the G3 generation terminal hydroxyl hyperbranching is obtained. Take 58.62g of G3-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.59g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D3.

(2) Take 0.79g of sodium methacryl sulfonate to prepare an aqueous solution with a mass fraction of 25%; take 1.26g of acrylic acid, 18.00g of TPEG-2400, and 9.86g of hyperbranched monomer D3 to prepare an aqueous solution with a mass fraction of 25% After the aqueous solution is mixed; take 0.90g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G3-PC1. the

Example 4

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 66.93g of AB ₂ monomer into a three-necked flask with nitrogen, add 2.90g of allyl alcohol and 0.35g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C, stir and react at a constant temperature for 24 hours, then rinse with ether After the product is distilled under reduced pressure, the G3 generation terminal hydroxyl hyperbranching is obtained. Take 58.62g of G3-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.59g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D4.

(2) Take 0.79g of sodium methacrylate to prepare an aqueous solution with a mass fraction of 25%; take 1.26g of acrylic acid, 9.00g of APEG-1200, and 9.86g of hyperbranched monomer D4 to prepare an aqueous solution with a mass fraction of 25%. After the aqueous solution is mixed; take 0.63g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G3-PC2. the

Example 5

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 57.37g of AB ₂ monomer in a three-necked flask with nitrogen gas, add 1.16g of allyl alcohol and 0.29g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C and stir for 24 hours, then rinse with ether After the product is distilled under reduced pressure, the G4 generation terminal hydroxyl hyperbranching is obtained. Take 61.15g of G4-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.61g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D5.

(2) Take 0.79g of sodium methacrylate to prepare an aqueous solution with a mass fraction of 25%; take 1.26g of acrylic acid, 18g of TPEG-2400, and 20.24g of hyperbranched monomer D5 to prepare an aqueous solution with a mass fraction of 25% After mixing; take 1.21g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G4-PC1. the

Example 6

(1) After passing nitrogen gas into the three-necked flask for 10 min, add 105.14 g of diethanolamine and 50 mL of methanol, and stir magnetically at room temperature under continuous nitrogen protection until the diethanolamine is completely dissolved. Then, 86.09 g of methyl acrylate was slowly added dropwise. After the dropwise addition, the temperature of the water bath was raised to 40° C. and kept for 4 hours, and then the methanol was distilled off under reduced pressure to obtain the AB ₂ type monomer. Take 57.37g of AB ₂ monomer in a three-necked flask with nitrogen gas, add 1.16g of allyl alcohol and 0.29g of p-toluenesulfonic acid, stir until all solid reagents are dissolved, raise the temperature to 85°C and stir for 24 hours, then rinse with ether After the product is distilled under reduced pressure, the G4 generation terminal hydroxyl hyperbranching is obtained. Take 61.15g of G4-generation terminal hydroxyl hyperbranching and 40.03g of succinic anhydride and dissolve them in 100mL and 300mL of tetrahydrofuran respectively, mix the two after dissolving, dissolve 0.61g of DMAP in 20mL of tetrahydrofuran, then slowly add it dropwise to the mixed system, and reflux Reaction until the acid value of the system is 1/2 of the initial value, and the solvent is distilled off under reduced pressure to obtain hyperbranched monomer D5.

(2) Take 0.59g of sodium methacrylate to prepare an aqueous solution with a mass fraction of 25%; take 2.16g of acrylic acid, 18g of TPEG-2400, and 10.12g of hyperbranched monomer D5 to prepare an aqueous solution with a mass fraction of 25% After mixing; take 0.93g of ammonium persulfate and configure it into a 25% aqueous solution. Put the aqueous solution of sodium methacrylate in a three-necked flask, stir and heat up to 60°C, then add 1/4 of the mixed solution of initiator and monomer dropwise, then raise the temperature to 80°C, and add dropwise every half an hour The mixed solution of the initiator and the monomer was added dropwise for three times. After the dropwise addition, the temperature was raised to 85~90°C, and the stirring reaction was continued for 4 hours, and then the pH was adjusted to 7~7.5 with a 40% NaOH solution to obtain A new type of polycarboxylate water reducer with hyperbranched structure, denoted as G4-PC2. the

For the new polycarboxylate water reducer prepared in the above 6 examples, the cement paste experiment and concrete performance test experiment were carried out respectively. Note: All tests refer to the national standard GB/T 8077-2000 "Concrete Admixture Homogeneity Test Method" and the national standard GB8076-2008 "Concrete Admixture"; the cement used is Portland cement 42.5. the

A kind of hyperbranched polymer disclosed in CN102002134A mentioned in the background technology and a hyperbranched polycarboxylate-based water-reducer were used as control 1, and the water-reduced agent disclosed in CN101580353A was used as control 2 to carry out cement paste experiment and concrete performance test experiment . the

Table 1 Test results of fluidity of cement slurry

Table 2 concrete test results

It can be seen that the novel polycarboxylate water-reducer synthesized by the present invention has high water-reducing rate, good dispersibility and fluidity, and strong compression resistance, and can be widely used in various concretes.

the

Claims (10)

1. A polycarboxylic acid water reducing agent containing a hyperbranched polyurethane structure is characterized by having a structural formula as follows:

wherein a, b, c and d are natural numbers,

n is a natural number from 8 to 100;

R₁、R₂、R₃are each a hydrogen atom or a methyl group,

m is a hydrogen atom or an alkali metal cation,

x=

；y=2^gwherein g is a natural number from 1 to 4, representing the generation number of the hyperbranched polymer.

2. The polycarboxylic acid-based water reducing agent according to claim 1, characterized in that a: b: c: d = 3.0 to 7.0: 0.5-1.5: 1.0-2.0: 0.5 to 1.0.

3. A preparation method of a polycarboxylic acid water reducer containing a hyperbranched polyurethane structure is characterized in that unsaturated carboxylic acid, unsaturated sulfonic acid, unsaturated polyether and a hyperbranched monomer are copolymerized to obtain the polycarboxylic acid water reducer containing the hyperbranched polyurethane structure;

the hyperbranched monomer has a general structural formula of

Wherein, x =

；y=2^g ；

g is a natural number from 1 to 4, representing the generation number of the hyperbranched polymer.

4. The process according to claim 3, wherein the unsaturated carboxylic acid has the formula

Wherein R is₁Is H atom or methyl, M is H atom orAn alkali metal cation.

5. The process according to claim 3 or 4, wherein the unsaturated sulfonic acid has the formula

Wherein R is₂Is H atom or methyl, M is H atom or alkali metal cation.

6. The process according to claim 3 or 4, wherein the unsaturated polyether has the formula

Wherein R is₂Is H atom or methyl, and has molecular weight of 400-3000.

7. The method according to claim 3, wherein the hyperbranched monomer is obtained by: diethanolamine and methyl acrylate react to generate AB₂Monomer, AB₂The monomer reacts with propylene alcohol to obtain a hydroxyl-terminated hyperbranched polymer, and succinic anhydride is used for carrying out end group modification to obtain a hyperbranched monomer.

8. The process of claim 7, wherein the allylic alcohol is reacted with AB₂The molar ratio of the monomers is 1:1 to 15.

9. The method of claim 3, comprising the steps of:

(1) preparing a novel hyperbranched monomer: diethanolamine and propylene under the protection of nitrogenMethyl ester reacts to generate AB₂A monomer; AB under the catalysis of p-toluenesulfonic acid₂Reacting the monomer with allyl alcohol to obtain a hydroxyl-terminated hyperbranched polymer; performing end group modification on the prepared hydroxyl-terminated hyperbranched monomer by succinic anhydride to obtain a hyperbranched monomer;

(2) respectively preparing monomer unsaturated carboxylic acid, unsaturated sulfonic acid, unsaturated polyether and hyperbranched monomer into aqueous solution, dropwise adding mixed solution of initiator, unsaturated sulfonic acid, unsaturated polyether and hyperbranched monomer into the aqueous solution of unsaturated carboxylic acid in batches at 60-80 ℃, stirring for reaction, keeping the temperature at 85-90 ℃ for 4 hours after dropwise adding, and adjusting the pH to 7-7.5 to obtain the polycarboxylate-type water reducer containing a hyperbranched polyurethane structure;

the mixed solution of the initiator, the unsaturated sulfonic acid, the unsaturated polyether and the hyperbranched monomer is dripped once every half hour for three times;

the initiator is ammonium persulfate, potassium persulfate or sodium persulfate, and the dosage of the initiator is 2.0-3.0% of the total mass of the monomers.

10. The polycarboxylic acid-based water-reducing agent according to claim 1 or 2 or the polycarboxylic acid-based water-reducing agent obtained by the production method according to any one of claims 3 to 9, characterized in that the amount of the broken solid incorporated in concrete is 0.2 to 1.0%.