CN112707670B

CN112707670B - Cross-linked concrete viscosity regulator and preparation method thereof

Info

Publication number: CN112707670B
Application number: CN201911288796.4A
Authority: CN
Inventors: 钟丽娜; 黄艳婷; 方云辉; 陈国荣; 柯余良; 朱少宏; 郭元强
Original assignee: Kezhijie New Material Group Co Ltd
Current assignee: Chongqing Jianyan Kezhijie Building Materials Co ltd
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2022-04-22
Anticipated expiration: 2039-12-12
Also published as: CN112707670A

Abstract

The invention relates to the technical field of concrete materials in building materials, in particular to a cross-linking type concrete viscosity regulator and a preparation method thereof. The regulator is obtainable by aqueous solution free radical polymerization of a monomer mixture comprising a polymerizable reducing agent having a tertiary amino group and a cellulose ether structure, an unsaturated acid, an unsaturated ester, a crosslinking agent. Tertiary amino groups capable of reacting with an oxidizing agent are introduced to a cellulose ether structure to form active free base points, and polymerization of unsaturated acid and unsaturated ester is continuously initiated, so that a plurality of polymer molecular chains of unsaturated acid and unsaturated ester are introduced to the cellulose ether structure, and the molecular chains can greatly improve the solubility of the cellulose ether. The concrete viscosity regulator prepared by the invention is compounded with the water reducing agent for use, the phenomena of flocculation and layering are avoided, the wrapping property and the fluidity of the concrete can be obviously improved, and the phenomenon of bleeding and segregation is obviously reduced, so that the workability of the concrete is improved.

Description

Cross-linked concrete viscosity regulator and preparation method thereof

Technical Field

The invention relates to the technical field of concrete materials in building materials, in particular to a cross-linking type concrete viscosity regulator and a preparation method thereof.

Background

Under the situation that natural sandstone resources are deficient and the state continuously strengthens the ore resources and the environmental protection, machine-made sandstone, sea sand, recycled aggregate and the like become main products of sandstone aggregate for basic facilities such as buildings, roads, bridges and the like in China. The use of machine-made sandstone, sea sand, recycled aggregate and other poor-quality sandstone generally leads to the deterioration of the workability of concrete, and is mainly reflected in that: the medium and low strength concrete has poor cohesiveness and has segregation and bleeding phenomena; the high-strength concrete has too high viscosity, which is not beneficial to pumping construction and the like. In engineering, the workability of concrete is improved by adding a concrete viscosity regulator to achieve good construction performance.

Chinese patent application CN 107382131 a, published as 2017, 11, 24, discloses a concrete viscosity modifier and a preparation method thereof, mainly including modified soy protein, cellulose ether, acrylic acid, acryloyloxyethyltrimethyl ammonium chloride, to solve the compatibility problem of concrete, however, the patent uses an emulsion polymerization method for preparation, introduces a lot of surfactants, and these surfactants may have adverse effects on the performances of the concrete, such as air content, strength, durability, etc.

At present, the most widely used concrete viscosity regulators in China are cellulose series and propylene series, wherein the cellulose series is powder, the cellulose series is generally introduced into concrete by compounding with a water reducing agent, and a good concrete viscosity modification effect can be achieved when the mixing amount is 0.02-0.04% of the finished product of a single ton of water reducing agent. In practical application, it is found that the viscosity modifying effect of the cellulose ether with higher viscosity (such as 10 to 30 ten thousand mPas) on concrete is better than that of the cellulose ether with lower viscosity (such as 400 mPas), generally, the higher the viscosity, the higher the molecular weight of the corresponding cellulose ether is, but the higher the viscosity is, the longer the dissolution time of the cellulose ether in the water reducing agent solution is, and the compatibility problem between the cellulose ether and the water reducing agent is also existed, and the delamination is easy to occur when the cellulose ether is placed, thereby affecting the use effect of the water reducing agent.

Therefore, it is very necessary to improve the solubility of cellulose ether while controlling the viscosity of the cellulose ether.

Disclosure of Invention

In order to solve the problem of solubility of a cellulose-based viscosity modifier under the precondition of controlling the viscosity of cellulose ether mentioned in the background art, the invention provides a crosslinking-type concrete viscosity modifier, which is obtained by polymerizing a monomer mixture comprising a polymerizable reducing agent, an unsaturated acid, an unsaturated ester and a crosslinking agent, wherein the polymerizable reducing agent has a tertiary amino group and a cellulose ether structure.

In the technical aspect of the above scheme, the cross-linking agent is one of ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1, 2-propylene glycol dimethacrylate, 1, 4-butylene glycol 2-methyl-2-acrylate, polypropylene glycol dimethacrylate and polyethylene glycol dimethacrylate.

In the technical scheme, further, the polymerizable reducing agent is prepared from a compound A and a compound B;

wherein, the structural formula of the compound A is shown as the formula (I):

in the formula, R₁Is methyl or ethyl;

R₂is (CH)₂)_nN is 1-10, or is a benzene ring, or is ethoxybenzene;

R₃is methyl or ethyl;

the structure of the compound B is shown as the formula (II):

wherein R is H, CH₃、CH₂CH₂OH, or

In the above technical solution, the compound a further includes one of ethyl 2-diethylaminoacetate, ethyl 2-dimethylaminoacetate, ethyl 3-dimethylaminopropionate, ethyl 4- (dimethylamino) butyrate, ethyl 4- (2- (dimethylamino) ethoxy) benzoate, 2-dimethylaminoethyl benzoate, ethyl p-N, N-dimethylaminobenzoate, and methyl 4-diethylaminobenzoate.

In the above technical solution, the compound B is one of hydroxyethyl methyl cellulose ether, hydroxypropyl methyl cellulose ether, and hydroxypropyl methyl cellulose.

In the above aspect, the hydroxypropyl methylcellulose ether has a viscosity of 50 to 1000mPa · s.

In the above technical solution, further, the polymerizable reducing agent is prepared by the following steps:

dissolving a compound B in a proper amount of mixed solution of toluene and isopropanol, adding a compound A, carrying out transesterification reaction in the presence of a catalyst and a polymerization inhibitor, wherein the temperature of the transesterification reaction is 80-120 ℃, the reaction time is 5-15 h, and removing the solvent through reduced pressure distillation after the reaction is finished to obtain the polymerizable reducing agent.

In the above aspect, the molar ratio of the anhydroglucose units of compound a to compound B is 0.02 to 3:1, and preferably 0.1 to 1: 1.

In the technical aspect of the above scheme, further, the catalyst is concentrated sulfuric acid, p-toluenesulfonic acid or 4-dimethylaminopyridine, and the amount of the catalyst is 0.5-30% of the mass of the compound B.

In the technical scheme, the polymerization inhibitor is hydroquinone, phenothiazine or diphenylamine, and the amount of the polymerization inhibitor is 0.01-0.2% of the mass of the compound B.

In the above technical solution, further, the structure of the unsaturated acid is represented by formula (iii):

in the formula R₄Is H or COOH, R₅Is H or CH₃。

In the above aspect, further, the unsaturated acid includes acrylic acid and methacrylic acid.

In the technical aspect of the above scheme, further, the structure of the unsaturated ester is shown as formula (IV):

in the formula, R₆Is H or CH₃，R₇Is H or CH₃；R₈Is C_nH_2nOH or C_nH_2nPO₄，n＝1～20。

In the above aspect, the unsaturated ester is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, 2-methacryloyloxyethyl phosphate, and 2-methacryloyloxypropyl phosphate.

The invention also provides a preparation method of the cross-linked concrete viscosity regulator, which comprises the following preparation steps:

placing a polymerizable reducing agent and a proper amount of deionized water into a reactor, stirring and dissolving, dropwise adding a mixed solution of unsaturated acid, unsaturated ester and a crosslinking agent, an oxidant and a chain transfer agent into the reactor, adjusting the temperature to 10-50 ℃ for reaction, wherein the dropwise adding time is 1-3 h, keeping the temperature for 0.5-1.5 h after the dropwise adding is finished, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator.

In the technical aspect of the above scheme, further, the oxidizing agent is hydrogen peroxide or benzoyl peroxide.

In the above technical solution, the chain transfer agent is thioglycolic acid, mercaptopropionic acid, or mercaptoethanol.

In the technical scheme, the mass ratio of the unsaturated acid to the unsaturated ester to the macromolecular reducing agent to the oxidizing agent to the chain transfer agent to the crosslinking agent is 5-10: 1: 0.05-3: 1-3: 0.4-1.5: 0.01-5.

The concrete viscosity regulator provided by the invention relates to the following principles and beneficial effects:

the concrete viscosity regulator provided by the invention forms an active free base point by introducing tertiary amino groups capable of acting with an oxidant on a cellulose ether structure, and continuously initiates polymerization of unsaturated acid and unsaturated ester, namely, a plurality of polymer molecular chains of unsaturated acid and unsaturated ester are introduced on the cellulose ether structure, and the water-soluble molecular chains can greatly improve the solubility of the cellulose ether. The cross-linking agent is introduced to cross-link the viscosity modifier in a proper amount, so that the cellulose ether with good solubility can be prepared by micro-crosslinking on the premise of adopting the cellulose ether with lower viscosity, the bleeding segregation phenomenon is obviously reduced, and the tackifying effect of the concrete is improved.

The concrete viscosity regulator and the water reducing agent are compounded for use, the phenomena of flocculation and layering are avoided, the wrapping property and the fluidity of the concrete can be obviously improved, and the phenomenon of bleeding and segregation is reduced, so that the workability of the concrete is improved.

In a preferred embodiment, the solubility of the cellulose ether can be further improved by introducing a plurality of tertiary amino groups on the cellulose ether structure through the transesterification reaction of the compound A and the compound B provided by the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following description will clearly and completely describe the embodiments of the present invention, and obviously, the described embodiments are a part of the embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention also provides the following embodiments:

preparation of polymerizable reducing agent

Example 1:

4g of hydroxypropyl methyl cellulose ether with the viscosity of 400 mPa.s, 120g of toluene and 40g of isopropanol are added into a four-neck flask provided with a stirrer, a water separator, a thermometer and a nitrogen guide pipe, stirred and dissolved, then 1.5g of 2-diethylaminoethyl acetate, 0.3g of concentrated sulfuric acid and 0.001g of hydroquinone are added, the reaction temperature is 90 ℃ under the stirring condition, the reaction is carried out for 10 hours, and after the reaction is finished, the solvent is removed by reduced pressure distillation, so that the polymerizable reducing agent C1 is obtained.

Example 2:

4g of hydroxypropyl methylcellulose ether having a viscosity of 400 mPas, 120g of toluene and 40g of isopropyl alcohol were put in a four-necked flask equipped with a stirrer, a water separator, a thermometer and a nitrogen gas introduction tube and dissolved by stirring. Then 2g of 2-dimethylamino ethyl acetate, 0.8g of 4-dimethylaminopyridine and 0.001g of hydroquinone are added, the reaction temperature is 90 ℃ under the condition of stirring, the reaction lasts for 10 hours, the solvent is removed by reduced pressure distillation, and the polymerizable reducing agent C2 is obtained after the reaction is finished.

Example 3:

4g of 200 mPas viscosity hydroxypropyl methylcellulose ether, 120g of toluene and 40g of isopropyl alcohol were put into a four-necked flask equipped with a stirrer, a water separator, a thermometer and a nitrogen gas introduction tube and dissolved by stirring. Then adding 1.7g of 3-dimethyl amino ethyl propionate, 0.25g of concentrated sulfuric acid and 0.001g of phenothiazine, reacting for 10 hours at the reaction temperature of 90 ℃ under the condition of stirring, and removing the solvent by reduced pressure distillation after the reaction is finished to obtain the polymerizable reducing agent C3.

Example 4:

in a four-necked flask equipped with a stirrer, a water separator, a thermometer and a nitrogen gas introduction tube, 4g of 600mPa s hydroxypropyl methylcellulose ether, 120g of toluene and 40g of isopropyl alcohol were introduced and dissolved by stirring. Then adding 2.0g of 3-dimethyl amino ethyl propionate, 0.5g of 4-dimethyl aminopyridine and 0.001g of hydroquinone, reacting for 10h at the reaction temperature of 90 ℃ under the condition of stirring, and removing the solvent by reduced pressure distillation after the reaction is finished to obtain the polymerizable reducing agent C4.

Secondly, preparation of concrete viscosity regulator

Example 5

Placing 0.3g of polymerizable reducing agent C1 and 100g of deionized water in a reactor, stirring for dissolving, dropwise adding a mixed solution of 20g of acrylic acid, 4g of hydroxyethyl methacrylate and 2.5g of polyethylene glycol dimethacrylate, 2g of aqueous hydrogen peroxide and 0.7g of aqueous mercaptopropionic acid into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding is finished, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D1.

Example 6

Placing 0.25g of polymerizable reducing agent C2 and 100g of deionized water in a reactor, stirring for dissolving, dropwise adding a mixed solution of 20g of acrylic acid, 3g of hydroxyethyl methacrylate and 2.5g of polyethylene glycol dimethacrylate, 2.5g of aqueous hydrogen peroxide and 0.5g of aqueous mercaptoethanol into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D2.

Example 7

Placing 0.3g of polymerizable reducing agent C3 and 100g of deionized water in a reactor, stirring for dissolving, dropwise adding a mixed solution of 20g of acrylic acid, 4g of hydroxyethyl acrylate and 2.5g of polypropylene glycol dimethacrylate, 2.1g of aqueous hydrogen peroxide and 0.9g of aqueous thioglycolic acid into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D3.

Example 8

Placing 0.35g of polymerizable reducing agent C4 and 100g of deionized water in a reactor, stirring for dissolving, dropwise adding a mixed solution of 20g of acrylic acid, 3g of hydroxyethyl methacrylate and 0.8g of ethylene glycol dimethacrylate, 2g of aqueous hydrogen peroxide and 0.7g of aqueous mercaptopropionic acid into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding is finished, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D4.

Example 9

Placing 0.3g of polymerizable reducing agent C1 and 100g of deionized water in a reactor, stirring for dissolving, dropwise adding 20g of acrylic acid, 4g of hydroxyethyl acrylate and 1g of diethylene glycol dimethacrylate mixed solution, 2.2g of hydrogen peroxide aqueous solution and 0.8g of mercaptopropionic acid aqueous solution into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding is finished, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D5.

Example 10

Placing 0.3g of polymerizable reducing agent C1 and 100g of deionized water into a reactor, dropwise adding a mixed solution of 22g of acrylic acid, 3g of 2-methacryloyloxyethyl phosphate and 1.5g of polyethylene glycol dimethacrylate, 2g of aqueous hydrogen peroxide and 1.0g of aqueous thioglycolic acid into the reactor, reacting at room temperature for 1.5h, keeping the temperature for 1h after dropwise adding is finished, cooling to room temperature after the reaction is finished, and adjusting the pH to 6-7 by using liquid alkali to obtain the concrete viscosity regulator D6.

Concrete viscosity modifier samples synthesized in examples 5 to 10, commercially available cellulose ether modifiers (comparative examples, product types of HPMC, HPC, and HEC), and commercially available polycarboxylate superplasticizer mother liquor (product type of Point-TS8) were prepared into aqueous solutions, left to stand for 10 days, and the compatibility was observed, with the test results shown in table 1.

TABLE 1 compatibility test results with Water reducing Agents

Sample numbering	Compounded composition	Compound formula (quality ratio)	Compatibility
				1	Water reducing agent and water	50：500	Clear and no floccule
2	200 mPa.s HPMC, water reducing agent and water	0.15：50：500	Layered with floc
				3	400 mPa.s HPC + water reducing agent + water	0.15：50：500	Layered with floc
4	600mPa s HEC + water reducing agent + water	0.15：50：500	Layered with floc
				5	Example 5+ Water reducing agent + Water	2：50：500	Clear and no floccule
6	Example 6+ Water reducing agent + Water	2：50：500	Clear and no floccule
				7	Example 7+ Water reducing agent + Water	2：50：500	Clear and no floccule
8	Example 8+ Water reducing agent + Water	2：50：500	Clear and no floccule
				9	Example 9+ Water reducing agent + Water	2：50：500	Clear and no floccule
12	Example 10+ Water reducing agent + Water	2：50：500	Clear and no floccule

As can be seen from Table 1, the workability regulator obtained by the present invention can be well dissolved in the polycarboxylate water reducing agent solution, regardless of the same mass or solid content, while the comparative example and the polycarboxylate water reducing agent have a small amount of floc after standing for 10 days, indicating that the two are poorly compatible.

The water reducing agent and workability regulator compound samples in the table 1 were subjected to concrete tests, and concrete slump, slump with age, expansion, age-spread, bleeding distance and normal pressure bleeding rate were measured according to GB 8076 + 2008 "concrete admixture" with a mixing amount of 0.18% by mass of cement (folded into solid) using standard cement. Concrete and its production methodThe mixing ratio is as follows: cement 360kg/m³790kg/m of sand³Stone 1050kg/m³170kg/m of water³The results obtained are shown in table 2:

TABLE 2 concrete test results

The test results in table 2 show that the concrete viscosity modifiers prepared in the embodiments 5 to 10 of the invention can effectively improve the segregation and bleeding phenomena of the concrete, especially obviously improve the bleeding phenomena, and can also improve the slump retaining performance of the concrete compared with the comparative examples.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cross-linking type concrete viscosity regulator is characterized in that: which is obtained by polymerization of a monomer mixture comprising a polymerizable reducing agent having a tertiary amino group and a cellulose ether structure, an unsaturated acid, an unsaturated ester, a crosslinking agent;

the polymerizable reducing agent is prepared from a compound A and a compound B;

wherein, the structural formula of the compound A is shown as the formula (I):

in the formula, R₁Is methyl or ethyl;

R₂is (CH)₂) n and n are 1-10, or are benzene rings, or are ethoxybenzenes;

R₃is methyl or ethyl;

the structure of the compound B is shown as the formula (II):

wherein R is H, CH₃、CH₂CH₂OH, or

The structure of the unsaturated acid is shown as the formula (III):

in the formula R₄Is H or COOH, R₅Is H or CH₃；

The structure of the unsaturated ester is shown as the formula (IV):

2. The crosslinking-type concrete viscosity modifier according to claim 1, wherein: the cross-linking agent is one of ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1, 2-propylene glycol dimethacrylate, 2-methyl-2-acrylic acid-1, 4-butylene glycol ester, polypropylene glycol dimethacrylate and polyethylene glycol dimethacrylate.

3. The concrete viscosity modifier of claim 1, wherein: the compound A comprises one of 2-diethylaminoethyl acetate, 2-dimethylaminoethyl acetate, 3-dimethylaminoethyl propionate, ethyl 4- (dimethylamino) butyrate, ethyl 4- (2- (dimethylamino) ethoxy) benzoate, 2-dimethylaminoethyl benzoate, ethyl p-N, N-dimethylaminobenzoate and methyl 4-diethylaminobenzoate.

4. The concrete viscosity modifier of claim 1, wherein: the compound B is one of hydroxyethyl methyl cellulose ether, hydroxypropyl methyl cellulose ether and hydroxypropyl methyl cellulose.

5. The concrete viscosity modifier of claim 4, wherein: the viscosity of the hydroxypropyl methyl cellulose ether is 50 mPa.s-1000 mPa.s.

6. The crosslinking-type concrete viscosity modifier according to claim 1, wherein: the preparation steps of the polymerizable reducing agent are as follows:

7. The crosslinking-type concrete viscosity modifier according to claim 6, wherein: the molar ratio of the anhydroglucose units of the compound A to the anhydroglucose units of the compound B is 0.02-3: 1.

8. The crosslinking-type concrete viscosity modifier according to claim 6, wherein: the catalyst is concentrated sulfuric acid, p-toluenesulfonic acid or 4-dimethylaminopyridine, and the amount of the catalyst is 0.5-30% of the mass of the compound B.

9. The crosslinking-type concrete viscosity modifier according to claim 6, wherein: the polymerization inhibitor is hydroquinone, phenothiazine or diphenylamine, and the dosage of the polymerization inhibitor is 0.01-0.2 percent of the mass of the compound B.

10. The crosslinking-type concrete viscosity modifier according to claim 1, wherein: the unsaturated acid includes acrylic acid and methacrylic acid.

11. The crosslinking-type concrete viscosity modifier according to claim 1, wherein: the unsaturated ester is at least one of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, 2-methacryloyloxyethyl phosphate or 2-methacryloyloxypropyl phosphate.

12. The method for preparing a cross-linked concrete viscosity modifier according to any one of claims 1 to 11, comprising the steps of:

13. The method for preparing a cross-linked concrete viscosity modifier according to claim 12, characterized in that: the oxidant is hydrogen peroxide or benzoyl peroxide.

14. The method for preparing a cross-linked concrete viscosity modifier according to claim 12, characterized in that: the chain transfer agent is thioglycolic acid, mercaptopropionic acid or mercaptoethanol.

15. The method for preparing a cross-linked concrete viscosity modifier according to claim 12, characterized in that: the mass ratio of the unsaturated acid to the unsaturated ester to the polymerizable reducing agent to the oxidizing agent to the chain transfer agent is 5-10: 1: 0.05-3: 1-3: 0.4-1.5: 0.01-5.