CN107459282B

CN107459282B - Clay inhibitor with delayed coagulation function and preparation method thereof

Info

Publication number: CN107459282B
Application number: CN201710814358.1A
Authority: CN
Inventors: 唐新德; 杨月青; 赵春丽; 岳远倩; 扈有志; 潘义川; 张彩珠; 刘涛; 庞来学
Original assignee: Shandong Jiaotong University
Current assignee: Shandong Jiaotong University
Priority date: 2017-09-11
Filing date: 2017-09-11
Publication date: 2020-06-30
Anticipated expiration: 2037-09-11
Also published as: CN107459282A

Abstract

The invention discloses a clay inhibitor with a delayed coagulation function, which is a product with 40% of solid content obtained by ARGET ATRP reaction of a star initiator, methacryloyloxyethyl trimethyl ammonium chloride, an oxidant, a reducing agent and a ligand; the star-shaped initiator is methacryloyloxyethyl trimethyl ammonium chloride, an oxidant, a reducing agent and a ligand, and the molar ratio of the methacryloyloxyethyl trimethyl ammonium chloride to the reducing agent to the ligand is 1: 10-200: 0.01-0.1: 0.5-5: 0.01-0.5. The invention also discloses a preparation method of the inhibitor, wherein the polymerization reaction can be carried out at room temperature, and the sensitivity to oxygen and the dosage of the catalyst are effectively reduced. The inhibitor is compounded with the industrial polycarboxylic acid water reducing agent, so that the adaptability of the water reducing agent to soil can be effectively improved, and higher construction requirements can be met.

Description

Clay inhibitor with delayed coagulation function and preparation method thereof

Technical Field

The invention relates to a clay inhibitor and a preparation method thereof, in particular to a clay inhibitor with a retarding effect and a preparation method thereof, belonging to the technical field of concrete admixtures in building materials.

Background

The polycarboxylate superplasticizer has the advantages of low mixing amount, high water reducing rate, good slump retaining performance, strong molecular structure adjustability, large high-performance potential and the like, and becomes a third-generation high-performance concrete water reducer. However, polycarboxylic acid water reducing agents also face a number of technical difficulties in practical use, of which the sensitivity to clay is most pronounced. In order to avoid the negative effect on concrete caused by high mud content of aggregate, the current commonly used solving measure is to wash the aggregate with high mud content or add a water reducing agent in an excessive amount. However, aggregate grading is damaged during washing, working procedures are increased, and construction period is affected; super-admixtures typically cause initial bleeding and segregation of the concrete and increase costs.

The clay in the sand and stone material is mainly montmorillonite soil and kaolin, has higher specific surface area and a layered structure, and is preferential to cement to adsorb a water reducing agent and free water, so that the problems of large slump loss, poor rheological property, reduced durability and strength and the like of concrete are caused. The surface of cement hydrated particles is mainly positively charged, while the surface of clay particles is negatively charged, so that the component containing cations is added into the polycarboxylic acid water reducing agent, and through electrostatic adsorption, the clay particles can be coated, so that a good anti-mud effect is achieved, and compared with a small-molecular cationic compound, the cationic polymer has unique advantages as a clay inhibitor.

The molecular configuration of the clay inhibitor itself is also of great concern for its effect on the effectiveness of the clay. The molecules of the star polymer contain a large number of short branched chains, the winding among the molecules is less, the acting force among the molecules is small, and the intrinsic viscosity of the star polymer is far smaller than that of linear molecules; the star polymer has a three-dimensional spherical structure, and molecules are not intertwined, so that the space volume is larger than that of a linear polymer with the same molecular weight, the steric hindrance effect is stronger, and the clay inhibitor with the star structure has higher adaptability and a dispersing effect.

The β -cyclodextrin (β -CD) has a slightly conical molecular structure, a large amount of hydroxyl exists outside a conical cavity to show hydrophilicity, the conical cavity is hydrophobic, the molecular weight is 1135, the spatial diameter is 0.8nm, the cavity depth is about 0.7-0.8 nm, and the cyclodextrin is taken as a functional group and is introduced into the clay inhibitor to generate a good effect.

At present, radical polymerization is mainly adopted for preparing the polycarboxylate water reducer and the clay inhibitor, the molecular weight distribution of the obtained polymer is wider, the active polymerization technology has the advantages of designable molecular structure, controllable molecular weight, narrow molecular weight distribution and the like, if the active polymerization technology is applied to the preparation of the polycarboxylate water reducer and the clay inhibitor, the active polymerization technology has important significance for constructing the polycarboxylate water reducer and the clay inhibitor with controllable molecular structures, and the active polymerization methods adopted in the field of the water reducer mainly comprise Atom Transfer Radical Polymerization (ATRP) and reversible addition-fragmentation chain transfer polymerization (RAFT). Chinese patents CN106084157A, CN106146765A, CN106146859A, CN106519142A, CN106750046A, CN103482897A, CN102002134A and CN105669913A disclose that polycarboxylic acid water reducing agent is prepared by ATRP technology, Chinese patent CN106519121A discloses that reinforced mud-resisting agent is prepared by ATRP technology, and Chinese patents CN105712650A, CN105669912A, CN105153375A, CN106749958A and CN106496447A disclose that polycarboxylic acid water reducing agent is prepared by RAFT polymerization. However, the above living polymerization process is relatively severe in conditions, and is generally conducted in the absence of oxygen in a hermetic seal at relatively high temperatures. For ATRP, the catalyst is a low-valence transition metal compound, is easy to oxidize and deactivate, and is not beneficial to mass production, storage and transportation; the catalyst and the ligand have relatively large dosage, high toxicity and high cost; the post-treatment of the polymer is complicated and the recovery of the catalyst and ligand is difficult. These are the main factors limiting the large-scale industrial production of ATRP.

The ATRP technology (ARGET ATRP) with the function of regenerating the electron transfer catalyst which is developed recently solves the problems of the current industrial application of ATRP to a certain extent and has great industrial application value. The principle is that a certain amount of catalyst reducing agent is added in the ATRP reaction at the same time, so that divalent copper ions generated in the ATRP process can be reversibly reduced into monovalent copper ions, thereby improving the activity of the catalyst and effectively reducing the use amount of the catalyst and corresponding ligands. ARGET-ATRP has the following advantages: 1) the reaction conditions are relatively mild and can be carried out in the presence of a small amount of oxygen and free radicals; 2) no new initiating free radical or active species are generated in the reduction process of the reducing agent; 3) the catalyst is a stable high-valence transition metal compound, which is beneficial to mass production, storage and transportation; 4) the catalyst and ligand used in the system are relatively small in dosage (the dosage of the Cu catalyst can be reduced to several ppm), so that the post-polymerization treatment is simplified; 5) the used catalyst reducing agent has low toxicity (FDA certification) and is easy to obtain. These all contribute to further realizing the industrial production of ATRP, but the search finds that no report of preparing the clay inhibitor with the retardation by adopting the ARGET ATRP technology is found at present.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a clay inhibitor with a retarding effect and a preparation method thereof.

The clay inhibitor with the delayed coagulation function is a product with the solid content of 40% obtained by reacting a star initiator, methacryloyloxyethyl trimethyl ammonium chloride, an oxidant, a reducing agent and a ligand through atom transfer radical polymerization (ARGET ATRP) with an electron transfer catalyst regeneration function, and is characterized in that the star initiator is a product with the solid content of 40%, wherein the mole ratio of the methacryloyloxyethyl trimethyl ammonium chloride to the oxidant to the reducing agent to the ligand is 1 (10-200) to (0.01-0.1) to (0.5-5) to (0.01-0.5), the star initiator is prepared by dissolving 11.35g (0.01mol) of β -cyclodextrin in 60mL of anhydrous N, N-Dimethylformamide (DMF) according to the following proportion, adding the mixture into 100mL of a three-neck flask, adding 7.07g (0.07 mol) of triethylamine as a proton absorbent, stirring the mixture in ice for 0.5h under the nitrogen atmosphere, adding 16.1g (0.07 mol) of 2-isopropyl bromide in the three-neck flask, adding the mixture into 10mL of triethylamine as a three-neck flask, dropwise adding the mixture into the three-neck flask under the nitrogen atmosphere, filtering the three-neck flask, adding the mixture into a water solution under the water bath, adding the three-neck flask under the water bath, filtering, adding the three-neck flask under the water bath, reacting, adding the three-butyl bromide solution under the water, adding the water, reacting, adding the water under the water₂(cupric bromide) or CuCl₂(copper chloride); the reducing agent is Vc (vitamin C); the ligand is PMDETA (pentamethyldiethylenetriamine) and Me₆TREN (Tris [2- (dimethylamino) ethyl ester)]Amine) or bpy (bipyridine).

The preparation method of the clay inhibitor with the delayed coagulation function comprises the steps of halogenating cyclodextrin to obtain a star-shaped initiator, initiating polymerization of cationic monomer methacryloyloxyethyl trimethyl ammonium chloride by an atom transfer radical polymerization (ARGET ATRP) method with an electron transfer catalyst regeneration function at room temperature, and further processing the polymer to obtain a product with the solid content of 40%, namely the clay inhibitor with the delayed coagulation function.

Further, the preferable preparation method of the clay inhibitor with the retardation effect is as follows: dissolving a star initiator and methacryloyloxyethyl trimethyl ammonium chloride in a liquid mixed by an organic solvent and deionized water according to a set molar ratio of 1-2: 0.1-1, sequentially adding an oxidant, a reducing agent and a ligand, and stirring at room temperature for reaction for 3-5 hours; then dialyzing in deionized water to remove residual monomers and other impurities to obtain a star-shaped methacryloyloxyethyl trimethyl ammonium chloride polymer, and adjusting the solid content of the product to 40% by a solution concentration mode to obtain the clay inhibitor with the delayed coagulation function; wherein the organic solvent is N, N-Dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).

Wherein: the star initiator is methacryloyloxyethyl trimethyl ammonium chloride, oxidant, reductant and ligand, and the molar ratio of the star initiator to the oxidant to the ligand is 1 (10-200) to 0.01-0.1 to 0.5 to 0.01-0.5. Most preferred are: the mole ratio of the star initiator, namely methacryloyloxyethyl trimethyl ammonium chloride, the oxidant, the reducing agent and the ligand is 1 (50-100), 0.01-0.1, 0.5-3 and 0.05-0.5.

The invention takes cyclodextrin esterification products as an initiator, utilizes an active polymerization technology to prepare the clay inhibitor with controllable molecular structure and retarding coagulation, and provides a new method for preparing the anti-mud agent. The clay inhibitor with the retarding effect is compounded with the industrial polycarboxylate superplasticizer, so that the adaptability of the polycarboxylate superplasticizer to soil can be effectively improved, the high construction requirement can be met, and the clay inhibitor has a good application prospect.

The invention has the beneficial effects that:

1. ARGET ATRP adopted by the invention is an active polymerization technology, and the obtained clay inhibitor has the advantages of regular structure, controllable molecular weight, narrow molecular weight distribution and the like;

2. the invention adopts ARGET-ATRP technology, takes bivalent copper/ligand as catalyst, reduces part of bivalent copper into monovalent copper by reducing agent, thereby generating active species, but keeps the ratio of the monovalent copper to the bivalent copper higher, and still can keep acceptable polymerization rate. The advantages are that the dosage of catalyst and ligand is reduced, and the sensitivity of polymerization to oxygen is reduced.

3. The clay inhibitor prepared by the invention has a star topology structure, and can improve the self-dispersibility of the anti-clay agent and the adsorption capacity to soil; the cationic component has a coating effect on soil particles to form a protective layer, so that the adsorption of the soil on the polycarboxylic acid water reducing agent can be effectively inhibited, and the dispersibility of the concrete is improved;

4. compared with small molecules, the β -cyclodextrin has larger steric hindrance, so that the mud-resisting agent taking β -cyclodextrin as a core is difficult to enter the soil layers through the blocking effect, and the blocking effect is formed between the soil layers, thereby effectively inhibiting the adsorption of the soil to the polycarboxylic acid water reducing agent and further improving the adaptability of the water reducing agent to the soil.

5, β -cyclodextrin group can enhance the slump retaining ability of the polycarboxylate superplasticizer and improve the water retention and cohesiveness of concrete.

Detailed Description

The present invention will be further understood from the following specific examples, which should not be construed as limiting the scope of the invention.

Example 1:

(1) preparation of Star initiators

β -cyclodextrin (11.35g, 0.01mol) is dissolved in 60mL of anhydrous N, N-Dimethylformamide (DMF), the obtained solution is added into a 100mL three-necked bottle, triethylamine (7.07g, 0.07mol) is added to serve as a proton absorbent, the obtained solution is stirred in an ice-water bath for 0.5h under a nitrogen atmosphere, 2-bromine isobutyryl bromide (16.1g, 0.07mol) is dissolved in 10mL of anhydrous DMF, then the obtained solution is added into a constant pressure dropping funnel, dropwise added into the three-necked bottle, after the dropwise addition is finished, the obtained solution reacts at room temperature for 24h under the nitrogen atmosphere, after the reaction is finished, the reaction solution is filtered to remove salt, and the filtrate is precipitated in anhydrous ethanol, filtered, washed with the anhydrous ethanol, and dried in vacuum at 50 ℃ overnight, so that the star initiator containing the terminal group bromine is obtained.

(2) Preparation of clay inhibitors

Dissolving the star initiator (0.01mol) obtained in the step (1) and methacryloyloxyethyl trimethyl ammonium chloride (0.5mol) into a mixed solution of dimethyl sulfoxide and deionized water in a volume ratio of 2:1, and uniformly mixing and stirring. 0.0001mol of copper bromide, 0.005mol of Vc0.0005 mol and 0.0005mol of bipyridine are added in sequence, and the reaction is carried out for 3h at room temperature under mild stirring. The reaction product was placed in a dialysis bag and dialyzed against deionized water for 36 hours (water change every 12 hours). Concentrating the residual solution in the dialysis bag to obtain clay inhibitor with solid content of 40%, which is named ACP 1.

Example 2:

this example prepared ACP2 as an anti-sliming agent in the same manner as in example 1, except that the amount of methacryloyloxyethyltrimethylammonium chloride in step (2) was 1.0 mol.

Example 3:

this example prepared ACP3 as an anti-sliming agent in the same manner as in example 1, except that the amount of methacryloyloxyethyltrimethylammonium chloride in step (2) was 1.5 mol.

Example 4:

this example prepared anti-sliming ACP4 in the same manner as in example 2, except that step (2) was reacted at room temperature for 4 hours with mild stirring.

Example 5:

this example prepared anti-sliming ACP5 in the same manner as in example 2, except that step (2) was reacted at room temperature for 5 hours with mild stirring.

Example 6:

this example prepares anti-sliming ACP6 in the same manner as in example 2, except that 0.0005mol of copper bromide, vc0.025mol, and 0.0025mol of bipyridine were added in this order in step (2).

Example 7:

this example prepares the anti-mud agent ACP7 in the same manner as in example 2 except that in step (2) the catalyst was copper bromide 0.001mol, Vc0.05mol and bipyridine 0.005mol, which were added in this order.

Testing the fluidity of the cement paste:

referring to GB8077-2000 'test method for homogeneity of concrete admixture', when the solid mixing amount of a commercial polycarboxylate superplasticizer is 0.13% of the mass of cement and the water-cement ratio is 0.29, the initial net slurry fluidity and the 60min net slurry fluidity are respectively 290mm and 295mm in a test.

When the solid content of a commercial polycarboxylic acid water reducer is 0.13 percent of the mass of the cement, the content of montmorillonite is 1 percent of the mass of the cement and the water-cement ratio is 0.29, the initial net slurry fluidity and the 60min net slurry fluidity are respectively tested to be 225mm and 150 mm.

When the solid content of a commercial polycarboxylate water reducer is 0.13 percent of the mass of cement, the amount of a clay inhibitor accounts for 7 percent of the solid content of the polycarboxylate water reducer, the content of montmorillonite accounts for 1 percent of the mass of the cement, and the water-cement ratio is 0.29, the initial net slurry fluidity and the 60min fluidity are tested (table 1).

TABLE 1 test results of fluidity of cement paste in various conditions of examples

The test result of the fluidity of the cement paste shows that: the existence of montmorillonite has great influence on the fluidity of cement paste: the fluidity of the ordinary cement paste mixed with the commercial polycarboxylic acid water reducing agent is initially 290mm and reaches 295mm after 60 min; the fluidity of the cement paste mixed with the commercial polycarboxylic acid water reducing agent and 1 percent of montmorillonite is only 225mm initially, and is reduced to 150mm after 60 min. The clay inhibitor prepared by the invention is compounded with the polycarboxylic acid water reducing agent, although the initial fluidity is reduced (average 203mm) under the condition of containing 1% of montmorillonite, the net slurry fluidity is improved (average 217mm) after 60min, which shows that the clay inhibitor and the commercial polycarboxylic acid water reducing agent are compounded, the dispersing performance of the polycarboxylic acid water reducing agent is inhibited to a certain extent in the early stage, and the dispersing performance is gradually released along with the time. The clay inhibitor is a polymer of a cationic monomer, the ammonium group with positive charges can be preferentially adsorbed on the surface of clay, a layer of coating layer is formed on the surface of the clay, the cyclodextrin macromolecular structure positioned on the outer side can play a role in steric hindrance, the polycarboxylate superplasticizer molecules are prevented from being close to clay particles, and then the polycarboxylate superplasticizer molecules are prevented from entering the interlayer of montmorillonite, so that the mud resistance effect is achieved. Therefore, the clay inhibitor prepared by the invention is beneficial to improving the dispersibility and the retention performance of the cement paste, has good mud resistance and slow setting effect, and has positive effect on inhibiting the side effect of the clay in the cement concrete.

Claims

1. A clay inhibitor with a delayed coagulation function is a product with a solid content of 40% obtained by reacting a star initiator, methacryloyloxyethyl trimethyl ammonium chloride, an oxidant, a reducing agent and a ligand through atom transfer radical polymerization (ARGETATRP) with an electron transfer catalyst regeneration function, wherein the star initiator is prepared by dissolving 11.35g, namely 0.01mol of β -cyclodextrin in 60mL of anhydrous N, N-Dimethylformamide (DMF) according to the following proportion, adding the mixture into a 100mL three-necked flask, adding 7.07g, namely 0.07mol of triethylamine as a proton absorbent, stirring for 0.5h in an ice-water bath under a nitrogen atmosphere, dissolving 16.1g, namely 0.07mol of 2-bromoisobutyryl bromide in 10mL of anhydrous DMF, adding the obtained solution into a dropping funnel, dropwise adding the obtained solution into the three-necked flask, reacting for 24h under the nitrogen atmosphere at room temperature after the dropwise adding is finished, filtering and desalting a reaction solution, precipitating a filtrate in anhydrous ethanol, washing the obtained star filtrate, carrying out vacuum filtration, filtering, washing the obtained product with water, and drying the obtained product under a constant pressure, and obtaining CuBr of the oxidant at 50 ℃ under a reaction temperature₂(cupric bromide) or CuCl₂(copper chloride); the reducing agent is Vc (vitamin C); the ligand is PMDETA (pentamethyldiethylenetriamine) and Me₆TREN (Tris [2- (dimethylamino) ethyl ester)]Amine) or bpy (bipyridine); the clay inhibitor with the delayed coagulation function is prepared by the following method: dissolving a star initiator and methacryloyloxyethyl trimethyl ammonium chloride in a liquid mixed by an organic solvent and deionized water according to a set molar ratio of 1-2: 0.1-1, sequentially adding an oxidant, a reducing agent and a ligand, and stirring at room temperature for reaction for 3-5 hours; then dialyzed against deionized water to remove residual monomers and other impuritiesObtaining a star-shaped methacryloyloxyethyl trimethyl ammonium chloride polymer, and adjusting the solid content of the product to 40% in a solution concentration mode to obtain the clay inhibitor with the delayed coagulation function; wherein the organic solvent is N, N-Dimethylformamide (DMF) or dimethyl sulfoxide (DMSO);

the method is characterized in that:

the star-shaped initiator is methacryloyloxyethyl trimethyl ammonium chloride, an oxidant, a reducing agent and a ligand, and the molar ratio of the methacryloyloxyethyl trimethyl ammonium chloride to the reducing agent to the ligand is 1 (50-100) (0.01-0.1) (0.5-3) (0.05-0.5).