Solid polycarboxylate superplasticizer as well as preparation method therefor and use thereof

Abstract

A solid polycarboxylate superplasticizer, preparation method, and use. A monohydroxyl/monoamino polyoxyethylene ether or derivative thereof and unsaturated benzenesulfonic acid small monomer having the effects of crack resistance, shrinkage reduction and catalysis are added to a reactor at one time by a one-pot process, mixed and stirred, followed by vacuum dehydration under heating conditions or an esterification reaction under the introduction of a protective gas. After the reaction is completed and cooled, slicing or milling is performed to obtain the solid polycarboxylate superplasticizer. The superplasticizer has crack resistance and shrinkage reduction while ensuring initial dispersion performance. An organic solvent is not used, and a green environmental protection effect is achieved. The esterification rate is high, reaction conditions are mild, energy consumption is low, and operation steps are simple. The superplasticizer is easy to slice or mill and convenient to realize industrial production, with a good market prospect.

Claims

1. A preparation method for a solid polycarboxylate superplasticizer, comprising the following steps: (1) mixing an unsaturated acid monomer, an unsaturated benzenesulfonic acid monomer, an oxidizing agent, a reducing agent, and a chain transfer agent to carry out a redox free radical polymerization reaction to obtain a polycarboxyl polymer; and (2) mixing the polycarboxyl polymer with a monohydroxyl/monoamino polyoxyethylene ether to carry out a reaction, and after the reaction is completed and cooled, performing slicing or milling to obtain a solid polycarboxylate superplasticizer; the solid polycarboxylate superplasticizer has a structure as follows: ##STR00012## wherein R.sub.1, R.sub.2, and R.sub.3 are selected from H, CH.sub.3, COOH, or CHCH.sub.3CH.sub.3, and the R.sub.2 and the R.sub.3 are not COOH simultaneously; a is equal to 0 or 1; A is O or NH; b and c are integers; x, y, and z are positive integers, and b+c is equal to 22-105; and x+y+z is equal to 23-63.

2. The preparation method according to claim 1, wherein in step (1), a molar ratio of the unsaturated acid monomer, the unsaturated benzenesulfonic acid monomer, the oxidizing agent, the reducing agent, and the chain transfer agent is 1:(0.03-0.1):(0.03-0.2):(0.03-0.1):(0.01-0.05).

3. The preparation method according to claim 1, wherein in step (1), the unsaturated benzenesulfonic acid monomer is vinylbenzenesulfonic acid.

4. The preparation method according to claim 1, wherein in step (1), the unsaturated acid monomer is at least one of acrylic acid, methacrylic acid, butenoic acid, 4-methyl-2-pentenoic acid, maleic acid, maleic anhydride, itaconic acid, or itaconic anhydride.

5. The preparation method according to claim 1, wherein in step (1), the redox free radical polymerization reaction is carried out at 5-50 C., and a reaction time is 1-5 h.

6. The preparation method according to claim 1, wherein in step (2), a molar ratio of the monohydroxyl/monoamino polyoxyethylene ether to the polycarboxyl polymer is (3-8):1; a structure of the monohydroxyl/monoamino polyoxyethylene ether is: ##STR00013## wherein A is O or NH; and both b and c are an integer, and b+c is equal to 22-105.

7. The preparation method according to claim 1, wherein in step (2), the reaction refers to vacuumizing or introducing a protective gas to carry out a reaction at 100-150 C. for 2-5 h.

8. The preparation method according to claim 1, wherein in step (2), a molecular weight (M.sub.n) of the solid polycarboxylate superplasticizer is 10,200-38,500 g/mol.

Description

DESCRIPTION OF THE EMBODIMENTS

(1) In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort shall fall within the scope of protection of the present invention.

(2) All test materials, reagents and the like used in the following embodiments, unless otherwise specified, are conventionally available.

(3) Those without specific technologies or conditions in the embodiments are used according to technologies or conditions described in documents in the art or instructions of products.

Comparative Example 1

(4) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(5) Step 1: 1 mol of acrylic acid, 0.1 mol of maleic anhydride, 0.12 mol of ammonium persulfate, 0.1 mol of ascorbic acid, and 0.02 mol of mercaptoethanol were used to carry out a redox free radical polymerization reaction at 25 C. for 4 h to obtain a polycarboxyl polymer (M.sub.n=4,500 g/mol).

(6) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 8 mol of monomethoxy polyethylene glycol (M.sub.n=3,000 g/mol) were subjected to vacuum dehydration under heating and stirring conditions. When the temperature of the system reached 130 C., 0.05 mol of concentrated sulfuric acid was added, and continued vacuumizing was performed to carry out a reaction for 5 h. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 89%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 285,000 g/mol.

(7) ##STR00003##

Example 1

(8) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(9) Step 1: 1 mol of itaconic acid, 0.03 mol of 2-vinylbenzenesulfonic acid, 0.04 mol of hydrogen peroxide, 0.1 mol of sodium bisulfite, and 0.01 mol of mercaptoacetic acid were used to carry out a redox free radical polymerization reaction at 20 C. for 2.5 h to obtain a polycarboxyl polymer (M.sub.n=3,000 g/mol, a=1).

(10) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 3 mol of a monoamino EO-PO random copolymer (M.sub.n=2,400 g/mol, b=30, c=18) were used to carry out a reaction in a reactor at 100 C. for 5 h under the introduction of argon as a protective gas. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 96%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 10,200 g/mol.

(11) ##STR00004##

Example 2

(12) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(13) Step 1: 1 mol of acrylic acid, 0.04 mol of 3-vinylbenzenesulfonic acid, 0.03 mol of ammonium persulfate, 0.1 mol of sodium sulfite, and 0.02 mol of 2-mercaptopropionic acid were used to carry out a redox free radical polymerization reaction at 30 C. for 3 h to obtain a polycarboxyl polymer (M.sub.n=3,500 g/mol, a=1).

(14) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 7 mol of a monohydroxyl EO-PO random copolymer (M.sub.n=5,000 g/mol, b=83, c=22) were used to carry out a reaction in a reactor at 110 C. for 4.5 h under the introduction of nitrogen as a protective gas. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 93%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 38,500 g/mol.

(15) ##STR00005##

Example 3

(16) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(17) Step 1: 1 mol of methacrylic acid, 0.05 mol of 4-vinylbenzenesulfonic acid, 0.08 mol of sodium persulfate, 0.1 mol of sodium formaldehyde sulfoxylate, and 0.05 mol of 3-mercaptopropionic acid were used to carry out a redox free radical polymerization reaction at 45 C. for 2 h to obtain a polycarboxyl polymer (M.sub.n=4,000 g/mol, a=0).

(18) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 6 mol of a monohydroxyl EO-PO random copolymer (M.sub.n-4,600 g/mol, b=90, c=10) were used to carry out a reaction in a reactor at 120 C. for 4 h under the introduction of helium as a protective gas. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 93%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 31,600 g/mol.

(19) ##STR00006##

Example 4

(20) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(21) Step 1: 1 mol of maleic acid, 0.04 mol of 3-vinylbenzenesulfonic acid, 0.2 mol of potassium persulfate, 0.1 mol of ascorbic acid, and 0.04 mol of sodium methylallyl sulfonate were used to carry out a redox free radical polymerization reaction at 50 C. for 1.5 h to obtain a polycarboxyl polymer (M.sub.n=3,000 g/mol, a=0).

(22) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 8 mol of monomethoxy polyethylene glycol (M.sub.n=1,000 g/mol, b=22, c=0) were used to carry out a reaction at 130 C. for 3 h under vacuumizing. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 97%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 11,000 g/mol.

(23) ##STR00007##

Example 5

(24) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(25) Step 1: 1 mol of maleic anhydride, 0.05 mol of 2-vinylbenzenesulfonic acid, 0.15 mol of ammonium persulfate, 0.1 mol of sodium ascorbate, and 0.03 mol of dodecanethiol were used to carry out a redox free radical polymerization reaction at 5 C. for 1 h to obtain a polycarboxyl polymer (M.sub.n=5,000 g/mol, a=0).

(26) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 4 mol of monomethoxy polyethylene glycol (M.sub.n=3,000 g/mol, b=67, c=0) were used to carry out a reaction at 150 C. for 2 h under vacuumizing. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 95%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 17,000 g/mol.

(27) ##STR00008##

Example 6

(28) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(29) Step 1: 1 mol of itaconic anhydride, 0.05 mol of 4-vinylbenzenesulfonic acid, 0.2 mol of hydrogen peroxide, 0.05 mol of erythorbic acid, and 0.05 mol of sodium hypophosphite were used to carry out a redox free radical polymerization reaction at 10 C. for 3 h to obtain a polycarboxyl polymer (M.sub.n=8,000 g/mol, a=1).

(30) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 3 mol of monomethoxy polyethylene glycol (M.sub.n=2,000 g/mol, b=44, c=0) were used to carry out a reaction at 140 C. for 3 h under vacuumizing. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 96%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 14,000 g/mol.

(31) ##STR00009##

Example 7

(32) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(33) Step 1: 1 mol of butenoic acid, 0.1 mol of 4-vinylbenzenesulfonic acid, 0.1 mol of ammonium persulfate, 0.04 mol of erythorbic acid, and 0.05 mol of 3-mercaptopropionic acid were used to carry out a redox free radical polymerization reaction at 10 C. for 3.5 h to obtain a polycarboxyl polymer (M.sub.n=6,000 g/mol, a=0).

(34) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 4 mol of monomethoxy polyethylene glycol (M.sub.n=3,000 g/mol, b=67, c=0) were used to carry out a reaction at 120 C. for 4 h under vacuumizing. After the reaction was completed and cooled, slicing or milling was performed, and a sample was taken for GPC detection, which had an esterification rate of 94%. Then, a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 18,000 g/mol was obtained.

(35) ##STR00010##

Example 8

(36) A preparation method for a solid polycarboxylate superplasticizer includes the following steps.

(37) Step 1: 1 mol of 4-methyl-2-pentenoic acid, 0.1 mol of 4-vinylbenzenesulfonic acid, 0.1 mol of ammonium persulfate, 0.04 mol of erythorbic acid, and 0.05 mol of 3-mercaptopropionic acid were used to carry out a redox free radical polymerization reaction at 10 C. for 4 h to obtain a polycarboxyl polymer (M.sub.n=3,000 g/mol, a=0).

(38) Step 2: 1 mol of the polycarboxyl polymer obtained in step 1 and 8 mol of monomethoxy polyethylene glycol (M.sub.n=3,000 g/mol, b=67, c=0) were used to carry out a reaction at 130 C. for 4.5 h under vacuumizing. After the reaction was completed and cooled, a sample was taken for GPC detection, which had an esterification rate of 95%. Then, slicing or milling was performed to obtain a solid polycarboxylate superplasticizer with a molecular weight (M.sub.n) of 25,000 g/mol.

(39) ##STR00011##

(40) Physical and chemical property test of the solid polycarboxylate superplasticizers prepared in the above examples and comparative example: With reference to the standard of China Building Materials Association High Performance Superplasticizers of Solid Polycarboxylates, the appearance, ash content, moisture content, fineness and bulk density of the samples obtained in Example 1 to Example 8 and Comparative Example 1 were tested. Results are shown in Table 1.

(41) TABLE-US-00001 TABLE 1 Physical and chemical properties of solid polycarboxylate superplasticizers prepared in various examples and comparative example Fineness Ash Moisture (0.315 mm Bulk content/ content/ sieve density/ Sample Appearance % % residue)/% (g/cm.sup.3) Comparative Uniform color 0.47 0.88 2.73 0.58 Example 1 and slight caking Example 1 Uniform 0.43 0.47 1.54 0.62 color and no caking Example 2 Uniform 0.39 0.52 1.73 0.61 color and no caking Example 3 Uniform 0.38 0.41 1.19 0.64 color and no caking Example 4 Uniform 0.47 0.28 1.67 0.62 color and no caking Example 5 Uniform 0.46 0.69 2.05 0.60 color and no caking Example 6 Uniform 0.41 0.57 1.76 0.61 color and no caking Example 7 Uniform 0.37 0.43 1.85 0.61 color and no caking Example 8 Uniform 0.40 0.71 2.11 0.60 color and no caking

(42) With reference to the GB/T 8077-2012 Methods for Testing Uniformity of Concrete Admixtures, a paste fluidity test was carried out on the samples obtained in Comparative Example 1 and Example 1 to Example 8. A water-binder ratio was 0.29, and a doping amount of a superplasticizer was a solid doping amount of a cementing material. Results are shown in Table 2. As can be seen, compared with Comparative Example 1, the samples prepared by the method in Example 1 to Example 8 have better dispersion and dispersion retention performance.

(43) TABLE-US-00002 TABLE 2 Paste fluidity and gradual loss of different samples in examples and comparative example Paste fluidity/mm Sample Doping amount 0 h 1 h Comparative 0.15% 225 185 Example 1 Example 1 226 189 Example 2 228 187 Example 3 236 197 Example 4 225 185 Example 5 229 189 Example 6 227 193 Example 7 227 196 Example 8 236 190

(44) Concrete performance test: With reference to the GB8076-2008 Concrete Admixtures, the slump loss, concrete strength and 28 d shrinkage ratio of the samples obtained in Comparative Example 1 and Example 1 to Example 8 were tested. Results are shown in Table 3. When a solid doping amount of an admixture is 1.0 wt % (relative to a use amount of cement), the 28 d shrinkage ratio in various examples is significantly reduced compared with that in Comparative Example 1.

(45) TABLE-US-00003 TABLE 3 Concrete slump retaining performance and early mechanical performance of different samples Slump (mm)/ Compressive 28 d slump strength/ Shrink- Doping flow (mm) MPa age Sample amount 0 h 1 h 3 d 7 d 28 d ratio Com- 0.2% 210/560 185/460 27.4 33.7 46.8 63 parative Example 1 Example 1 215/565 190/485 28.6 36.8 47.7 40 Example 2 215/570 195/495 29.5 36.3 48.3 39 Example 3 215/585 210/475 28.6 35.4 47.6 43 Example 4 225/560 200/465 29.4 34.5 48.6 36 Example 5 215/565 210/495 29.5 33.8 48.4 39 Example 6 220/580 205/495 28.3 33.9 48.5 41 Example 7 220/560 215/485 27.1 34.9 48.6 43 Example 8 230/570 210/490 26.1 35.6 47.9 45

(46) In Comparative Example 1, a strong acid catalyst, such as concentrated sulfuric acid, needs to be added to catalyze an esterification reaction after dehydration is completed. Without stirring in time, the catalyst is not immediately dispersed evenly in the system, leading to carbonization and other side reactions and affecting the final performance. Meanwhile, an addition process also has potential safety hazards.

(47) The products prepared in various examples of the present invention have a significantly reduced 28 d shrinkage ratio and an anti-cracking effect. In addition, the esterification rate in the examples is obviously improved, indicating that the unsaturated benzenesulfonic acid small monomer used in the present invention has a catalysis effect. It can also be seen by comparison that the products prepared in the examples of the present invention have better milling performance and less sticking and caking.

(48) The description of the examples above is intended to facilitate the understanding and application of the present invention by those of ordinary skill in the art. It is obvious to persons familiar with the art that various modifications to these examples can be easily made, and general principles described herein can be applied to other examples without creative effort. Therefore, the present invention is not limited to the above examples, and all improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention shall fall within the scope of protection of the present invention.