CN112812238A - Polycarboxylate superplasticizer and preparation method and application thereof - Google Patents
Polycarboxylate superplasticizer and preparation method and application thereof Download PDFInfo
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- CN112812238A CN112812238A CN202011611651.6A CN202011611651A CN112812238A CN 112812238 A CN112812238 A CN 112812238A CN 202011611651 A CN202011611651 A CN 202011611651A CN 112812238 A CN112812238 A CN 112812238A
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- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
- C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/16—Sulfur-containing compounds
- C04B24/161—Macromolecular compounds comprising sulfonate or sulfate groups
- C04B24/163—Macromolecular compounds comprising sulfonate or sulfate groups obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/165—Macromolecular compounds comprising sulfonate or sulfate groups obtained by reactions only involving carbon-to-carbon unsaturated bonds containing polyether side chains
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
- C04B2103/302—Water reducers
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Abstract
The invention discloses a polycarboxylate superplasticizer which comprises the following raw materials: unsaturated polyoxyethylene ether monomer a, unsaturated carboxylic acid monomer b, unsaturated sulfonic acid monomer c, unsaturated phenyl monomer d, water, oxidant, reducing agent and optional auxiliary agent selected from chain transfer agent, gypsum excitant and defoaming agent. The invention also discloses a preparation method of the polycarboxylate superplasticizer and application of the polycarboxylate superplasticizer to a gypsum plasterboard. The polycarboxylate superplasticizer disclosed by the invention has the advantages of high water reduction, low air entraining, small influence on gypsum coagulation, simple process and environmental friendliness, does not influence starch gelatinization and migration to paper surface when used for producing gypsum plasterboards, and has good paper surface binding power.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a polycarboxylic acid water reducing agent, and a preparation method and application thereof.
Background
The natural gypsum cementing material product has the advantages of stable size, excellent shaping property, beautiful decoration, light weight, heat preservation, sound absorption, fire prevention and the like, and is a green environment-friendly building material which is vigorously promoted at home and abroad. However, the actual mixing water consumption of the building gypsum is far greater than the theoretical hydration water demand, so that the porosity of a hardened body is increased, the strength of the building gypsum is low, and the development of gypsum building materials is restricted all the time. The addition of the water reducing agent can simultaneously ensure good slurry rheological property and higher hardened body strength of the gypsum, and is a practical and effective way for modifying the building gypsum. At present, naphthalene water reducing agents are mostly adopted in industry to improve the flow property of anhydrite, but the naphthalene water reducing agents can release formaldehyde in the using process, thereby causing great pollution to the environment.
The polycarboxylic acid water reducing agent has gradually become a hotspot of research in the field of gypsum dispersing agents due to the advantages of high water reducing rate, environmental friendliness, no formaldehyde and the like. However, the existing polycarboxylic acid macromolecular water reducing agent product generally has the problems of large air entraining amount, serious retardation, poor adaptability of gypsum and paper surface bonding and the like. Therefore, it is necessary to develop a special polycarboxylic acid water reducing agent suitable for paper-surface gypsum boards aiming at the hydration characteristics of building gypsum.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a special polycarboxylic acid water reducing agent suitable for gypsum, in particular to a gypsum plasterboard and a preparation method thereof. According to the invention, the polycarboxylic acid water reducing agent is optimized and modified by compounding the multifunctional component, the gypsum hydration excitant and the defoaming agent, so that the obtained polycarboxylic acid water reducing agent has the advantages of high water reduction, low air entraining and small influence on gypsum coagulation, and is simple in process, green and environment-friendly.
Therefore, the invention provides a polycarboxylic acid water reducing agent in a first aspect, which comprises the following raw materials:
unsaturated polyoxyethylene ether monomer a, unsaturated carboxylic acid monomer b, unsaturated sulfonic acid monomer c, unsaturated phenyl monomer d, water, oxidant, reducing agent and optional auxiliary agent selected from chain transfer agent, gypsum excitant and defoaming agent.
According to the present invention, the "optional auxiliary selected from the group consisting of a chain transfer agent, a gypsum activator and a defoaming agent" means that the auxiliary may not be contained, and one or two or more auxiliary selected from the group consisting of a chain transfer agent, a gypsum activator and a defoaming agent may be contained.
According to some embodiments of the present invention, the molar ratio of monomer a to monomer b is 1 (1.5-3), preferably 1 (2-2.7).
According to some embodiments of the present invention, the molar ratio of monomer a to monomer c is 1 (0.5-3), preferably 1 (1-2).
According to some embodiments of the present invention, the molar ratio of monomer a to monomer d is 1 (0.1-0.5), preferably 1 (0.2-0.3).
According to some embodiments of the invention, the unsaturated sulfonic acid monomer c comprises a mixture of 2-acrylamido-2-methylpropanesulfonic acid and an unsaturated alkenyl sulfonate.
According to some embodiments of the invention, the unsaturated alkenyl sulfonate is at least one of sodium allyl sulfonate, potassium allyl sulfonate, ammonium allyl sulfonate, sodium methallyl sulfonate, potassium methallyl sulfonate, and ammonium methallyl sulfonate, preferably sodium methallyl sulfonate.
According to some preferred embodiments of the present invention, the mass ratio of the 2-acrylamido-2-methylpropanesulfonic acid to the unsaturated olefin sulfonate is (0.5 to 3):1, preferably (1 to 2): 1.
According to some embodiments of the invention, the unsaturated polyoxyethylene ether monomer a is methyl allyl polyoxyethylene ether, and the molecular structural formula of the methyl allyl polyoxyethylene ether is CH2＝C(CH3)-CH2-O-(C2H4O)n-H, wherein n-50-135, preferably n-85-115.
According to some embodiments of the present invention, the unsaturated carboxylic acid monomer b is selected from at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid, preferably acrylic acid or a mixture of acrylic acid and methacrylic acid.
According to some embodiments of the invention, the unsaturated phenyl monomer d is styrene and/or sodium styrene sulfonate, preferably sodium styrene sulfonate.
According to the present invention, the water may be deionized water.
According to some embodiments of the invention, the oxidizing agent is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate.
According to some embodiments of the invention, the reducing agent is selected from at least one of L-ascorbic acid, sodium bisulfite, sodium sulfite and sodium hypophosphite, preferably L-ascorbic acid.
According to some embodiments of the invention, the chain transfer agent is selected from at least one of mercaptoethanol, mercaptopropanol, mercaptoacetic acid, mercaptopropionic acid, and n-dodecanethiol.
According to some embodiments of the invention, the defoamer is selected from at least one of polyether defoamers, acetylenic diols, tributyl phosphate, and polyether modified silicon defoamers.
According to some embodiments of the invention, the gypsum excitant is selected from at least one of sodium sulphate, potassium sulphate, aluminium sulphate, iron sulphate, copper sulphate, sodium oxalate, potassium oxalate, alum, calcined alum, sodium silicate, potassium dichromate.
According to some embodiments of the present invention, the amount of the oxidizing agent is 0.3 to 1.5 wt% based on the total weight of the unsaturated polyoxyethylene ether monomer a, the unsaturated carboxylic acid monomer b, the unsaturated sulfonic acid monomer c, and the unsaturated phenyl monomer d.
According to some embodiments of the present invention, the reducing agent is present in an amount of 0.1 to 0.3 wt% based on the total weight of the unsaturated polyoxyethylene ether monomer a, the unsaturated carboxylic acid monomer b, the unsaturated sulfonic acid monomer c, and the unsaturated phenyl monomer d.
According to some embodiments of the present invention, the amount of the chain transfer agent is 0 to 0.5 wt% based on the total weight of the unsaturated polyoxyethylene ether monomer a, the unsaturated carboxylic acid monomer b, the unsaturated sulfonic acid monomer c, and the unsaturated phenyl monomer d.
According to some embodiments of the invention, the defoamer is present in an amount of 0.01 to 0.2% by weight of the polycarboxylate water reducer.
According to the invention, the weight of the gypsum excitant accounts for 1-5%, preferably 2-3% of the weight of the polycarboxylate superplasticizer.
The second aspect of the present invention provides a method for preparing a polycarboxylic acid water reducing agent according to the first aspect of the present invention, comprising the steps of:
s1, carrying out polymerization reaction on an unsaturated polyoxyethylene ether monomer a, an unsaturated carboxylic acid monomer b, an unsaturated sulfonic acid monomer c and an unsaturated phenyl monomer d in first water in the presence of an oxidant, a reducing agent and an optional chain transfer agent to obtain a polycarboxylic acid water reducer mother liquor;
and S2, mixing the polycarboxylate superplasticizer mother liquor obtained in the step S1 with second water and optional gypsum excitant, defoamer and neutralizer to obtain the polycarboxylate superplasticizer.
According to some embodiments of the present invention, the first water is added in step S1 in an amount to make the polycarboxylic acid water reducer mother liquor have a solid content of 40-60%, preferably 45-50%.
According to the invention, the weight ratio of the polycarboxylate superplasticizer mother liquor to the second water is not specifically limited, and the polycarboxylate superplasticizer mother liquor and the second water can be mixed in any proportion under the condition of ensuring that the polycarboxylate superplasticizer mother liquor and the second water can be uniformly mixed according to requirements. According to some embodiments of the invention, the weight ratio of the polycarboxylate superplasticizer mother liquor to the second water is (4-5): (5-6).
According to some embodiments of the invention, the step S1 includes: (1) mixing the first water, the unsaturated polyoxyethylene ether monomer a and the unsaturated phenyl monomer d to obtain a mixed solution;
(2) adding an oxidant into the mixed solution obtained in the step (1), then dropwise adding the solution A and the solution B, carrying out curing reaction to obtain a mother solution of the polycarboxylate superplasticizer,
the solution A is a mixed solution of an unsaturated carboxylic acid monomer B, an unsaturated sulfonic acid monomer c and water, and the solution B is a mixed solution of a reducing agent, a chain transfer agent and water.
According to some embodiments of the invention, in step (1), the temperature of the mixing is controlled to allow the reaction components to be sufficiently dissolved, preferably at 40-50 ℃.
According to some embodiments of the invention, in the step (2), the dropping time of the solution A and the solution B is 90-180min, and the solution B is dropped 30min later than the solution A, preferably at a constant speed.
According to some embodiments of the invention, in the step (2), the time of the aging reaction is 30 to 90 min.
According to some embodiments of the invention, in step (2), the temperature of the ripening reaction is 40 to 60 ℃, preferably 40 to 55 ℃.
According to some embodiments of the present invention, step S1 further includes adjusting the PH of the mixed solution obtained from the polymerization reaction to 5-7 with a neutralizing agent, preferably controlling the temperature to be below 40 ℃, and then adjusting the PH of the mixed solution after the polymerization reaction.
According to some embodiments of the present invention, the neutralizing agent is added in step S2 in an amount corresponding to the pH of the polycarboxylate water reducer being 7-10.
According to some embodiments of the invention, the neutralizing agent is sodium hydroxide and/or potassium hydroxide.
According to the present invention, the manner of incorporation of the gypsum accelerator is not particularly limited, and may be singly or doubly doped, and preferably is doubly doped.
According to some embodiments of the invention, the preparation method comprises the following specific steps:
(1) a, B preparation of liquid: uniformly mixing an unsaturated carboxylic acid monomer b, an unsaturated sulfonic acid monomer c and deionized water to obtain a solution A; uniformly mixing a chain transfer agent, a reducing agent and deionized water to obtain solution B for later use;
(2) adding deionized water, an unsaturated polyoxyethylene ether monomer a and an unsaturated phenyl monomer d into a reaction kettle, and regulating and controlling the temperature of the reaction kettle to be 40-50 ℃ under stirring to fully dissolve the monomers to obtain a mixed solution;
(3) adding an oxidant into the mixed solution obtained in the step S2 at the reaction temperature of 40-50 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed for 90-180min, finishing dropwise adding the solution B30 min later than the solution A, and after finishing dropwise adding, carrying out curing reaction for 30-90min to obtain a reaction solution;
(4) adding a proper amount of deionized water into the reaction solution obtained in the step (3), cooling to below 40 ℃, adding a proper amount of NaOH solution, adjusting the pH to 5-7, and obtaining gypsum-based polycarboxylate superplasticizer mother liquor with the concentration of 40-60%;
(5) and (5) respectively adding water, the gypsum-based polycarboxylate superplasticizer mother liquor obtained in the step S4, a gypsum excitant and a defoaming agent into a reaction tank, uniformly stirring, adding a neutralizing agent, and adjusting the pH value of the solution to 7-10 to obtain the polycarboxylate superplasticizer.
According to the invention, through molecular structure modification, long side chains of branched polyoxyethylene ether and multifunctional functional groups such as carboxyl, sulfonic group and benzene ring are matched and grafted to synthesize a specific polycarboxylate water reducer taking sulfonic group as a main adsorption group, and the polycarboxylate water reducer is optimized and modified by compounding a gypsum hydration excitant and a defoaming component, so that the polycarboxylate water reducer has the advantages of high water reduction, low air entraining and small influence on gypsum condensation, and is simple in process, green and environment-friendly.
In a third aspect, the present invention provides the use of a polycarboxylate water reducer according to the first aspect of the invention or prepared according to the second aspect of the invention in gypsum plasterboard.
According to some embodiments of the present invention, the solid content of the polycarboxylate superplasticizer is 0.1% to 0.6%, preferably 0.2% to 0.4%.
Compared with the prior art, the invention has the following beneficial effects:
1) the polycarboxylic acid water reducing agent provided by the invention has a water reducing rate far higher than that of efficient water reducing agents such as naphthalene series water reducing agents, melamine water reducing agents and the like, can greatly reduce the dosage of gypsum mixing water, improve the pore structure of a gypsum hardened body, reduce the porosity and obviously improve the flexural strength and compressive strength of the gypsum hardened body.
2) The gypsum-based polycarboxylate superplasticizer mother liquor provided by the invention is modified by adopting a molecular structure, so that sulfonic groups with strong adsorption and dispersion properties on gypsum are used for replacing part of carboxyl, a benzene ring is grafted to change the steric hindrance effect of the structure, the influence of the carboxyl on the hydration retardation of the gypsum is reduced, the high dispersion property of the gypsum is ensured, the auxiliary coagulation promotion of a gypsum excitant and the reduction of the density of pores of gypsum slurry by a defoaming agent are reduced, the production line operation time of the gypsum board is effectively shortened, and the production efficiency is improved.
3) When the polycarboxylate superplasticizer provided by the invention is applied to gypsum board production, no obvious air entraining phenomenon exists, particularly when the polycarboxylate superplasticizer is applied to gypsum board production, starch gelatinization and migration to paper surfaces are not influenced, and the polycarboxylate superplasticizer has good paper surface binding power.
4) The polycarboxylate superplasticizer provided by the invention is green and environment-friendly, does not release harmful substances such as formaldehyde and the like in the using process, and accords with the development direction of green production of gypsum building materials.
Detailed Description
In order that the invention may be more readily understood, the following detailed description of the invention is given in conjunction with the examples which are given for purposes of illustration only and are not to be construed as limiting the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents, instruments or materials used are not indicated by the manufacturer, and are conventional products which are commercially available or obtainable by known production methods.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
HPEG monomers (relative molecular weights 2400, 3000, 4000, 5000) were purchased from Oakk chemical Co., Ltd.
Example 1
1) Dispensing of the dripped liquid A, B: uniformly mixing 20.0g of acrylic acid, 15.5g of 2-acrylamide-2-methylpropanesulfonic acid, 8.0g of sodium allylsulfonate and 30g of deionized water to obtain a dropping liquid A; uniformly mixing 1.0g L-ascorbic acid, 1.0g of mercaptopropionic acid and 54g of deionized water to obtain a dropping liquid B for later use;
2) adding 250g of deionized water, 300g of HPEG monomer (relative molecular mass is 3000) and 2.5g of styrene into a reaction kettle, heating to 50 ℃ under stirring, and dissolving and uniformly mixing to obtain a mixed solution;
3) adding 2.0g of ammonium persulfate into the mixed solution obtained in the step 2) at the reaction temperature of 50 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed, dropwise adding the solution A for 150min, dropwise adding the solution B for 180min, and after dropwise adding, carrying out curing reaction for 45 min;
4) adding 40g of 30% sodium hydroxide solution to adjust the pH value to 5.8 to obtain a polycarboxylic acid water reducing agent mother liquor with the solid content of 50%;
5) 570 parts by mass of water, 400 parts by mass of the 50% polycarboxylate superplasticizer mother liquor obtained in the step 4) and 30 parts by mass of sodium sulfate are sequentially added into a stirring tank, uniformly mixed and dissolved, 0.5 part by mass of polyether modified silicon defoamer and 1.0 part by mass of sodium hydroxide are added, and uniformly mixed, so that the polycarboxylate superplasticizer special for the gypsum plasterboard with the concentration of 23% is obtained.
Example 2
1) Dispensing of the dripped liquid A, B: uniformly mixing 18.0g of acrylic acid, 15.5g of 2-acrylamide-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 35.5g of deionized water to obtain a dropping liquid A; uniformly mixing 1.0g of L-ascorbic acid and 50g of deionized water to serve as a dropping liquid B for later use;
2) adding 350g of deionized water, 400g of HPEG monomer (relative molecular mass: 4000) and 5.2g of sodium styrene sulfonate into a reaction kettle, heating to 45 ℃ under stirring, and dissolving and uniformly mixing;
3) adding 3.0g of 30% hydrogen peroxide solution into the mixed solution obtained in the step 2) at the reaction temperature of 45 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed, dropwise adding the solution A for 120min, dropwise adding the solution B for 150min, and after dropwise adding, carrying out curing reaction for 60 min;
4) adding 35g of 30% sodium hydroxide solution to adjust the pH to 5.6 to obtain a polycarboxylic acid water reducing agent mother liquor with the solid content of 50%;
5) 550 parts by mass of water, 420 parts by mass of the 50% polycarboxylate superplasticizer mother liquor obtained in the step 4), 20 parts by mass of sodium sulfate and 10 parts by mass of calcined alum are sequentially added into a stirring tank, 0.5 part by mass of alkynediol and 1.0 part by mass of potassium hydroxide are added into the stirring tank, and the materials are uniformly mixed to obtain the 24% polycarboxylate superplasticizer special for the gypsum plasterboards.
Example 3
The only difference from example 2 is that the dropping solution A consists of 4.5g of methacrylic acid, 14.5g of acrylic acid, 15.5g of 2-acrylamido-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 36.5g of deionized water.
Example 4
1) Dispensing of the dripped liquid A, B: uniformly mixing 18.0g of acrylic acid, 15.5g of 2-acrylamide-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 30g of deionized water to obtain a dropping liquid A; uniformly mixing 1.2g L-ascorbic acid and 50g of deionized water to serve as a dropping liquid B for later use;
2) adding 450g of deionized water, 500g of HPEG monomer (relative molecular weight of 5000) and 6.25g of sodium styrene sulfonate into a reaction kettle, heating to 45 ℃ under stirring, and dissolving and uniformly mixing;
3) adding 4.0g of 30% hydrogen peroxide solution into the mixed solution obtained in the step 2) at the reaction temperature of 45 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed, dropwise adding the solution A for 150min, dropwise adding the solution B for 180min, and after dropwise adding, carrying out curing reaction for 45 min;
4) adding 45g of 30% potassium hydroxide solution to adjust the pH value to 6.0, and obtaining a polycarboxylic acid water reducing agent mother liquor with the solid content of 50%;
5) 550 parts by mass of water, 420 parts by mass of the 50% polycarboxylate superplasticizer mother liquor obtained in the step 4), 20 parts by mass of potassium sulfate and 10 parts by mass of alum are sequentially added into a stirring tank, uniformly mixed and dissolved, and 0.75 part by mass of tributyl phosphate and 1.25 parts by mass of potassium hydroxide are added and uniformly mixed to obtain the 24% polycarboxylate superplasticizer special for the gypsum plasterboard.
Example 5
1) Dispensing of the dripped liquid A, B: uniformly mixing 18.0g of acrylic acid, 10.35g of 2-acrylamide-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 25g of deionized water to obtain a dropping liquid A; 0.8g L-ascorbic acid and 45g deionized water are uniformly mixed to be used as a dropping liquid B for standby;
2) adding 200g of deionized water, 240g of HPEG monomer (relative molecular mass of 2400) and 5.2g of sodium styrene sulfonate into a reaction kettle, heating to 45 ℃ under stirring, and dissolving and uniformly mixing;
3) adding 3.0g of 30% hydrogen peroxide solution into the mixed solution obtained in the step 2) at the reaction temperature of 45 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed, dropwise adding the solution A for 120min, dropwise adding the solution B for 150min, and after dropwise adding, carrying out curing reaction for 60 min;
4) adding 37.5g of 30% sodium hydroxide solution to adjust the pH to 5.9 to obtain a polycarboxylic acid water reducing agent mother liquor with the solid content of 50%;
5) 550 parts by mass of water, 420 parts by mass of the 50% polycarboxylate superplasticizer mother liquor obtained in the step 4), 20 parts by mass of sodium sulfate and 10 parts by mass of calcined alum are sequentially added into a stirring tank, 0.5 part by mass of alkynediol and 1.0 part by mass of potassium hydroxide are added into the stirring tank, and the materials are uniformly mixed to obtain the 24% polycarboxylate superplasticizer special for the gypsum plasterboards.
Example 6
The only difference from example 2 is that step 2) is: 354g of deionized water, 400g of HPEG monomer (relative molecular weight: 4000) and 9.2g of sodium styrene sulfonate are added into a reaction kettle, and the temperature is raised to 45 ℃ under stirring to dissolve and mix evenly.
Example 7
The only difference from example 2 is that the dropping solution A consists of 18g of acrylic acid, 31.05g of 2-acrylamido-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 51g of deionized water.
Example 8
The only difference from example 2 is that the molar ratio of unsaturated carboxylic acid monomer b to unsaturated polyoxyethylene ether monomer a is 3.5:1, i.e. dropping liquid A is composed of 25.2g of acrylic acid, 15.5g of 2-acrylamide-2-methylpropanesulfonic acid, 11.85g of sodium methallylsulfonate and 42.5g of deionized water.
Comparative example 1
1) Dispensing of the dripped liquid A, B: uniformly mixing 28.8g of acrylic acid and 25g of deionized water to obtain a dropping liquid A; uniformly mixing 1.0g of L-ascorbic acid, 1.5g of mercaptopropionic acid and 50g of deionized water to obtain a dropping liquid B for later use;
2) adding 200g of deionized water and 240g of HPEG monomer (relative molecular weight of 2400) into a reaction kettle, heating to 45 ℃ under stirring, and fully dissolving to obtain a mixed solution;
3) adding 3.0g of 30% hydrogen peroxide solution into the mixed solution obtained in the step 2) at the reaction temperature of 45 ℃, stirring for 5min, then beginning to dropwise add the solution A and the solution B at a constant speed, dropwise adding the solution A for 120min, dropwise adding the solution B for 150min, and after dropwise adding, carrying out curing reaction for 60 min;
4) adding 40g of deionized water, cooling to below 40 ℃, adding 40g of 30% sodium hydroxide solution, adjusting the pH to 5.5, and obtaining a common polycarboxylate superplasticizer mother liquor with the solid content of 45%;
5) adding 520 parts by mass of water, 450 parts by mass of the 45% common polycarboxylic acid water reducer mother liquor obtained in the step 4), 20 parts by mass of sodium sulfate and 10 parts by mass of calcined alum into a stirring tank in sequence, adding 0.5 part by mass of alkynediol and 1.0 part by mass of potassium hydroxide, and uniformly mixing to obtain the common polycarboxylic acid water reducer with the concentration of 23%.
Comparative example 2
The only difference from example 2 is that, without the addition of unsaturated phenyl monomer d, step S2 is: 345g of deionized water and 400g of HPEG monomer (relative molecular mass of 4000) are added into a reaction kettle, and the temperature is raised to 45 ℃ under stirring to dissolve and mix evenly.
Comparative example 3
The only difference from example 2 is that the unsaturated sulfonic acid monomer c is not added, i.e., the dropping liquid A is composed of 18g of acrylic acid and 10g of deionized water; the dropping solution B consisted of 1.0g of 1.0gVC, 2.0g of mercaptopropionic acid, and 50g of deionized water.
Example 9
The only difference is that only 2-acrylamide-2-methylpropanesulfonic acid is used as the unsaturated sulfonic acid monomer, i.e., the dropping liquid A consists of 18g of acrylic acid, 15.5g of 2-acrylamide-2-methylpropanesulfonic acid and 25g of deionized water; the dropping solution B consisted of 1.0g of 1.0gVC, 1.5g of mercaptopropionic acid, and 50g of deionized water.
Example 10
The only difference from example 2 is that only unsaturated olefin sulfonate is used as the unsaturated sulfonic acid monomer, i.e., dropping liquid A is composed of 18g of acrylic acid, 11.85g of sodium methallyl sulfonate, and 20g of deionized water.
Example 11
The difference is that, as in example 2, no gypsum activator and defoamer are added in step 5), that is, 580 parts by mass of water is mixed with 420 parts by mass of polycarboxylate superplasticizer mother liquor to obtain 21% concentration of polycarboxylate superplasticizer special for gypsum plasterboards.
Comparative example 4
Naphthalene series high efficiency water reducing agent (commercially available, Shandong Wanshan chemical Co., Ltd., yellow brown powder, type: FDN-B, content is more than or equal to 92%, sodium sulfate content is less than 10%).
Performance testing
The water consumption and the setting time of the standard consistency are tested in reference to GB/T17669.4-1999 determination of physical properties of the clean slurry of the building gypsum in the examples and the comparative examples, the breaking strength and the absolute dry compressive strength are tested in reference to GB/T17669.3-1999 determination of mechanical properties of the building gypsum in 2h, and the bonding performance of the protective paper and the gypsum core material is tested in reference to GB/T9775-2008 paper plasterboard.
The gypsum is beta hemihydrate gypsum (beta-CaSO)41/2H2O) which meets the requirements of GB/T9776-.
Table 1 results of performance testing
As can be seen from Table 1, under the same mixing amount condition, the polycarboxylic acid water reducing agent special for the paper-surface gypsum boards of examples 1 to 11 prepared by the invention shows a water reducing rate far higher than that of the naphthalene-based high-efficiency water reducing agent of comparative example 4, and as the water consumption for mixing gypsum is greatly reduced, the porosity is reduced, and the void structure of a hardened body is improved, the flexural strength and the compressive strength of a gypsum hardened body are also obviously improved.
Compared with a comparative example 1 prepared by a common polycarboxylic acid water reducing agent, in the examples 1-7, a part of sulfonic groups with strong adsorption and dispersion properties are used for replacing carboxyl groups which have delay influence on gypsum hydration, and the long side chains and the benzene ring structure are combined to increase the steric hindrance effect, so that the influence of the carboxyl groups on gypsum hydration delay is reduced, and the extremely high dispersion property of the water reducing agent is ensured; and the addition of the gypsum excitant further promotes the hydration rate of gypsum slurry, the use of the defoaming agent reduces the pore density of the slurry, overcomes the problems of serious retardation and poor bonding between the protective paper and the gypsum core material when the common polycarboxylate superplasticizer is used for producing the gypsum plaster boards, effectively shortens the production line operation time of the gypsum boards, improves the production efficiency and meets various performance requirements of the production operation of the gypsum plaster boards.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not set any limit to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A polycarboxylate superplasticizer comprises the following raw materials:
unsaturated polyoxyethylene ether monomer a, unsaturated carboxylic acid monomer b, unsaturated sulfonic acid monomer c, unsaturated phenyl monomer d, water, oxidant, reducing agent and optional auxiliary agent selected from chain transfer agent, gypsum excitant and defoaming agent.
2. The polycarboxylate superplasticizer according to claim 1, wherein the molar ratio of the monomer a to the monomer b is 1 (1.5-3), preferably 1 (2-2.7), and/or the molar ratio of the monomer a to the monomer c is 1 (0.5-3), preferably 1 (1-2), and/or the molar ratio of the monomer a to the monomer d is 1 (0.1-0.5), preferably 1 (0.2-0.3).
3. The polycarboxylate water reducer according to claim 1 or 2, characterized in that the unsaturated sulfonic acid monomer c comprises a mixture of 2-acrylamido-2-methylpropanesulfonic acid and an unsaturated alkenyl sulfonate, preferably the unsaturated alkenyl sulfonate is at least one of sodium allyl sulfonate, potassium allyl sulfonate, ammonium allyl sulfonate, sodium methallyl sulfonate, potassium methallyl sulfonate and ammonium methallyl sulfonate,
more preferably, the mass ratio of the 2-acrylamido-2-methylpropanesulfonic acid to the unsaturated olefin sulfonate is (0.5-3):1, preferably (1-2): 1.
4. The polycarboxylate water reducer according to any one of claims 1-3, characterized in that the unsaturated polyoxyethylene ether monomer a is methyl allyl polyoxyethylene ether, and the molecular structural formula of the methyl allyl polyoxyethylene ether is CH2＝C(CH3)-CH2-O-(C2H4O)n-H, wherein n-50-135, preferably n-85-115;
and/or the unsaturated carboxylic acid monomer b is selected from at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid and fumaric acid;
and/or the unsaturated phenyl monomer d is styrene and/or sodium styrene sulfonate;
and/or the oxidant is selected from at least one of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate;
and/or the reducing agent is selected from at least one of L-ascorbic acid, sodium bisulfite, sodium sulfite and sodium hypophosphite.
5. The polycarboxylate water reducer according to any of the claims 1-4, characterized in that the chain transfer agent is selected from at least one of mercaptoethanol, mercaptopropanol, mercaptoacetic acid, mercaptopropionic acid and n-dodecanethiol; and/or the defoaming agent is selected from at least one of polyether defoaming agent, alkynediol, tributyl phosphate and polyether modified silicon defoaming agent; and/or the gypsum excitant is selected from at least one of sodium sulfate, potassium sulfate, aluminum sulfate, ferric sulfate, copper sulfate, sodium oxalate, potassium oxalate, alum, calcined alum, sodium silicate and potassium dichromate.
6. The polycarboxylate water reducer according to any of the claims 1-5, characterized in that the amount of oxidant is 0.3-1.5 wt. -%, based on the total weight of monomers a, b, c, d; and/or the amount of the reducing agent is 0.1 to 0.3 wt%; and/or the amount of chain transfer agent is from 0 to 0.5 wt%;
and/or the weight of the defoaming agent accounts for 0.01-0.2% of the weight of the polycarboxylate water reducer, and/or the weight of the gypsum excitant accounts for 1-5%, preferably 2-3% of the weight of the polycarboxylate water reducer.
7. A preparation method of the polycarboxylic acid water reducer as claimed in any one of claims 1 to 6, characterized by comprising the following steps:
s1, carrying out polymerization reaction on an unsaturated polyoxyethylene ether monomer a, an unsaturated carboxylic acid monomer b, an unsaturated sulfonic acid monomer c and an unsaturated phenyl monomer d in first water in the presence of an oxidant, a reducing agent and an optional chain transfer agent to obtain a polycarboxylic acid water reducer mother liquor;
s2, mixing the polycarboxylate superplasticizer mother liquor obtained in the step S1 with second water and optional gypsum excitant, defoamer and neutralizer to obtain the polycarboxylate superplasticizer;
preferably, the weight ratio of the polycarboxylate superplasticizer mother liquor to the second water is (4-5) to (5-6).
8. The method for preparing a composite material according to claim 7, wherein the step S1 includes:
(1) mixing the first water, the unsaturated polyoxyethylene ether monomer a and the unsaturated phenyl monomer d to obtain a mixed solution;
(2) adding an oxidant into the mixed solution obtained in the step (1), then dropwise adding the solution A and the solution B, carrying out curing reaction to obtain a mother solution of the polycarboxylate superplasticizer,
the solution A is a mixed solution of an unsaturated carboxylic acid monomer B, an unsaturated sulfonic acid monomer c and water, and the solution B is a mixed solution of a reducing agent, a chain transfer agent and water.
9. The method according to claim 7 or 8, wherein the step S1 further comprises adjusting the PH of the mixed solution obtained by the polymerization reaction to 5 to 7 with a neutralizing agent after the polymerization reaction;
and/or the amount of the neutralizing agent in the step S2 is the amount corresponding to the pH value of the polycarboxylate superplasticizer being 7-10;
preferably, the neutralizing agent is sodium hydroxide and/or potassium hydroxide.
10. Use of a polycarboxylate water reducer according to any one of claims 1-6 or prepared according to the preparation method of any one of claims 7-9 in gypsum plasterboard.
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