CN115197353A - Preparation method of low-chroma medium molecular weight polyacrylic acid and salt thereof - Google Patents
Preparation method of low-chroma medium molecular weight polyacrylic acid and salt thereof Download PDFInfo
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- CN115197353A CN115197353A CN202210767402.9A CN202210767402A CN115197353A CN 115197353 A CN115197353 A CN 115197353A CN 202210767402 A CN202210767402 A CN 202210767402A CN 115197353 A CN115197353 A CN 115197353A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F120/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
- C08F120/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F120/04—Acids; Metal salts or ammonium salts thereof
- C08F120/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/44—Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F4/00—Polymerisation catalysts
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
Abstract
The invention relates to a preparation method of medium molecular weight polyacrylic acid with low chroma and a salt thereof, belonging to the technical field of fine chemistry. In an aqueous solution, water-soluble azo hydrochloride is taken as an initiator, hydrogen peroxide is taken as an oxidant, sulfite is taken as a reducing agent and a chain transfer agent to carry out the polymerization of an acrylic monomer, and the method specifically comprises the following steps: adding pure water, part of hydrogen peroxide and part of azo hydrochloride aqueous solution to the bottom of a reaction kettle, introducing nitrogen for protection, heating to 80-85 ℃, simultaneously dropwise adding acrylic acid aqueous solution, the rest of azo hydrochloride aqueous solution and sulfite aqueous solution according to a certain flow, and dropwise adding liquid alkali in the dropwise adding process to keep the pH value of the solution in the reaction kettle at 1-2; and after the dropwise addition is finished, adding another part of hydrogen peroxide, preserving the heat for 1h, cooling, adding liquid alkali, filtering and diluting to obtain polyacrylic acid and a salt water solution thereof. The method can effectively improve the polymerization degree of the molecular weight, reduce free monomers and reduce the chroma; the whole process is simple in reaction, free of three wastes and environment-friendly.
Description
Technical Field
The invention belongs to the technical field of fine chemistry, and particularly relates to a preparation method of medium molecular weight polyacrylic acid (sodium) with low chroma.
Background
Polyacrylic acid (PAA) or a salt thereof is an important water-soluble polymer, has extremely wide application, and is mainly applied to industries such as daily chemical industry, industrial circulating water systems, mining industry, coating, papermaking, textile, building, medical and health and the like.
The different relative molecular masses of polyacrylic acid (sodium) determine its different industrial categories, molecular weight (10) 3 -10 4 ) The polyacrylic acid is a low-relative molecular weight polyelectrolyte and has good scale inhibition and chelating properties, and the salt thereof has good dispersing properties on calcium phosphate and hydrated iron oxide. The water treatment agent is used as a scale inhibitor of calcium carbonate, calcium sulfate and barium sulfate in water treatment, and is used for treating cooling water and boiler water. In the evaporative concentration of liquids in the paper industry and in the mining industry, for preventing scaling. Molecular weight (10) 4 -10 6 ) The slurry prepared from the sodium polyacrylate has high color rendering index, clear patterns and good hand feeling, can improve the good thickening effect by a small amount and reduce the emission pollution.
Tojie et al, university of Central and south, proposed the polymerization reaction of synthesizing acrylic acid monomer in aqueous solution by taking persulfate as an initiator and analyzing and comparing two chain transfer agents, namely isopropanol and sulfite (controllable synthesis and dispersion performance research of polyacrylate). Lisanlan proposes a polymerization reaction in which persulfate is used as an initiator and low-carbon alcohol is used as a chain transfer agent to synthesize a polyacrylic acid monomer in an aqueous solution (synthesis and application of polyacrylic acid and acrylic acid copolymer, guangdong chemical industry, 9 th 2005). Zhang Xiaoyun proposes a redox system in which persulfate is used as an initiator and sulfite is used as a reducing agent to synthesize a polyacrylic acid monomer aqueous solution with medium molecular weight (research on synthesis of medium molecular weight sodium polyacrylate, oil and natural gas chemical industry, 2002,31 (6): 326-328). The water-phase polymerization process is safe and simple, and is the key point of research. However, the above method has certain defects, such as low efficiency of persulfate initiator, solvent recovery and storage problems, high residual amount of polyacrylic acid, low polymerization degree, wide molecular weight distribution, and unstable platinum paleochromaticity of acrylic polymer, which are caused in the later period, and seriously affect the quality of acrylic polymer in the later period.
Disclosure of Invention
The invention aims to provide a preparation method of low-chroma medium-molecular-weight polyacrylic acid and a salt thereof, which can effectively improve the polymerization degree of molecular weight, reduce free monomers and greatly reduce chroma; the whole process has simple reaction, no three wastes and environmental protection.
In order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of low-chroma medium molecular weight polyacrylic acid and its salt, in aqueous solution, using water-soluble azo-type hydrochloride as initiator, hydrogen peroxide as oxidant, sulfite as reducing agent and chain transfer agent to make polymerization of acrylic acid monomer, specifically including the following steps:
adding a certain amount of pure water, part of hydrogen peroxide and part of azo hydrochloride aqueous solution into the bottom of a reaction kettle, introducing nitrogen for protection, heating to 80-85 ℃ under stirring, simultaneously dropwise adding a certain amount of acrylic acid aqueous solution, the rest of azo hydrochloride aqueous solution and sulfite aqueous solution according to a certain flow, and dropwise adding liquid caustic soda in the dropwise adding process to keep the pH value of the solution in the reaction kettle at 1-2;
and (2) after the dropwise addition, adding another part of hydrogen peroxide, keeping the temperature for 1h, cooling, filtering and diluting to obtain a polyacrylic acid aqueous solution with the mass fraction of 30%.
Further, after the dropwise addition in the step (2) is finished, adding another part of hydrogen peroxide, preserving the heat for 1 hour, cooling, adding liquid alkali, filtering and diluting to obtain a sodium polyacrylate aqueous solution with the mass fraction of 30%.
Furthermore, the azo hydrochloride, the acrylic acid and the sulfite are all dripped in the form of aqueous solution, the mass fraction of the azo hydrochloride aqueous solution is 1-3%, the mass fraction of the acrylic acid aqueous solution is 80-90%, and the mass fraction of the sulfite aqueous solution is 1-2%.
Further, the azo hydrochloride is azobisisobutyramidine hydrochloride or azobisisobutyrimidazoline hydrochloride.
Further, in the step (1), the molar ratio of acrylic acid, pure water, azo hydrochloride, sulfite, caustic soda liquid to hydrogen peroxide is 1.
Further, in the step (1), the dropping time of the acrylic acid aqueous solution is 1-3 hours, the dropping time of the hydrogen peroxide is 0.1-0.5 hour, the hydrogen peroxide is added in two parts, the acrylic acid aqueous solution and the hydrogen peroxide are added before reaction and after reaction, and the dropping mode is manual dropping.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a preparation method of medium molecular weight polyacrylic acid and salt thereof with low chroma, which adopts azo hydrochloride as an initiator and hydrogen peroxide as an oxidant to form a redox initiation system with sulfite, utilizes the strong oxidizing property of the hydrogen peroxide to control the chroma of an acrylic polymer in the reaction process, simultaneously controls pH to ensure that the distribution width and the relative molecular weight of the polymer in the reaction process reach the required conditions, and has the advantages of simple whole reaction operation, no three wastes and environmental protection.
Detailed Description
The present invention is described in detail below by way of examples, which are intended to be illustrative only and not to be construed as limiting the scope of the invention, and one skilled in the art will be able to make variations within the scope of the invention based on the disclosure herein, in reagents, catalysts and reaction process conditions. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
The raw materials used in the embodiment of the invention are analytically pure, wherein the mass fraction of the prepared acrylic acid aqueous solution is 80%, the mass fraction of the azo aqueous solution is 3%, the mass fraction of the sulfite aqueous solution is 2%, the mass fraction of the liquid caustic soda is 30%, and the mass fraction of the hydrogen peroxide is 25%.
Example 1
The preparation method of the medium molecular weight polyacrylic acid with low chroma comprises the following steps:
the method comprises the following steps: adding 150g of pure water, 0.5g of hydrogen peroxide and 0.01g of azo initiator into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of azo aqueous solution according to the flow of 17.1g/h, dropwise add acrylic acid aqueous solution according to the flow of 55g/h, dropwise add sulfite aqueous solution according to the flow of 17.2g/h, dropwise add the three aqueous solutions simultaneously, continuously adding 10g of liquid alkali during the process, keeping the pH meter between 1 and 2, and finishing the dropwise addition reaction after 3 hours;
step two: after the dropwise addition, 1g of hydrogen peroxide is added, the temperature is kept for 1h, and 150g of water is added to obtain 508.3g of polyacrylic acid aqueous solution with the mass fraction of 30%.
The product is detected, and the molecular weight is as follows: 75864; molecular weight distribution coefficient: 2.88; residual acrylic monomer amount (based on total monomer mass): 0.08%, platinum-cobalt color: 15.
comparative example 1
The preparation method of the medium molecular weight polyacrylic acid with low chroma of the comparative example comprises the following steps:
the method comprises the following steps: adding 150g of pure water and 0.01g of azo initiator into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of azo aqueous solution according to the flow rate of 17.1g/h, dropwise adding acrylic acid aqueous solution according to the flow rate of 55g/h, dropwise adding sulfite aqueous solution according to the flow rate of 17.2g/h, dropwise adding the three aqueous solutions simultaneously, continuously adding 10g of liquid alkali during the dropwise adding process to keep the pH meter between 1 and 2, and finishing the dropwise adding reaction after 3 hours;
step two: after the dropwise addition, the temperature is kept for 1h, and 150g of water is added to obtain 506.8g of polyacrylic acid aqueous solution with the mass fraction of 30%.
The product is detected to have the following molecular weight: 76781; molecular weight distribution coefficient: 2.85; residual acrylic monomer amount (based on total monomer mass): 0.58%, platinum-cobalt color: 75.
comparative example 2
The preparation method of the medium molecular weight polyacrylic acid with low chroma of the comparative example comprises the following steps:
the method comprises the following steps: adding 150g of pure water and 0.5g of hydrogen peroxide into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of persulfate aqueous solution according to the flow of 17.2g/h, dropwise adding acrylic acid aqueous solution according to the flow of 55g/h, dropwise adding sulfite aqueous solution according to the flow of 17.5g/h, dropwise adding the three aqueous solutions simultaneously, continuously adding 10g of liquid alkali during the dropwise adding process to keep the pH meter between 1 and 2, and finishing the dropwise adding reaction after 3 hours;
step two: after the dropwise addition, 1g of hydrogen peroxide is added, the temperature is kept for 1h, and 150g of water is added to obtain 508.3g of polyacrylic acid aqueous solution with the mass fraction of 30%.
The product is detected to have the following molecular weight: 73241; molecular weight distribution coefficient: 8.61; residual acrylic monomer amount (based on total monomer mass): 0.78%, platinum-cobalt color: 55.
comparative example 3
The preparation method of the medium molecular weight polyacrylic acid with low chroma in the comparative example comprises the following steps:
the method comprises the following steps: adding 150g of pure water into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of sodium persulfate aqueous solution according to the flow of 17.1g/h, dropwise add acrylic acid aqueous solution according to the flow of 55g/h, dropwise add sulfite aqueous solution according to the flow of 17.2g/h, dropwise add the three aqueous solutions simultaneously, continuously adding 10g of liquid alkali during the dropwise add process to keep the pH meter between 1 and 2, and finishing the dropwise add reaction after 3 hours;
step two: after the dropwise addition, the temperature is kept for 1h, and 150g of water is added to obtain 506.8g of polyacrylic acid aqueous solution with the mass fraction of 30%.
The product is detected to have the following molecular weight: 89571 (b); molecular weight distribution coefficient: 3.85; residual acrylic monomer amount (based on total monomer mass): 0.10%, platinum-cobalt color: 49.
example 2
The preparation method of the medium molecular weight sodium polyacrylate with low chroma comprises the following steps:
the method comprises the following steps: adding 150g of pure water, 0.5g of hydrogen peroxide and 0.01g of azo initiator into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of azo aqueous solution according to the flow of 17.1g/h, starting to dropwise add acrylic acid aqueous solution according to the flow of 55g/h, dropwise add sulfite aqueous solution according to the flow of 17.2g/h, dropwise add the three aqueous solutions simultaneously, continuously adding 10g of liquid alkali during the dropwise adding process to keep the pH meter between 1 and 2, and finishing the dropwise adding reaction after 3 hours;
step two: after the dropwise addition, 1g of hydrogen peroxide is added, the temperature is kept for 1h, 450g of water is added, the temperature is reduced to below 50 ℃,200 g of 30 mass percent aqueous alkali and liquid caustic soda are added, and 891.6g of 30 mass percent aqueous solution of sodium polyacrylate is obtained.
The product is detected to have the following molecular weight: 78542; molecular weight distribution coefficient: 2.96; residual acrylic monomer amount (based on total monomer mass): 0.06%, platinum-cobalt color: 9.
comparative example 4
The preparation method of the medium molecular weight sodium polyacrylate with low chroma comprises the following steps:
the method comprises the following steps: adding 150g of pure water, 0.5g of hydrogen peroxide and 0.01g of azo initiator into a four-neck round-bottom flask, inserting a pH meter, starting stirring, heating to 80 ℃, starting to dropwise add 51.5g of azo aqueous solution according to the flow of 17.1g/h, dropwise add acrylic acid aqueous solution according to the flow of 55g/h, dropwise add sulfite aqueous solution according to the flow of 17.2g/h, dropwise add the three aqueous solutions simultaneously, and finishing the dropwise addition reaction after 3.5 h;
step two: after the dropwise addition, 1g of hydrogen peroxide is added, the temperature is kept for 1h, 450g of water is added, the temperature is reduced to below 50 ℃,200 g of 30 mass percent caustic soda liquid is added, and 881.6g of 30 mass percent sodium polyacrylate aqueous solution is obtained.
The product is detected to have the following molecular weight: 11462; molecular weight distribution coefficient: 18.96 parts; residual acrylic monomer amount (based on total monomer mass): 0.09%, platinum-cobalt color: 26.
Claims (6)
1. a preparation method of low-chroma medium molecular weight polyacrylic acid and its salt is characterized by that in the aqueous solution, using water-soluble azo hydrochloride as initiator, hydrogen peroxide as oxidant, sulfite as reducing agent and chain transfer agent to make polymerization of acrylic acid monomer, and concretely includes the following steps:
adding a certain amount of pure water, part of hydrogen peroxide and part of azo hydrochloride aqueous solution into the bottom of a reaction kettle, introducing nitrogen for protection, heating to 80-85 ℃ under stirring, simultaneously dropwise adding a certain amount of acrylic acid aqueous solution, the rest of azo hydrochloride aqueous solution and sulfite aqueous solution according to a certain flow, and dropwise adding liquid caustic soda during the dropwise adding process to keep the pH value of the solution in the reaction kettle at 1-2;
and (2) after the dropwise addition is finished, adding another part of hydrogen peroxide, keeping the temperature for 1h, and cooling, filtering and diluting to obtain a polyacrylic acid aqueous solution with the mass fraction of 30%.
2. The preparation method of the low-chroma medium-molecular-weight polyacrylic acid and the salt thereof as claimed in claim 1, wherein after the dropwise addition in the step (2), another part of hydrogen peroxide is added, and after heat preservation for 1h, the sodium polyacrylate water solution with the mass fraction of 30% is obtained through cooling, adding liquid alkali, filtering and diluting.
3. The method for producing a medium molecular weight polyacrylic acid or a salt thereof having a low chroma according to claim 1, wherein the azo hydrochloride, the acrylic acid, and the sulfite are all added dropwise in the form of an aqueous solution, wherein the mass fraction of the aqueous solution of the azo hydrochloride is 1% to 3%, the mass fraction of the aqueous solution of the acrylic acid is 80% to 90%, and the mass fraction of the aqueous solution of the sulfite is 1% to 2%.
4. The method of claim 1, wherein the azo hydrochloride is azobisisobutyramidine hydrochloride or azobisisobutyrimidazoline hydrochloride.
5. The method for producing low-chroma medium-molecular-weight polyacrylic acid and salts thereof according to claim 1, wherein the molar ratio of acrylic acid, pure water, azo hydrochloride, sulfite, caustic soda lye and hydrogen peroxide in step (1) is 1 to 0.0002 to 0.0005.
6. The method for preparing low-chroma medium-molecular-weight polyacrylic acid and its salt according to claim 1, wherein the dropping time of the acrylic acid aqueous solution in step (1) is 1-3h, the dropping time of the hydrogen peroxide is 0.1-0.5h, the hydrogen peroxide is added in two parts, the addition is performed before the reaction and after the reaction, and the dropping mode is manual dropping.
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| CN202210767402.9A CN115197353A (en) | 2022-07-01 | 2022-07-01 | Preparation method of low-chroma medium molecular weight polyacrylic acid and salt thereof |
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- 2022-07-01 CN CN202210767402.9A patent/CN115197353A/en active Pending
Non-Patent Citations (1)
| Title |
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| 郑书忠等: "《水处理药剂及其应用》", 中国石化出版社, pages: 355 * |
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