CN100487006C - AMPS analog anion copolymer water dispersoid preparation method - Google Patents

Abstract

The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system. It is a multi-stage water dispersion polymerization in the range of pH 1-4. It uses 1-50 mol% of at least one water-soluble anionic vinyl monomer and at least one 50-99 mol% non-ionic vinyl monomer as raw materials; uses hydrophobic monomers as auxiliary comonomers, and the dosage is 1% of the total weight of the monomers. 0.1-5%; use water-soluble anionic polymer as dispersant, chaotropic high and low chaotropic salt as phase separation agent, polyol compound as organic auxiliary dispersant, fumed silica as inorganic auxiliary dispersant , Oxidizing agent-reducing agent-organic azo salt is a compound initiation system (dropping in 2 to 5 times), and the dosage is 0.1 to 5%, 5 to 40%, 0.05 to 5%, and 0.05 to 10% of the total weight of the dispersion system, respectively. % and 0.001~5%; the balance is water. The weight percentage of the water-soluble polymer in the prepared dispersion system is 5-40%, and the relative molecular weight is high and the stability is good.

Description

Preparation method of AMPS type anionic copolymer water dispersion system

technical field

The invention belongs to the cross technical field of polymer copolymer, colloid and interface and chemical technology, more specifically relates to the preparation method of AMPS type anionic copolymer water dispersion system. With the aid of a specific chemical process and the stabilization of a dispersant, the copolymer is uniformly dispersed in a saline solution to form a micron-scale heterogeneous system. It is a kind of coarse colloidal dispersion system and belongs to thermodynamically unstable system.

Background technique

Water-soluble anionic copolymers are widely used in many fields such as oil extraction, water treatment, papermaking, textile, printing and dyeing, coal washing, medicine, sugar refining, building materials, and agriculture.

Traditional water-soluble polymers are dilute aqueous polymer solutions, or polymer hydrogels. With the development of technology, solid powder products have appeared. Publication number is the homogeneous phase polymerization of the aqueous solution of solid powder product disclosed by the Chinese patent of CN85102644A, CN1057057A and CN1168894A. The production unit operations of powder products are many, the production cycle is long, the technical equipment is complex, and there is a contradiction that is difficult to reconcile, the higher the relative molecular weight, the poorer the solubility of the polymer, and it is easy to form a large insoluble gel during the dissolution process. grain. These defects limit the use of powdered polymer products and the development of their polymerization process technology to some extent.

The inverse emulsion polymerization product has good solubility, and the relative molecular weight and degree of hydrolysis can be adjusted freely, but the preparation process needs to consume a large amount of organic solvents, and the obtained product also needs to be demulsified and impurity-removed, and the process is complicated. Moreover, it is inevitable to use organic substances such as mineral oil and surfactant in the emulsion polymerization process, and the addition of the two accounts for about 30% of the product weight. These organic substances are unnecessary for users, and will eventually be discharged to the environment. Therefore, while the cost is increased, it also causes secondary pollution to the environment.

Water dispersion polymerization technology is one of the research hotspots in the field of international water-soluble polymers. The principle of the reaction is: the monomer is completely dissolved in the brine solution, but the polymer particles are insoluble in the brine solution; as the polymerization reaction proceeds, the polymer particles gradually increase, and when the relative molecular mass increases to a certain critical When the value is high, it will precipitate due to the salting-out effect of inorganic salts, causing the product to separate from the solution; at the same time, with the help of the dispersion and stabilization of various organic or inorganic dispersants, the precipitated polymer particles are evenly dispersed in the brine solution to form Micron-scale heterogeneous systems. This method retains the advantages of solution polymerization, the heat of polymerization is easy to dissipate, the viscosity of the system is small, and the rheological properties of the product are excellent; the polymerization process is easy to operate, the relative molecular mass distribution of the polymer is narrow, and the residual monomers are basically retained in the solvent, which is beneficial High-purity polymer products are obtained. Compared with the other three polymerization technologies of water-soluble polymers, water dispersion polymerization technology is an environmentally friendly polymer chemical technology with great development potential.

In recent years, researchers in western countries have successively studied the preparation process of polymer water dispersion systems, covering the fields of anionic, cationic and zwitterionic water-dispersed polymers. In 2001, Japanese Matsushima Shangji and others used N-vinyl formamide and acrylic acid derivatives as monomer raw materials, ammonium chloride as phase separation agent, and water-soluble azo compound as initiator, and prepared by one-time feeding An anionic hydrophobic water dispersion system is developed, and the diameter of the copolymer is several microns. However, American scholar Connors and others use acrylamide, acryloyloxyethyltrimethylammonium chloride and acryloyloxyethylaminobenzylammonium chloride as raw material monomers, and use ammonium sulfate as a phase separation agent to denature Starch and guar gum were used as dispersants, and the cationic polymer water dispersion system was prepared by one-time feeding under high-speed stirring. In the above two examples, due to the limitation of one-time feeding method, the preparation stability and storage stability of the obtained product are relatively poor, the particle size distribution of the polymer is uneven, and the storage period is short.

U.S. Patent No. 3,658,772 discloses that sodium acrylate, acrylamide and dimethylaminoethyl methacrylate, etc. , a polymer dispersion with good fluidity was obtained. It is worth noting that the pH value reported in the patent should be adjusted to 1-3.2 during polymerization, and if the pH value is increased to 4 or higher, a non-flowable gel product will be produced. In US Pat. No. 3,493,500, a stable dispersion cannot be obtained when the pH value is higher than 4.

The above few examples basically represent the current research level of water-dispersed polymers. The limitation of one-time feeding and the selection of dispersants make these products have stability problems to varying degrees.

Contents of the invention

The purpose of the present invention is just to overcome above-mentioned shortcoming and deficiency, a kind of preparation method of AMPS type anionic copolymer aqueous dispersion system is provided. It uses AMPS monomers and acrylamide monomers as raw materials, adds water-soluble anionic polymers as dispersants, and adds various organic auxiliary dispersants and inorganic auxiliary dispersants at the same time. Composite initiation system, using multi-stage water dispersion polymerization technology in saline solution, can prepare polymer water dispersion system with high relative molecular weight and good stability.

This method uses water-soluble anionic polymer, polyol compound and fumed silica as composite dispersant, uses oxidation-reduction-organic azo salt as composite initiation system, and adopts multi-stage polymerization technology to obtain a stable polymer water dispersion system. It overcomes the problem of product stability caused by one-time feeding and the use of a single dispersant, and adopts a composite initiation system, which is easy to obtain a copolymer product with a high relative molecular weight.

In order to achieve the above object, the present invention uses a multi-stage water dispersion polymerization method to polymerize in the range of pH value 1 to 4 according to the following material ratio:

a. Using 1-50 mol% of at least one water-soluble anionic vinyl monomer and at least one 50-99 mol% non-ionic vinyl monomer as raw materials;

b. Use hydrophobic monomers as auxiliary comonomers in an amount of 0.1 to 5% of the total weight of the above monomers;

c. Using water-soluble anionic polymer as dispersant, the dosage is 0.1-5% of the total weight of the dispersion system;

d. Using at least one chaotropic salt and at least one chaotropic salt as a phase separation agent, the amount is 5 to 40% of the total weight of the dispersion;

e. Polyol compounds are used as organic auxiliary dispersants in an amount of 0.05-5% of the total weight of the dispersion system;

f. Using fumed silica as an auxiliary inorganic dispersant, the dosage is 0.05-10% of the total weight of the dispersion system;

g. Take the oxidizing agent-reducing agent-organic azo salt as the compound initiation system, the dosage is 0.001-5% of the total weight of the monomer, and add it dropwise in 2-5 times;

h. The balance is water;

The weight percentage of the water-soluble polymer in the prepared dispersion system is 5-40%.

The preparation process is as follows: put some monomers, salts, dispersants and other additives into the reactor, adjust the pH value of the system, stir and raise the temperature, and add part of the initiator dropwise in nitrogen atmosphere. After reacting for a period of time, adopt multi-stage polymerization, add the remaining monomers and initiators in batches, react at constant temperature for 6-8 hours, and finally cool down to room temperature and discharge. The final product is milky white smooth liquid with good fluidity and stability. The relative molecular mass of the dispersed polymer of the present invention is usually in the range of 2,000,000 to 20,000,000, and the Brookfield viscosity at 20°C is less than 2,000mPa·s.

The anionic vinyl monomers used in the present invention can be selected from a wide range. The monomers used should have vinyl or propenyl functionality and contain carboxyl, sulfonate, phosphate, or other anionic groups, as well as water-soluble alkali metal, alkaline earth metal, or ammonium salts of the foregoing.

Suitable water-soluble anionic vinyl monomers are selected from the group consisting of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-acrylamido-3-methylbutyric acid, maleic acid or styrenesulfonic acid, and the water-soluble alkali metal, alkaline earth metal or ammonium salts of the above substances.

The nonionic monomer used in the present invention can be any uncharged vinyl monomer. Suitable monomers include acrylamide, methacrylamide, N-isopropylacrylamide, N-t-butylacrylamide or N-methacrylamide.

The amount of monomer used in the aqueous copolymer dispersion system accounts for 5-40% of the weight of the dispersion, generally 10-40%, preferably 15-30%.

Non-ionic vinyl monomers and anionic vinyl monomers can be mixed in any proportion, and the properties of the prepared water-dispersed polymers are also different according to the composition ratio of various monomers.

The present invention selects hydrophobic monomers as auxiliary comonomers. The hydrophobic monomer is selected from C ₂ -C ₃₂ alkyl esters, or compounds with rigid rings. Suitable hydrophobic monomers include C ₁ -C ₈ dialkyl ester monomers of itaconic acid: dimethyl itaconate, dibutyl itaconate or dioctyl itaconate; or acrylic acid or methacrylic acid C ₁ ~C ₃₂ alkyl ester monomers: ethyl acrylate, butyl acrylate, octadecyl acrylate or octadecyl methacrylate; or diene monomers: butadiene, chloroprene; Or sodium p-styrenesulfonate, N-vinylpyrrolidone. In the present invention, the amount of the hydrophobic monomer accounts for 0.1-5% of the total weight of the monomer, generally 0.1-4%, preferably 0.1-3%.

Most hydrophobic monomers have longer hydrophobic chain segments or rigid ring units. This can improve the rigidity and regularity of the polymer molecular chain from a microscopic level; moreover, polymers containing hydrophobic groups are more likely to precipitate in saline solution than polymers without hydrophobic groups. From a macro perspective, a small amount of hydrophobic monomers participate in the polymerization, which helps to improve the preparation and storage stability of the water dispersion system. The choice of polymer dispersant depends on the type of water-dispersed polymer and the process conditions of water-dispersed polymerization. A good dispersant should have strong adsorption on the surface of polymer particles and be soluble in the dispersion medium.

In the absence of any dispersant, the polymer particles may dissolve within a short time after formation, and the prepared polymer dispersion will produce a paste like a thin slurry, which will thicken to form a gel in a relatively short time piece. However, as long as a small amount of a suitable dispersant is added to the polymer, stable dispersed phase particles are produced. The particle stabilization phenomenon in dispersion polymerization is characterized by "steric stabilization".

The dispersant is selected from homopolymers or copolymers of 2-acrylamido-2-methylpropanesulfonic acid, and the dispersant contains at least 10% of 2-acrylamido-2-methylpropanesulfonic acid in molar concentration , the polymer can be prepared by conventional aqueous solution polymerization techniques.

The intrinsic viscosity of the polymer dispersant in 1M NaCl is 0.1-12dL/g, generally 0.3-10.0dL/g, preferably 0.5-7.0dL/g.

The amount of dispersant used in the present invention accounts for 0.1-5% of the weight of the entire dispersion, preferably 0.25-1.5%, more preferably 0.4-1.25%. If the amount of dispersant is too small, it will not have the proper stabilizing effect on the polymer, and the generated polymer particles will be dissolved in water, the viscosity of the aqueous solution will increase, and finally the polymer gel is obtained instead of the water dispersion system; and When its amount is too large, the stabilizing effect of the dispersant will not be significantly enhanced, but will lead to a decrease in the relative molecular weight of the polymer.

In the present invention, the polyhydroxy compound is added in the reaction system as an auxiliary organic dispersant, so that the precipitation process of the polymer particles can be carried out smoothly.

The organic auxiliary dispersant selected in the present invention is polyhydric alcohol, including polyfunctional ethanol: glycerin or polyethylene glycol, or polysaccharides: modified tapioca starch, pullulan, dextran or methyl ester cellulose.

The role of the organic auxiliary dispersant is to act as a colloidal protective agent in the initial stage of the polymerization reaction. When in use, the amount of the organic auxiliary dispersant accounts for 0.05-5% of the total weight of the dispersion system, preferably 0.05-4%, preferably 0.05-2%.

The present invention uses fumed silica as an auxiliary inorganic dispersant. In the water dispersion system, due to the small particle size and high surface energy of fumed silica, they can be adsorbed on the surface of polymer particles and form a surface layer on the surface of the particles to improve the hydrophobic dispersion performance of the polymer, so it can be used as an inorganic dispersion agent use. The addition of fumed silica should not be too much, because too much addition will cause the system to have too strong thixotropy, resulting in insufficient edge shear force during dispersion, and it will be jelly-like, which will affect the dispersion effect. The amount of fumed silica used in the present invention is selected as 0.01-10%, preferably 0.05-7%, and the optimal range is 0.05-5%.

Phase separation agents suitable for use in the present invention include at least one chaotropic salt and at least one chaotropic salt. The chaotropic salt selected in the present invention includes inorganic salts: sulfate, phosphate, hydrogen phosphate or fluoride, or organic salts: citrate, acetate, tartrate. The cation will also have a certain influence on the solubility of the polymer. It can be ammonium ions or alkali metal ions and alkaline earth metal ions, such as lithium, sodium, potassium, magnesium, calcium ions, etc. However, anionic copolymers tend to form complexes with divalent metal ions (such as Ca ²⁺ ), so monovalent cation salts are usually used. The chaotropic salt selected in the present invention comprises thiocyanate, perchlorate, chlorate, bromate or nitrate, wherein preferred sodium thiocyanate, ammonium thiocyanate, potassium thiocyanate, perchlorate sodium chlorate or sodium chlorate. If the concentration of the phase separation agent is too low, it is not conducive to the sedimentation of polymer particles, while if it is too high, it will cause difficulty in dissolution, and it does not meet the economic requirements. The amount of the phase separation agent is 5-40% of the total weight of the dispersion, preferably 5-30%, more preferably 8-25%.

The invention adopts a compound initiation system composed of oxidation-reduction-organic azo salt. Wherein the oxidizing agent is ammonium persulfate, potassium persulfate or hydrogen peroxide, the reducing agent is sodium sulfite, sodium bisulfite, ferrous sulfate, triethoxyamine or tetramethylethylenediamine, and the organic azo salt is 2,2 - Azobis(2-amididazolinylpropane) dihydrochloride (V-044), 2,2-azobis(2-amidinopropane) dihydrochloride (ABAH) or 2,2-azobis Isobutyronitrile (AIBN). The present invention preferably adopts a composite initiation system composed of potassium persulfate, sodium bisulfite and 2,2-azobis(2-imidazolinyl propane) dihydrochloride (V-044). The amount of the composite initiator added can vary according to the reaction temperature, but the amount used is generally 0.001-5% of the total weight of the monomers.

In addition to the above-mentioned substances, in the preparation process of the present invention, other additives can also be used, chelating agents are used to remove impurity metal ions, so as not to interfere with the activity of the free radical catalyst used, and chain transfer agents for adjusting the relative molecular mass wait.

Task of the present invention is accomplished like this.

The present invention adopts AMPS type monomer and acrylamide type monomer as raw materials, adds water-soluble polymer as dispersant, adds organic type auxiliary dispersant and inorganic type auxiliary dispersant at the same time, uses oxidizing agent-reducing agent-organic azo salt as Composite initiation system, using multi-stage water dispersion polymerization technology in saline solution to prepare a copolymer water dispersion system with high relative molecular weight and good stability. Can be widely promoted and applied.

Detailed ways

The following examples further illustrate the present invention in detail, but these examples do not limit the scope of the present invention.

Example 1. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system. It is polymerized in the range of pH 1-4, according to the following material ratio, using multi-stage water dispersion polymerization method:

a. Using 1-50 mol% of at least one water-soluble anionic vinyl monomer and at least one 50-99 mol% non-ionic vinyl monomer as raw materials;

b. Use hydrophobic monomers as auxiliary comonomers in an amount of 5% of the total weight of the above-mentioned monomers;

c. Using water-soluble anionic polymer as dispersant, the consumption is 3% of the total weight of the dispersion system;

d. Using at least one chaotropic salt and at least one chaotropic salt as a phase separation agent, the amount is 5% of the total weight of the dispersion;

e. Use polyalcohol compounds as organic auxiliary dispersants in an amount of 0.2% of the total weight of the dispersion system;

f. Using fumed silica as an auxiliary inorganic dispersant, the dosage is 5% of the total weight of the dispersion system;

g. Take the oxidizing agent-reducing agent-organic azo salt as the composite initiation system, and the dosage of the composite initiator is 5% of the total weight of the monomers, which is added dropwise in 3 times;

h. The balance is water;

The weight percentage of the water-soluble polymer in the prepared dispersion system is 5-40%.

Its preparation process is as follows: first put part of the monomer, salt, dispersant and other additives into the reactor, adjust the pH value of the system, stir and heat up, add part of the initiator dropwise in a nitrogen atmosphere; after a period of reaction, Using multi-stage polymerization, add the remaining monomer and initiator in batches, then react at constant temperature for 7 hours, and finally cool down to room temperature and discharge.

Said water-soluble anionic vinyl monomer is acrylic acid.

The nonionic vinyl monomer is N-methacrylamide.

The hydrophobic monomer is a C ₂ -C ₃₂ alkyl ester or a compound with a rigid ring, and it is a C ₁ -C ₈ dialkyl ester monomer of itaconic acid.

The dispersant is selected from homopolymers or copolymers of 2-acrylamido-2-methylpropanesulfonic acid, and the dispersant contains at least 10% of 2-acrylamido-2-methylpropanesulfonic acid in molar concentration .

The organic auxiliary dispersant is polyhydric alcohol, including polyfunctional alcohol: glycerin or polyethylene glycol, and the inorganic auxiliary dispersant is fumed silica.

The phase separation agent comprises at least one chaotropic salt and at least one chaotropic salt, wherein said chaotropic salt is sulfate, and said chaotropic salt is thiocyanate.

Oxidant is ammonium persulfate in the oxidizing agent-reductive agent-organic azo salt composite initiation system, and reducing agent is sodium sulfite, and organic azo salt is 2,2-azobis (2-imidazolinyl propane) dihydrochloride (V- 044).

Example 2. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system. It is polymerized in the range of pH 1-4, according to the following material ratio, using multi-stage water dispersion polymerization method:

a. Using 1-50 mol% of at least one water-soluble anionic vinyl monomer and at least one 50-99 mol% non-ionic vinyl monomer as raw materials;

b. Use hydrophobic monomers as auxiliary comonomers in an amount of 0.1% of the total weight of the above-mentioned monomers;

c. Using water-soluble anionic polymer as dispersant, the consumption is 5% of the total weight of the dispersion system;

d. Using at least one chaotropic salt and at least one chaotropic salt as a phase separation agent, the amount is 30% of the total weight of the dispersion;

e. Use polyalcohol compounds as organic auxiliary dispersants, and the dosage is 2% of the total weight of the dispersion system;

f. Using fumed silica as an auxiliary inorganic dispersant, the amount is 4% of the total weight of the dispersion system;

g. Take the oxidizing agent-reducing agent-organic azo salt as the composite initiation system, and the dosage of the composite initiator is 0.001% of the total weight of the monomer, and add it dropwise in 2 times;

h. The balance is water;

The weight percentage of the water-soluble polymer in the prepared dispersion system is 5-40%.

Its preparation process is as follows: first put part of the monomer, salt, dispersant and other additives into the reactor, adjust the pH value of the system, stir and heat up, add part of the initiator dropwise in a nitrogen atmosphere; after a period of reaction, Using multi-stage polymerization, add the remaining monomer and initiator in batches, then react at constant temperature for 8 hours, and finally drop to room temperature and discharge.

The water-soluble anionic vinyl monomer is 2-acrylamido-2-methylpropanesulfonic acid.

The nonionic vinyl monomer is methacrylamide.

The hydrophobic monomer is selected from C ₂ -C ₃₂ alkyl esters or compounds with rigid rings, and is a C ₁ -C ₈ dialkyl ester monomer of itaconic acid.

The dispersant is selected from homopolymers or copolymers of 2-acrylamide-2-methylpropanesulfonic acid. The intrinsic viscosity of the dispersant in 1M NaCl is 0.5-7.0dL/g, and its dosage accounts for the weight percentage of the dispersion 0.1-5% of the total.

The said organic auxiliary dispersant polyol is polyethylene glycol, and the inorganic auxiliary dispersant is fumed silica.

The phase separation agent comprises at least one chaotropic salt and at least one chaotropic salt, wherein said chaotropic salt is phosphate, and said chaotropic salt is nitrate.

The oxidizing agent in the oxidizing agent-reducing agent-organic azo salt composite initiation system is potassium persulfate, the reducing agent is sodium bisulfite, and the organic azo salt is 2,2-azobis(2-amidinopropane) dihydrochloride salt (ABAH).

Example 3. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system. It is polymerized in the range of pH 1-4, according to the following material ratio, using multi-stage water dispersion polymerization method:

a. Using 1-50 mol% of at least one water-soluble anionic vinyl monomer and at least one 50-99 mol% non-ionic vinyl monomer as raw materials;

b. Use hydrophobic monomers as auxiliary comonomers in an amount of 3% of the total weight of the above-mentioned monomers;

c. Use a water-soluble anionic polymer as a dispersant, and the dosage is 0.1% of the total weight of the dispersion system;

d. Using at least one chaotropic salt and at least one chaotropic salt as a phase separation agent, the consumption is 40% of the total weight of the dispersion;

e. Polyhydric alcohol compounds are used as organic auxiliary dispersants, and the dosage is 0.05% of the total weight of the dispersion system;

f. Using fumed silica as an auxiliary inorganic dispersant, the dosage is 0.05% of the total weight of the dispersion system;

g. Take the oxidizing agent-reductant-organic azo salt as the composite initiation system, and the composite initiator consumption is 4% of the total weight of the monomer, which is added dropwise in 5 times;

h. The balance is water;

The weight percentage of the water-soluble polymer in the prepared dispersion system is 5-40%. Its preparation process is as follows: first put part of the monomer, salt, dispersant and other additives into the reactor, adjust the pH value of the system, stir and heat up, add part of the initiator dropwise in a nitrogen atmosphere; after a period of reaction, Using multi-stage polymerization, add the remaining monomer and initiator in batches, then react at constant temperature for 6 hours, and finally cool down to room temperature and discharge.

The water-soluble anionic monomer is 3-acrylamido-3-methylbutyric acid.

The nonionic water-soluble monomers are N-isopropylacrylamide, N-methacrylamide and the like.

The hydrophobic monomer is selected from C ₂ -C ₃₂ alkyl esters or compounds with rigid rings, such as sodium p-styrenesulfonate and N-vinylpyrrolidone.

The dispersant is selected from homopolymers or copolymers of 2-acrylamido-2-methylpropanesulfonic acid, and the dispersant contains at least 10% of 2-acrylamido-2-methylpropanesulfonic acid in molar concentration .

The organic auxiliary dispersant polyol is polysaccharide: modified tapioca starch, and the inorganic auxiliary dispersant is fumed silicon dioxide.

The phase separation agent comprises at least one chaotropic salt and at least one chaotropic salt, the said chaotropic salt is hydrogen phosphate, and the chaotropic salt is bromate.

The oxidizing agent in the oxidizing agent-reducing agent-organic azo salt composite initiation system is hydrogen peroxide, the reducing agent is ferrous sulfate, and the organic azo salt is 2,2-azobis(2-amidinopropane) dihydrochloride (ABAH).

Example 4. This example illustrates the preparation of the polymeric dispersants used in the present invention.

200g of 2-acrylamido-2-methylpropanesulfonic acid, 1466g of deionized water and 0.2g of EDTA·2Na were successively put into a 2L reactor. The mixture was stirred and heated to 45°C, and 1000 cc/min of nitrogen gas was blown to fully remove oxygen. After adding 0.1g of V-044, the polymerization reaction starts after 15 minutes, and the viscosity of the solution increases. After stirring for 4-5 hours, the homopolymer of 2-acrylamido-2-methylpropanesulfonic acid is obtained. The intrinsic viscosity of the polymer measured in 1M NaCl is 1-4dL/g.

Example 5. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

It is in the reactor with agitator, thermometer and condenser, add 419.08g deionized water, 105.00g sodium sulfate, 135.00g ammonium sulfate, 5.00g potassium thiocyanate, 60g 2-acrylamido-2- Methylpropanesulfonic acid homopolymer (12%, intrinsic viscosity 3.76dL/g in 1M NaCl), 62.7g acrylamide (AM), 27.2g 2-acrylamido-2-methylpropanesulfonic acid (AMPS) , 6.00g butyl acrylate (BA), 2.70g 50% NaOH solution, 0.15g EDTA·2Na and 5.00g fumed silicon dioxide, 8.00g modified tapioca starch, stir and feed nitrogen at the same time. The solution was heated to 45°C, and 1.92g K ₂ S ₂ O ₈ , 4.8g NaHSO ₃ , and 1.00g 4% V-044 solution were added. After 15 min the reaction started and a milky dispersion was formed. After keeping the temperature at 45°C for 2 hours, gradually add 125.00g of deionized water, 20.91g of acrylamide, 9.09g of 2-acrylamido-2-methylpropanesulfonic acid, 0.9g of 50% NaOH solution and 0.05g of EDTA dropwise within the next 1.5h • 2Na. The reaction was continued at 50° C. for 1 h, and then 0.25 g of 4% V-044 solution was added. The temperature was raised to 60° C., 0.25 g of 4% V-044 solution was added, and the reaction was continued for 4 hours, then cooled to room temperature and discharged.

The prepared AM/BA/AMPS terpolymer dispersion had a brookfield viscosity of 430 mPa·s, a pH of 3.40, a relative molecular mass of 562.6×10 ⁴ , an active substance content of 12%, and an anionicity of 30%.

Example 6. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

It is in the reactor with agitator, thermometer and condenser, add 419.08g deionized water, 105.00g sodium sulfate, 135.00g ammonium sulfate, 5.00g potassium thiocyanate, 60g 2-acrylamido-2- Methylpropanesulfonic acid homopolymer (12% concentration, intrinsic viscosity in 1M NaCl is 3.76dL/g), 59.32g acrylamide (AM), 30.58g 2-acrylamido-2-methylpropanesulfonic acid (AMPS ), 6.00g of butyl acrylate (BA), 2.70g of 50% NaOH solution, 0.15g of EDTA·2Na, 5.00g of fumed silica, and 8.00g of modified tapioca starch were stirred and fed into nitrogen gas at the same time. The solution was heated to 45° C., and 1.92 g of Na ₂ S ₂ O ₈ , 4.8 g _{of Na 2} SO ₃ , and 1.00 g of 4% V-044 solution were added. After 15 min the reaction started and a milky dispersion was formed. After keeping the temperature at 45°C for 2 hours, gradually add 125.00g of deionized water, 19.78g of acrylamide, 10.22g of 2-acrylamido-2-methylpropanesulfonic acid, 0.9g of 50% NaOH solution and 0.05g of EDTA dropwise within the next 1.5h • 2Na. The reaction was continued at 50° C. for 1 h, and then 0.25 g of 4% V-044 solution was added. Raise the temperature to 60°C, add 0.25g of 4% V-044 solution, continue stirring for 4h, then cool down to room temperature and discharge.

The prepared AM/BA/AMPS terpolymer dispersion had a brookfield viscosity of 380 mPa·s, a pH of 3.40, a relative molecular mass of 693.6×10 ⁴ , an active substance content of 12%, and an anionicity of 15%.

Example 7. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

In the reactor with stirrer, thermometer and condenser, add 259.26g deionized water, 105.00g sodium sulfate, 135.00g ammonium sulfate, 5.00g potassium thiocyanate, 120g 2-acrylamido-2-methyl Propanesulfonic acid homopolymer (12%, intrinsic viscosity in 1M NaCl is 3.76dL/g), 125.4g acrylamide (AM), 54.4g 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 12.00 g butyl acrylate (BA), 5.40 g 50% NaOH solution, 0.3 g EDTA·2Na, 5.00 g fumed silica, 8.00 g modified tapioca starch, stir and feed nitrogen at the same time. The solution was heated to 45° C., and 3.84 g of Na ₂ S ₂ O ₈ , 9.6 g _{of Na 2} SO ₃ , and 2.00 g of 4% V-044 solution were added. After 15 min the reaction started and a milky dispersion was formed. After keeping the temperature at 45°C for 2 hours, gradually add 90.00g of deionized water, 40.82g of acrylamide, 18.08g of 2-acrylamido-2-methylpropanesulfonic acid, 0.8g of 50% NaOH solution and 0.10g of EDTA dropwise within the next 1.5h • 2Na. The reaction was continued at 50° C. for 1 h, and then 0.50 g of 4% V-044 solution was added. Raise the temperature to 60°C, add 0.50g of 4% V-044 solution, continue to stir for 4h, then cool down to room temperature and discharge.

The prepared AM/BA/AMPS terpolymer dispersion had a brookfield viscosity of 540 mPa·s, a pH of 3.40, a relative molecular mass of 623.6×10 ⁴ , an active substance content of 24%, and an anionicity of 30%.

Comparative Example 1: In the same manner as in Example 5, no fumed silica and modified tapioca starch were used. The prepared AM/BA/AMPS terpolymer dispersion had a Brookfield viscosity of 390 mPa·s, a relative molecular mass of 572.3×10 ⁴ , an active substance content of 12%, and an anionicity of 30%. There are a lot of large particles in the obtained white dispersion, and stratification occurs after standing for 60 days.

Comparative example 2: The composite initiation system of K ₂ S ₂ O ₈ , NaHSO ₃ , and V-044 was replaced by V-044, and the three additions were unchanged. The add-on of other components and operation, polymerization condition are the same as embodiment 5. The prepared AM/BA/AMPS terpolymer dispersion had a Brookfield viscosity of 501 mPa·s, a relative molecular mass of 430.5×10 ⁴ , an active substance content of 12%, and an anionicity of 30%.

Example 8. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

Its sodium sulfate consumption is reduced to 78.75g, and ammonium sulfate consumption is reduced to 101.25g, and meanwhile, the first water addition increases to 560g. Thus, the amount of phase separation agent accounted for 18% of the total weight of the aqueous dispersion. The addition, operation and polymerization conditions of monomer, dispersant and other components are the same as in Example 5.

The prepared AM/BA/AMPS terpolymer dispersion had a Brookfield viscosity of 312 mPa·s, a relative molecular mass of 534.6×10 ⁴ , an active substance content of 18%, and an anionicity of 30%.

Example 9. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

This example illustrates the importance of inorganic salts in the preparation of water-dispersed polymers.

Sodium sulfate, ammonium sulfate consumption is reduced to 0g. The amount of water added for the first time was increased to 740g. The addition, operation and polymerization conditions of monomer, dispersant and other components are the same as in Example 5.

As a result, the product agglomerates into lumps during the stirring polymerization.

Example 10. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

Increase the amount of dispersant 2-acrylamide-2-methylpropanesulfonic acid homopolymer to 80g, and reduce the amount of water added for the first time to 480g. The addition, operation and polymerization conditions of the monomer, phase separation agent and other components are the same as in Example 5.

The prepared AM/BA/AMPS terpolymer dispersion had a Brookfield viscosity of 689 mPa·s, a relative molecular mass of 596.3×10 ⁴ , an active substance content of 12%, and an anionicity of 30%.

Example 11. The invention discloses a preparation method of an AMPS-type anionic copolymer water dispersion system.

This practice illustrates the importance of dispersants in the preparation of water-dispersible polymers.

The amount of dispersant 2-acrylamide-2-methylpropanesulfonic acid homopolymer is 0g, and the amount of water added for the first time is increased to 560g. The addition, operation and polymerization conditions of the monomer, phase separation agent and other components are the same as in Example 5. As a result, under the condition that there is no dispersant, a thin slurry-like paste is produced, which thickens to form a glue block in a relatively short time.

Examples 1 to 11 use AMPS monomers and acrylamide monomers as raw materials, add water-soluble anionic polymers as dispersants, and add various organic and inorganic auxiliary additives at the same time, with oxidants-reductants-organic azo salts as Composite initiation system, using multi-stage water dispersion polymerization technology in saline solution, can prepare polymer water dispersion system with high relative molecular weight and good stability. This method can be widely applied.

Claims (5)

1. the preparation method of an anionic copolymer aqueous dispersion is characterized in that it is in the pH value is 1～4 scope, by following material proportion, adopts multistage aqueous dispersion polymerization method polymerization:

A. be raw material with at least a water soluble anion vinyl monomer of 1～50mol% and the nonionic ethylene base monomer of at least a 50～99mol%;

B. make auxiliary comonomer with hydrophobic monomer, consumption is 0.1～5% of an above-mentioned total monomer weight;

C. dispersant dosage is 0.1～5% of a dispersion system gross weight;

D. with at least a chaotropic salt with at least aly make phase separation agent from the low salt of liquid sequence, consumption is 5～40% of a dispersion system gross weight;

E. make organic class auxiliary dispersants with multicomponent alcoholics compound, consumption is 0.05～5% of a dispersion system gross weight;

F. make the mineral-type auxiliary dispersants with aerosil, consumption is 0.05～10% of a dispersion system gross weight;

G. be composite initiation system with oxygenant-reductive agent-organic diazo salt, consumption is 0.001～5% of a total monomer weight, divides 2～5 droppings;

H. surplus is a water;

The weight percent of water-soluble polymers is 5～40% in the dispersion system of preparation;

Wherein the water soluble anion vinyl monomer is selected from vinylformic acid, methacrylic acid, 2-acrylamido-2-methyl propane sulfonic acid, 3-acrylamido-3-methyl butanol acid, maleic acid or styrene sulfonic acid;

Nonionic ethylene base monomer is acrylamide, Methacrylamide, N-N-isopropylacrylamide or N methacrylamide;

Hydrophobic monomer is meant dimethyl itaconate, dibutyl itaconate, dioctyl itaconate, ethyl propenoate, butyl acrylate, vinylformic acid stearyl, methacrylic acid stearyl, divinyl, chloroprene, sodium p styrene sulfonate or N-V-Pyrol RC;

Dispersion agent is selected from the homopolymer or the multipolymer of 2-acrylamido-2-methyl propane sulfonic acid.

2. according to the preparation method of the described anionic copolymer aqueous dispersion of claim 1, it is characterized in that said multicomponent alcoholics compound is multifunctional ethanol or polysaccharide as organic class auxiliary dispersants, multifunctional ethanol is glycerine or polyoxyethylene glycol, and polysaccharide is modified tapioca starch, amylopectin, dextran or methoxycarbonyl Mierocrystalline cellulose.

3. according to the preparation method of the described anionic copolymer aqueous dispersion of claim 1, it is characterized in that said is vitriol, phosphoric acid salt, hydrophosphate, Citrate trianion, acetate or tartrate from the low salt of liquid sequence, and chaotropic salt is thiocyanate-, perchlorate, oxymuriate, Australia's hydrochlorate or nitrate.

4. according to the preparation method of the described anionic copolymer aqueous dispersion of claim 1, it is characterized in that oxygenant is ammonium persulphate, Potassium Persulphate or hydrogen peroxide in said oxygenant-reductive agent-organic diazo salt composite initiation system, reductive agent is S-WAT, sodium bisulfite, ferrous sulfate, triethoxy amine or Tetramethyl Ethylene Diamine.

5. according to the preparation method of the described anionic copolymer aqueous dispersion of claim 1, it is characterized in that the limiting viscosity of dispersion agent in 1M NaCl is 0.5～7.0dL/g.