JPS6132047B2 - - Google Patents

Description

[Detailed description of the invention]

In recent years, many substrates such as sewage sewage, cellulose fibers and fines used for retention and freeness, metal ore processing products, wood waste, coal tailings, steel mill dust and sinter dust, and drinking water. The use of copolymer emulsions of acrylamide and acrylic acid as effective coagulants is becoming increasingly important. These emulsions are usually in the form of water-in-oil, and when water is added to them, they become oil-in-water emulsions, during which the polymer rapidly dissolves in the water. This type of emulsion and dissolution operation is described in US Pat.
This is shown in each specification of the issue. Add these patents as reference materials. Although these emulsions are very effective when used as coagulants, their effectiveness tends to decrease at temperatures such as the alternating freezing and thawing conditions found in many regions during the winter. Repeated temperature cycling causes the emulsion to coagulate, causing the finely dispersed particles of the polymer to aggregate into large clumps, thereby rapidly reducing its usefulness as a coagulant. The novel emulsion of the present invention has excellent freeze-thaw properties. In other words, this emulsion is frozen.
It does not aggregate to the extent that it loses its usefulness as a coagulant when subjected to thawing conditions. The emulsion of the present invention has stability under freeze-thaw conditions as well as other attractive properties of existing emulsions, such as stability at high temperatures, good conversion when diluted with water, and high resistance to hard water. Retains resistance and good dispersibility in water after conversion. This superior combination of properties is provided by the use of a limited amount of partially neutralized acrylic acid and a limited amount of a convertible surfactant in the copolymer. . The present invention comprises a freeze-thaw stable, self-converting, water-in-oil emulsion containing a dispersion of finely divided polymer particles within the emulsion. The emulsion consists of the following A-D: (A) about 70% by weight based on the total weight of A, B and C;
% (weight percentage, hereinafter the same) to about 95% aqueous phase, this aqueous phase consisting of the following (1) and (2): (1) about 27% to about 68% based on the total weight of A
a water-soluble acrylamide-acrylic acid copolymer having a concentration of from about 25% to about 35% of the total weight of the copolymer, provided that about 50% to about 75% of the acrylic acid (the remainder being acrylamide) is neutralized. (2) water in an amount ranging from about 32% to about 73% of the total weight of A; (B) about 5%, based on the combined weight of A, B, and C;
% to about 30% of liquid hydrocarbons, (C) based on the combined weight of A, B and C, about
a water-in-oil emulsifier dispersed between the aqueous phase and the liquid hydrocarbon phase at a concentration ranging from 0.1% to about 15.0%; and (D) about 1 mole of an aliphatic having about 12 to 18 carbon atoms. A convertible surfactant comprising the reaction product of an alcohol and about 6 to 10 moles of ethylene oxide in an amount ranging from about 2.0% to about 3.2% or less, based on the total amount of A, B, C, and D. As mentioned above, the aqueous phase of the novel emulsion of the present invention consists of an acrylamide-acrylic acid copolymer and water. This copolymer contains 65 to 75 acrylamide
% and 25-35% acrylic acid. About 50% to about 75% of the acrylic acid must be neutralized to impart the freeze-thaw stability described above to the final composition. It is desirable to neutralize acrylic acid before copolymerizing the monomers. However, it can also be carried out after the copolymerization if desired. By contacting the acrylic acid monomer in an aqueous solution containing a suitable amount of any known neutralizing agent such as an alkali metal or alkaline earth metal hydroxide, ammonia, an amine or the like in a conventional manner. Neutralization takes place. The pH of the resulting aqueous phase is approximately
In the range of 4.5 to about 5.5. A preferred sequence is to dissolve acrylamide and acrylic acid in water to the desired solids concentration;
Chelating reagents such as ethylenediaminetetraacetic acid disodium salt are added to chelate metal ions such as those introduced during the acrylamide manufacturing process.
Neutralization of the acrylic acid is then carried out, followed by the addition of a small amount of iron as a component of the initiator, as detailed below. As described below, it is desirable to add the peroxide portion of the redox catalyst system (described below) at or after this time. After preparing the aqueous phase as described above, the aqueous phase is injected into the oil phase, at which point an oil solution containing an oil-in-water emulsifier is created. Any oil may be used for this purpose, and these oils are shown in the US patent specifications cited above. A suitable oil is AMSCO, commercially available from Union Oil Co., California.
It is OMS (product name). Its approximate composition is 86.9% paraffin, 13.0% naphthenes, and 0.1% aromatics.
% clear oily liquid. Molecular weight approximately 170, specific gravity
0.755 [15.5℃ (60〓)] Viscosity 1.4cps [25℃ (77
〓)〕, freezing point -31.6℃ (-25〓) or lower, boiling point 204
℃ (399〓), flash point (TCC) 52.2℃ (126〓),
and insoluble in water. Specific heat is 37.7℃ (100〓)
0.499BTU/16 at 〓 and 93.3℃ (200〓)
It is 0.588BTU/16.〓. Any available water-in-oil emulsifier may be used, although those described in the above-mentioned US patents are examples. Sorbitan monooleate is a suitable emulsifier. If the oxidizer portion of the redox catalyst system described above has not already been added, this can be done after forming the water-in-oil emulsion by stirring the oil and water phases to ensure a homogeneous blend. Add. This component is added as an aqueous solution of the monomer emulsion, and its concentration is from about 10 to about 500 parts per million parts of monomer, preferably from 25 to 150 ppm. The redox catalyst system used can be any, such as bromate-sulfite systems, peroxide-chlorine sulfite systems, hydroperoxide-bisulfite systems, and the like. Still other free radical catalyst systems may be used. For example azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, potassium persulfate and the well-known analogues. When using a single component catalyst system, it is desirable not to add the catalyst system to the monomer emulsion until the monomers have been converted to polymer. However, in the preferred form of the invention, the oxidant portion of the redox catalyst system comprising t-butyl hydroperoxide and sodium metabisulfite is first added to the monomer emulsion. It is preferred to use iron as a component of the catalyst system in an amount of about 1 to about 10 ppm by weight of monomer. The iron can be added externally to the aqueous phase as described above, or it can be present as an inherent component in the water or monomer itself. The amount of the reducing agent portion of the redox catalyst used should range from about 10 to about 500 ppm, preferably 50 to 200 ppm, based on the weight of monomer. After the reaction mixture is prepared as described above, nitrogen gas is used to completely remove oxygen from the system. The catalyst system is then placed in a monomer emulsion containing the oxidizing agent portion for about 2 hours to about 24 hours, preferably about 4 hours.
Add the reductant portion of the catalyst system using a pump over ~16 hours to complete the conversion. This process takes a long time if the catalyst concentration is low, and takes a short time if the catalyst concentration is high. The temperature of the reactants is between about 25°C and about 55°C.
The temperature should preferably be kept in the range of 35°C to 45°C. After the catalyst components are added and the copolymerization is substantially complete, sodium metabisulfite, the reducing agent portion of the catalyst, is added to the resulting copolymer at the copolymerization temperature to stabilize the copolymer product. By then adding more than about 2.0% and less than about 3.2% of the convertible surfactant mixture described above, the novel emulsion of the present invention, a so-called one-package emul, in which conversion is achieved only by the addition of water, is produced. Jiyoung is prepared. This range is important because if less than 2.0% is added, the water-in-oil emulsion will only partially convert to oil-in-water emulsion, and if more than 3.2% is added, the water-in-oil emulsion will only partially convert. This is because water-in-oil emulsions are too viscous and difficult to handle effectively, and their freeze-thaw stability is also reduced. Furthermore, when the emulsion of the present invention is converted and used for water treatment, when the calcium concentration in the water to be treated is trace to moderate, the emulsion with a low concentration of surfactant is effective; It has been found that a larger amount of convertible surfactant-containing emulsion is required when calcium is included. The following examples are set forth for the purpose of illustrating the invention only and should not be construed as limiting the invention except as described in the claims. Parts and percentages in the examples are by weight unless otherwise specified. Example 1 Into a suitable reaction vessel are added 313.0 parts of a 47.3% aqueous solution of acrylamide, 64.0 parts of acrylic acid, and 167.0 parts of deionized water. 39.6 parts of concentrated aqueous ammonia (28.6% NH ₃ ), which neutralizes 75% of the carboxyl groups of acrylic acid, is added to the resulting solution.
The pH of the resulting solution is approximately 5.3.
0.848 parts of ethylenediaminetetraacetic acid disodium salt and 0.23 parts of ferric sulfate hydrate ( _Fe2
(SO ₄ ) ₃ 72% (4.5 parts/1000 parts water) is added. The above is the composition of the monomer aqueous phase. The oil phase contains 18.0 parts of sorbitan monooleate.
Prepared by dissolving in 308.0 parts of commercially available AMSCO OMS (Union Oil Company, clear oily liquid). Add the entire oil phase system described above to a suitable high speed homogenizer, operate the homogenizer and gradually add the monomer aqueous phase to form an emulsion with a viscosity of 725 cps. The particle size in the dispersed phase of the resulting emulsion is less than about 2.5 microns. Add the entire emulsion system described above to a suitable reaction vessel with stirring. 70.0ppm qt relative to monomer amount
-Add butyl hydroperoxide. The obtained medium is washed with nitrogen gas to remove oxygen. Sodium metabisulfite was pumped into the vessel over a period of 6 hours at approximately 40°C with stirring, then at approximately 40°C.
Add 200 ppm (based on monomer weight). The conversion rate of acrylamide in the obtained viscous emulsion is
98.97%, the conversion rate of acrylic acid is 99.10%.
Polymer solids is 25.48%, standard viscosity is 6.6cps, PH is
It is 4.8. Stabilization of the polymer emulsion is achieved by adding 27.6 parts of 30% sodium metabisulfite solution. The emulsion is kept under polymerization conditions (40° C. for 60 minutes) to almost completely react the remaining acrylamide and acrylic acid. The emulsion contains 0.4% sodium bisulfite, which stabilizes the polymer system. A sufficient amount of the following reaction product as a converting agent is added to the resulting copolymer emulsion at 40 DEG C. over 30 minutes to give a final content of 2.3%. The reaction product used is the reaction product obtained by reacting 1 mol of a mixture of C ₁₂ -C ₁₄ chain alcohols with 7 mol of ethylene oxide. The resulting emulsion is kept at 40° C. for an additional hour to obtain a smooth, grain-free product with a viscosity of 650 cps. The particle size of the dispersed polymer phase is 2.5 microns and smaller. Standard viscosity is 6.4 cps and final solids content is 24.80%. Place 25.0 parts of the final emulsion in a suitable container and keep at a temperature of -10°C for 22 hours. Warm the chilled container to room temperature over 2 hours and gradually pour the emulsion into the second container. During this time, count the number of macroscopically recognizable coagulated grains. After the measurement is completed, the entire emulsion is transferred to the first container and kept at -10°C for 22 hours. Continue this cycle for 13 days. The same freeze-thaw test as above is carried out on an emulsion (hereinafter referred to as the second emulsion) prepared according to the same method as above, but in which the neutralization rate of acrylic acid in the emulsion is less than about 10%. The results are shown in Tables 1 and 2 below.
Weekly cycles are freeze-thaw intervals of one week.

【table】

[Table] A part of the emulsion of Example 1 was subjected to high temperature treatment together with a second emulsion having a neutralization rate of 10%, and the stability was measured by measuring the degree of molecular weight reduction using standard viscosity. At 50°C and 60°C, the emulsion of Example 1 is stable for 6 weeks and 2-3 weeks, respectively, while the sample with 10% neutralization is stable for 3-4 weeks and 1-2 weeks, respectively. A portion of the emulsion of Example 1 was poured into water that was being rapidly stirred, and the conversion performance was examined. This sample is approximately
Almost complete conversion occurred within 30 minutes (hereinafter referred to as tertiary emulsion). The conversion performance of a portion of the emulsion of Example 1 was tested on rapidly stirred water containing calcium chloride (750 ppm as CaCO ₃ ) (hereinafter referred to as the fourth emulsion). It has a conversion performance of about 93% based on the conversion of the third part. After the third and fourth conversions above, the samples were brought to room temperature for 24 hours.
Little or no separation occurs even after standing for a period of time. That is, it shows that the dispersion of oil in the aqueous phase is extremely good. Examples 2 and 3 According to the method of Example 1, but (3) 53.5 parts of acrylic acid and 158 parts of acrylamide monomer and
(4) 74.5 parts of acrylic acid and 137 parts of acrylamide monomer were used. In this case as well, freeze-thaw stability, temperature stability, conversion rate, and calcium tolerance were all excellent. No separation of the converted emulsion was observed after standing at room temperature for 24 hours. Example 4 Example 1 is again followed, but the content of the ethylene oxide-chain alcohol reaction product is increased to 3.2%. Essentially complete conversion is also obtained using water containing 750 ppm calcium carbonate (added as calcium chloride) as the solvent. Example 5 The ethylene oxide-chain alcohol reaction product of Example 1 is replaced by the equivalent of a reaction product of 1 mole of C ₁₈ chain alcohol and 10 moles of ethylene oxide. Almost similar results are obtained. Comparative Example According to Example 1 but increasing the neutralization rate of acrylic acid in the procedure to 87%. The viscosity of the copolymer solution produced by converting the obtained emulsion is
Even a 0.2% solution has such a viscosity that it is extremely difficult to handle. Example 6 The procedure of Example 1 is again followed, but the neutralization rate of acrylic acid is reduced to about 50%. The results obtained were almost the same. Example 7 The procedure of Example 1 was repeated, except that the neutralization rate of acrylic acid was 60%. The freeze-thaw test results in this case are shown in Table 3 below.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A self-rolling water-in-oil emulsion that is stable against freezing and thawing and contains a dispersion of finely granular copolymer particles therein, consisting of the following A, B, C, and D: ( A) 75% based on the total weight of A, B and C
An aqueous phase consisting of () and () in amounts ranging from 95% to 95%: () A water-soluble acrylamide-acrylic acid copolymer comprising 27% to 68% of the total weight of A. However, based on the total weight of the copolymer, 25
% to 35% is acrylic acid, the remainder is acrylamide, and further 50% to 75% of the acrylic acid is
% shall be neutralized; () water in an amount ranging from 32% to 73%, based on the total weight of A; (B) 5%, based on the total weight of A, B and C;
liquid hydrocarbon oil in an amount ranging from 25% to 25%; (C) 0.1 based on the total weight of A, B and C;
% to 15.0% of a water-in-oil emulsifier disposed between said aqueous phase and said liquid hydrocarbon; (D) based on the total weight of A, B, C and D;
A convertible surfactant comprising a reaction product of 1 mole of aliphatic alcohol having 12 to 18 carbon atoms and 6 to 10 moles of ethylene oxide in an amount ranging from more than 2.0% to less than 3.2%. 2. An emulsion according to claim 1, wherein the copolymer consists of 70% acrylamide and 30% acrylic acid. 3. The emulsion according to claim 1, in which 60% of the acrylic acid is neutralized. 4. An emulsion according to claim 1, wherein the convertible surfactant is formed by reacting 7 moles of ethylene oxide with 1 mole of a mixture of _C12 to _C14 chain alcohols. 5. The emulsion according to claim 1, wherein the aqueous phase comprises 67% water and 33% copolymer. 6. The emulsion according to claim 1, wherein the amount of convertible surfactant is 2.3%. 7. A method for preparing a self-converting emulsion stable upon freezing and thawing, characterized by comprising the following steps A, B, C, and C: (A) Mixing the following components A, B, C, and D. to form a water-in-oil emulsion, (a) 75% based on the total weight of a, b, and c.
A mixed solution of (a) and (b) in an amount of from 95% to 95%; (a) a mixture of acrylamide and acrylic acid representing 27% to 68% based on the total weight of (a), provided that the acrylic acid is neutralized by 50 to 75%; (b) water in the range of 32% to 73% based on the total weight of (a); (b) water in the range of 32% to 73% based on the total weight of 5% based on the total weight of
Liquid hydrocarbon oil in the range of 25% (C) 0.1 based on the total weight of A, B and C
(d) prior to free radical initiation consisting of sodium metabisulfite and a hydroperoxide; (B) polymerizing the above monomers under free radical polymerization conditions to form the acrylamide and (C) forming a water-in-oil emulsion containing fine particles of a neutralized copolymer of acrylic acid dispersed therein; (C) adding a convertible surfactant to the above-mentioned water-in-oil emulsion; a step of adding, provided that the activator is combined with 1 mole of an aliphatic alcohol having 12 to 18 carbon atoms in an amount exceeding 2.0% and not more than 3.2% based on the total weight of A, B, C and the activator; Reaction product of 6 to 10 moles of ethylene oxide. 8 Monomer mixture is 70% acrylamide and 30%
% of acrylic acid. 9. The method according to claim 7, wherein 60% of the acrylic acid is neutralized.