SU1154290A1 - Method of obtaining acrylamide copolymers - Google Patents

Description

The invention relates to the preparation of copolymers of acrylamide, in particular, with derivatives of acrylic acid (substituted with branched acids of my acrylic series), which can also be used as flocculants. Methods are known for the preparation of copolymers of acrylamide with acrylic and methacrylic (OS-methyl acrylic) acids in a solvent medium. As copolymerization initiators, potassium, sodium, ammonium l and 2 persulfates are used. However, these methods are characterized by insufficiently high flocculating ability of the obtained copolymers. The closest to the proposed technical essence and the achieved result is a method for producing acrylamide copolymers by radical copolymerization of acrylamide with acrylic acids (acrylic, methacrylic) in the presence of a radical polymerization catalyst (a mixture of potassium, sodium or ammonium persulfate with an aliphatic amine and Lewis acid) in solvent medium (water-acetone mixture). The amount of acrylamide is 65-99% by weight of copolymers h. However, the effective industrial use of acrylamide copolymers with the lower homologues of acrylic acids (acrylic and methacrylic acids) as flocculants is prevented by a sharp decrease in the flocculating activity of the copolymers in the presence of water-soluble salts, such as potassium, sodium, and magnesium sulphates. The drop in the flocculating activity of copolymers of this type can be explained by the fact that water-soluble salts cause globularization (coagulation) of the macromole of copolymers. Especially significant is the decrease in the activity of copolymers under conditions of elevated temperatures of electrolyte solutions, for example, when obtaining pure salts by the method of dissolution-crystallization. The decrease in flocculation activity necessitates a corresponding increase in its consumption, which adversely affects the economic indicators of production. The purpose of the invention is to increase the flocculating activity of the copolymers in salt solutions. This goal is achieved by the fact that according to the method for producing acrylamide copolymers by radical copolymerization of acrylamide with acrylic acids in the presence of a radical polymerization catalyst in a solvent medium, X, p -substituted acids of the general formula RrH (where Rj and Rg - saturation and unsaturated hydrocarbon radicals of normal or iso-construction with the number of carbon atoms in Rj 2-3 and R-3-14, prewash at pH 8-12, taken in an amount of 10-40% of the total mass of comonomers, and the solvent is water. The proposed method for the copolymerization of acrylamide with pi, -substituted acids of acrylic series was tested in laboratory conditions with the following order of operations: - branched acid (or mixture of acids) in the amount of 10-40% of the total the masses of the acid (mixture of acids) and acrylamide are previously minted with potassium or sodium hydroxide at pH values of 8-12, thus converting the acid (mixture of acids) to a water-soluble form; The required amount of an aqueous solution of acrylamide is added to the resulting aqueous solution of branched acid soap (a mixture of acids), and potassium, sodium or ammonium persulfate copolymerization initiator is added in an amount of 1% of the total weight of the starting monomers. After 24 hours exposure at 8-10 ° C, a water copolymer gel is obtained. The concentration of the copolymer in the gel is determined by the initial concentration of monomers in the aqueous solutions. The copolymers of acrylamide and o, / 3 -substituted branched acids of the acrylic series thus obtained have a significantly greater flocculating activity compared with similar copolymers obtained by known methods. This is due to the higher molecular weight and regularity of incorporation of carboxylic acid copolymer macromolecules into the chains. Branched molecules interfere with the globulization of flocculant in usable electrolyte solutions. As a result of the copolymerization reaction, the proposed method produces copolymer aqueous gels containing .% (depending on the concentration of the initial aqueous solutions of soaps of i-branched acids, acrylamide). The retention of branched acids in the copolymer is tO-AO wt. A content of 40% by weight is the maximum permissible value, since with further increase in concentration, the excess of branched acids does not enter into the reaction, remaining as an organic layer of derivatives of mineral and branched acids over the more dense gel of the copolymer. Such a phenomenon can be explained by the overlapping of copolymer macromolecules by branched units in the case of exceeding the optimal limits of the ratio of acrylamide: branched chain of lots. The molecular weight of the copolymers obtained is in the range of 2-10 3 1-0.e. This value can also be increased or decreased with changes in the degree of polymerization, which can be controlled by the amount of catalysts added and the process temperature. The copolymer of acrylamide and σ, раз-branched acid C |O, obtained by the proposed method, has a significantly greater flocculating activity than similar copolymers obtained in a known manner (Table. This confirms the assumption of a greater molecular weight and regularity of inclusions in the polymer chain of branched acid units. According to the proposed method, copolymers of acrylamide are synthesized with various representatives of branched acrylic acid: oi-branched acid Cg; fti-branched acid C | o, and the same cubic product of the production of branched C10 acid - a mixture of branched acidic C) o, C (5 and Cjg in a mass ratio of 6: 3: 1, respectively (Table 2). The content of α-branched acids in the active part of the copolymers varies within 10 -40% w / w (Table 3). The flocculating activity is checked by a standard method at deposition temperatures of 20 and 90 s. In addition, the known flocculants are tested under the same conditions: polyacrylamide - technical gel and copolymers of acrylamide with acrylic and methacrylamide with methacrylic with acids. Example 1 (the proposed method). 21 g of crystalline acrylamide is dissolved in 119 g of water (solution 1). 9 g of branched acid IOZ with an aqueous solution of sodium hydroxide are added up to pH 8-12 for a water solution of branched acid sodium soap (solution 2). Solutions 1 and 2 are mixed. Ammonium persulfate (0.3 g (1% by weight of the initial monomers) is added at a temperature. The reaction mixture is kept at a temperature for 24 hours. The result is a 15% aqueous gel of a copolymer containing 30% by weight of Co-branched acid C. , (sample 1). PRI mme R 2. (by a known method). 21 g of crystalline acrylamide and 9 g of branched acid C are dissolved (about 170 g of a sodium-acetone mixture containing 20% by weight of acetone, after which 0.3 g (1% by weight of the starting monomers) of ammonium persulfate and triethanol are added. and 0.6 g (2% by weight of the starting monomers) aluminum chloride, and held for 40 h (sample I). Evaluation of the flocculating activity is carried out as follows. Prepare 0.25% (by weight) working a solution of the copolymer in saturated with potassium chloride and sodium aqueous liquor (20.5% sodium, 1-, 5% potassium chloride). This operation the solution is carried out with a weak stirring on a magnetic stirrer. The time of dissolution of the copolymer pre-swollen during the day in the bulk liquor does not exceed 4-5 hours. The prepared working solution of the copolymer in the liquor is used to precipitate clay-carbonate sludge in potassium chloride and liquor at 20 and determine the rate of deposition of sludge. The results of the evaluation of the flocculating activity of acrylic copolymers # 1 yes with 00-branched acid Xu (

acid), obtained in examples 1 and 3 are shown in table. one.

Similarly, semi-copolymers with acids. The structure of hydrocarbon radicals included in the molecules of acrylic acids is given in Table. 2. The composition of the copolymers is listed in Table. 3, and the results of tests of flocculating activity in the table. four.

From the results presented in Table 4, it follows that the flocculating activity of the proposed flocculants is significantly higher in comparison with the known ones.

Table

The deposition rate of molecules using the sample, m / h

Continuation of table

39.4

13.5 43.3 17.3 46.6 20.8 58.5 36.9 66.8 51.6 65.5 73.5

table 2

оС-Isopropyl, / 3 -isobutyl acrylic (2-isopropyl, 5-methylhexene; oi-branched acid C)

cd-Branched Acid C

15

SNGsn

x

SN, SNZ

SNS C,

CH2

yon

eleven

g -

n, si-cn

ti-Branched Cj acid

Polyacrylamide - technical gel Acrylamide copolymer with acrylic acid Methacrylamide copolymer with methacrylic acid Copolymer of acrrlamide with “i-branched acid С Copolymer of acrylamide with os-branched acid C.

Copolymer of acrylamide with ti-branched acid C, Copolymer of acrylamide with oi-branched acid Cj, (example 1)

Acrylamide copolymer with C-branched acid C,

Copolymer of acrylamide with the bottom product of the production of 0-branched acid C (mixture of acids SSC,

1 g.

Acrylamide copolymer with bottom product of o-branched acid production (mixture of acids C | Q,

15 )

Continuation of table 2

Sn,

HH,

CH; H CH,

Sn

CH2

SN CHZ

I I with -sn

I I

SNF

II

.sn

SNZ NZ

Table 3

Continuation of Table 3 Sludge sedimentation rate, m / h Flow rate at temperature, С l nta, :: JZZZI

20

9Q

20

90

46,652,048,354,152,355.9 54.0 58,255,459,342,649.3

58,563,859,665,164,068,466,571,566,671,354,962,5

66,871,967,472,5.72,077.0 75.1 80,774.1 79,463,771.8

73,578,373,578,378,388,781,887,880,085,770,879.2

Continuation of table 4

90 20 90 20 90 20 90 solutions of floc ntov ILEH

Claims (1)

A method of producing acrylamide copolymers by the radical copolymerization of acrylamide with acrylic acids in the presence of a radical polymerisation catalyst in a solvent medium, the only difference being that, in order to increase the flocculating activity of the copolymers in saline solutions, as acids of the acrylic series, use “Г, ft-substituted acids of the general formula where Rf and R ₂ are saturated or unsaturated hydrocarbon radicals of normal or isostructure with the number of carbon atoms in R <= 2-3 and Ig = 3-14, previously saponified at pH 8-12, taken in an amount of 10-40% of the total mass of comonomers, and water as a solvent. SU ,,., 1154290>