DE1181914B - Process for the production of mixed polymers from acrylic acid amide and vinyl aromatic compounds - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C08f

German class: 39 c -25/01

Number: 1181914

File number: D 31091IV d / 39 c

Registration date: 17th Wed 1959

Opening day: November 19, 1964

It is known to use certain sulfonic acid compounds containing the ethylene group Ν, Ν'-alkylenediacrylic acid amide to form insoluble ion exchange resins to mix-polymerize.

It is also known from German patent specification 672 021, mixtures of styrene and acrylic acid amide to mix-polymerize to resin-like solids, this process mainly the The aim is to modify the properties of polystyrene. When following these known procedures water-soluble polyelectrolytes are produced by polymerizing styrene and acrylic acid together inevitably result in polycarboxylic acids, which are known to be protective colloids, however, they are not suitable as flocculants.

The production of copolymers from acrylic acid amide with acrylic or methacrylic acid alkyl esters is known from German Auslegeschrift 1015 225; however, the copolymers which can be achieved in this way are nonionic and hydrophobic Character and are in contrast to the copolymers produced according to the invention effective as suspending surfactants. Finally, U.S. Patent 2,837,500 describes vinyl aromatic sulfonic acids or their salts can also be copolymerized with methacrylic acid amide. Although those mentioned in the United States patent indicated copolymers both because of the type and because of the used The proportions of the monomers do not correspond to the copolymers that can be prepared according to the invention, do they have flocculating properties to a certain extent. How, however, on the basis of carried out Comparative tests could be shown is the copolymer produced according to the USA patent specification a decidedly inferior flocculant than the product made in accordance with the invention. A process for the production of copolymers by polymerizing 99 to 90 mol percent acrylic acid amide and 1 to 10 mol percent of other monomers in the presence of Water and catalysts found at a pH between 3 and 9, which is characterized is that as further monomers vinyl aromatic compounds of the formula

XSO ₃ - (CH ₂ V - <

• CH = CH,

in which X is a hydrogen atom, alkali or alkaline earth method for the production of copolymers from acrylic acid amide and vinyl aromatic compounds

Applicant:

The Dow Chemical Company,

Midland, me. (V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:
Giffin Denison Jones,
Midland, me. (V. St. A.)

metal, R is a hydrogen atom or a hydrocarbon radical having 1 to 3 carbon atoms and η is 0 or 1, can be used.

The polymers prepared according to the invention are water-soluble copolymers, the flocculating ones When added to aqueous solutions, they have finely divided, solid mineral properties or contain inorganic substances in suspension.

The vinyl aromatic sulfonic acids that are used to produce the copolymer can include vinylbenzylsulfonic acid and monovinylbenzenesulfonic acid. The sulfonates that used are copolymerizable alkali and alkaline earth salts of monovinylbenzenesulfonic acid, z. B. the sodium, potassium, ammonium, calcium and magnesium salts, and alkylated derivatives of Monovinylbenzenesulfonic acid.

No more than two lower alkyl radicals are bonded directly to the nucleus, each of which is 1 to Contains 3 carbon atoms.

Although the vinyl aromatic sulfonic acids themselves are used as monomers for carrying out the invention Process can be used, the alkali and alkaline earth salts of the acids by far preferred because the acids are less stable than the salts and when stored for Tend homopolymerization. Now if a copolymer is desired, add the hydrogen ions Instead of containing alkali or alkaline earth ions, the latter can be replaced by hydrogen by adding a Solution of the polymer is sent through appropriately pretreated cation exchange resins.

Preferred examples of sulfonated vinyl aromatic compounds that are used to produce the mixed

409 728/503

3 4

Polymer can be used are at least 2.5 cP. It was made by S c h ο 11 a n Sodium salts of vinylbenzylsulfonic acid, vinylben- in macromolecules. Chemie, 15, p. 169 (1954), shown zolsulfonsäure, Vinyltoluenesulfonsäure, Vinyläthylben- that numerical values for the intrinsic viscosity of zolsulfonic acid, vinylisopropylbenzenesulfonic acid and acrylic acid amide polymers between 2 and 5 ziem-vinylxylene sulfonic acid. 5 borrowed close to the values for the viscosity in centi-

Water is the preferred solvent for the poise. Implementation under the conditions specified above of the polymerizations according to the invention is z. B. a viscosity of 2.5 cP very tion process, although the polymerization is also close to an intrinsic viscosity of 2.5, which is a in aqueous solutions with a water-miscible molecular weight of 500,000, lower aliphatic alcohols. Although polyacrylic acid amide can be used as a flocculation, z. B. in aqueous solutions of methyl alcohol, means of extraordinarily high effectiveness erwie-ethyl alcohol or isopropyl alcohol that has 50 or sen, there are uses for which a contain more weight percent water. Flocculants of delayed or less intensive

The polymerization is carried out at a temperature siver effect is desired. This is the case between 0 and 100 ⁰ C, but preferably between 40 15 when a concentration of 0.15 to 5 g training and 8O ⁰ C and at atmospheric or superatmospheric pressure flocculant per liter of water in the treatment carried out. It can be used in aqueous solutions with solution required. These requirements consist of pH 3 to 9, but usually occurs when further dilution of the clarified liquid is carried out in an aqueous medium with a pH from which the suspended substance is removed between 4 and 6.5. When using the monomers 20 is undesirable. Such dilutions in aqueous solution of pH 9 or above are always undesirable when the clarified acrylic acid amide is further processed for hydrolysis to form liquid, e.g. B. in mining, acrylic acid. In aqueous solutions with a substantial increase in the amount of pH from 2.5 and below, an imidization of solutions of metallic compounds, including acrylic acid amide, takes place. 25 need to be dealt with, to finally get the metals

The imidization leads to the formation of one that is detached, costly and time consuming. net, relatively insoluble product. Copolymers of acrylic acid amide, the 1 to

The polymerization reaction is catalyzed by conventional polymerization catalysts which form 10 mol percent of a monovinylaromatic sulfone-free radicals, acids of the formula given or which are alkali or which are soluble in the reaction medium. 30 Water-soluble alkaline earth metal salts or the alkyl derivatives Since water is the usual reaction medium, such sulfonic acids are contained, and valuable water-soluble catalysts are preferred. Suitable advantages as flocculants, even in comparison with catalysts, are: sodium persulphate, potassium persul- _to the homopolymer of acrylic acid amide. fat, ammonium persulfate, hydrogen peroxide, tert.- The execution of the method according to the invention

Butyl hydroperoxide. 35 is illustrated by the following examples.

The polymer is isolated in the usual way. The monomeric sodium vinyl benzyl sulfonate (das

If an aqueous solution is used, this is also known as sodium vinyl toluene-sulfonate Product usually in the form of a viscous, gel-like), the manufacture of which is not subject get like solution. The polymer can of the invention was obtained by a by evaporating the solvent, preferably a 40 solution of 63 g of sodium sulfite in 200 g of water under reduced pressure, or by pouring within 15 hours with 70 g of 91.5% strength vinylder Solution in a water-miscible benzyl chloride solution in portions with stirring at room temperature, z. B. a lower aliphatic alcohol, temperature was treated. The vinylin used which the polymer is insoluble, due to ausbenzyl chloride, consisted mainly of p-vinyl cases are obtained, whereupon the polymer 45 benzyl chloride; but it also contained a smaller one separated, washed and dried. Amount of o- and m-isomers. Unimplemented

High molecular weight has been a hallmark of good vinylbenzyl chloride along with certain Flocculants. The vinylbenzyl chloride derivatives prepared according to the invention are extracted with benzene. The copolymer has an average mole- When the solution is quenched to 10 to 0 ° C A molecular weight of at least 500,000 and usually 50 crystallized the product, sodium vinylbenzyl sulfo far over 1,000,000. Its molecular weight varies naturally, along with some of the resulting with the relative proportions of sodium chloride used and with some unreacted Na monomer and with the changes of the Polymeri- triumsulfit from. The crystals contained only one sation conditions. The molecular weight can be derived from part of the sodium chloride formed because of this the viscosity can be calculated; the higher the Vis- 55 is more soluble than the sulfonate. By determination viscosity, the higher the molecular weight. The iodine number of the water-soluble crystals that make up the Viscosity of the copolymer is contained by unsaturated vinyl group, the content was make a 0.5% solution of the same in a sodium vinylbenzyl sulfonate found to be 76.9%. 2% aqueous sodium chloride solution with pH 3 The presence of some sodium chloride in the to 3.5 according to the method of P. M. Fuoss, 60 crystals did not affect the subsequent described in J. Polym. Science, 3, pp. 602/603 (1948), Polymerization in Aqueous Solution. The existing and also in Annais New York Acad. of Science, sodium sulfite acted as an activator for the acrylic acid-51, Pp. 836 to 851 (1949). The ionic action of amide peroxide, which is generally present. That the sulfonate group is suppressed so that one had acrylic acid amide used in this example Relationship between molecular weight and viscosity 65 can contain 5 to 7 parts of acrylic acid amide can be that with the nonionic peroxide per 1,000,000 parts of acrylic acid amide; Acrylic groups is comparable. The viscosity of such an acid amide peroxide is a water-soluble, free radi-solution, determined with an Ostwald viscometer, calcium-forming catalyst.

5 6

Example 1 the persulfate catalyst - tends to sink. The copolymerization of acrylic acid amide and the mixed polymer formed was precipitated from lower alkyl alcohols with a mixture of sodium vinylbenzyl sulfonate and then carried out as follows: A solution of 9.5 g of acrylic acid amide and dried. The analysis of the polymer showed 0.65 g of sodium vinylbenzylsulfonate of 76.9% strength ⁵ 2.72% sulfur, which was a content of sodium purity, which had been obtained above, in 40 g of vinylbenzenesulfonate of 17.42 percent by weight dewatered in a Glass ampoule given. Who speaks. The molar content of sodium vinylbenzene pH was brought to 5 with hydrochloric acid and sulfonate in the copolymer was 6.8% and the ampoule was sealed. There was no catalyst of the acrylic acid amide, correspondingly 93.2%. added, since the presence of sodium sulfite. A 0.5% solution of the copolymer in and acrylic acid amide peroxide to initiate the reaction water was sufficient as in Examples 1 and 2 in one ion. The polymerization was added ° / ₀ sodium chloride solution of pH 3 15 Hours 2 and long carried out at room temperature. The resulting viscosity determined to be 3.97 cP,
Dete copolymer was made with methanol. .
precipitated and filtered off. By sulfur determination i5 Example 4
the sodium content of 200 ecm in an aqueous solution of 10% acrylic vinylbenzyl sulfonate in the copolymer was determined to be 3.25 percent by weight, ie acid amide, 0.5% disodium monohydrogen phosphate, 1.07 mol percent. The resulting mixed 0.5% sodium dihydrogen phosphate and 0.01% capolymer thus consisted of 1.07 mol percent of sulfolium persulfate of pH 6.5 with 15 ecm of a natural and 98.93 mol percent of acrylic acid amide. ao 10% strength aqueous solution of sodium vinylbenzene-The viscosity of the copolymer was mixed to form sulfonate, which also determined a pH of 3.12 cP, in that sufficient polymer was 6.5. Pre-purified nitrogen was dissolved in a 0.5% strength solution in a 2% strength sodium chloride solution for 10 minutes through the resulting monomer mixture. directed. The mixture was then 15 hours at Higher yields are, however, usually polymerized by 25 8O ⁰ C. The resulting mixed polymer addition of a water-soluble catalyst, such as kasat, was precipitated with methanol and dried with lithium or sodium persulfate. Nitrogen or and weighed 27.5 g. The content of sodium vinylbenzene, another inert gas, used to remove the sulfonate was 15.1 percent by weight, that is, the gaseous oxygen from the monomer mixture mixed polymer contained 5.8 mol percent of surfonate, since oxygen was found to be the poly-3 ° and 94.2 Mole percent acrylic acid amide. The viscosity inhibits merization until it is consumed by reaction with a 0.5% strength aqueous solution of the mixed polymer mixture, possibly with formation of a sats in a 2% strength aqueous sodium chloride solution of peroxide. was 2.23 cP, as in the previous examples

". . , “Definitely play.

Example 2 ₃₅ ^r

A solution of 0.5 g of sodium vinylbenzenesulfo-

Nat, 9.5 g of acrylic acid amide and 0.045 g of potassium per 237.5 ecm of a solution of 10 percent by weight sulfate in 90 ecm of water were brought to pH 5 with concentrated acrylic acid amide, 0.5% disodium monohydrogenphos-hydrochloric acid. The solution was freed from phate, 0.5% sodium dihydrogen phosphate and 0.01% undesired dissolved gases such as oxygen, 4 ° potassium persulphate of pH 6.5 was increased to 12.5 ecm by adding 10% nitrogen pre-cleaned for 15 minutes. igen aqueous solution of sodium vinyl was bubbled through. It was then given benzylsulphonate of pH 6.5 for 20Va hours. The resulting at 6O ⁰ C copolymerized. The resulting mixed mixed solution was flushed with nitrogen for 10 minutes. Polymer was precipitated with methanol and then polymerized at 60 ° C. After 15 hours, dried, after which 10 g of product were obtained. In 45 the polymerization was complete. Analysis showed the product contained 0.82 percent by weight sulfur. that the copolymer contained 4.05 percent by weight, which corresponds to 5.27 percent by weight of sodium vinyl chemically bound sulfonate; the molar benzenesulfonate in the copolymer. The molar content of sulfonate was thus 1.5 mol percent and the content of surfonate was about 1.9 mol percent and of acrylic acid amide 98.5 mol percent. The viscosity of the acrylate is about 98.1 mole percent. The viscosity 5 ° of a 0.5% strength aqueous solution of the mixed polymer of a 0.5% strength aqueous solution of the polymer merisate in a 2% strength aqueous sodium chloride in a 2% strength aqueous sodium chloride solution was 6.91 cP.

pH 3 was 4.77 cP. To prove advantageous properties were

. a copolymer of 5% sodium vinylbenzene

Example 3 _{55 sulfonate and} 950 ^ acrylic acid amide (according to the

225 ecm of an aqueous solution of 10% by weight of Example 2) and a homopolymer of percent acrylic acid amide, 0.5% disodium monohydroacrylic acid amide (prepared by the process of gene phosphate, 0.5% sodium dihydrogen phosphate and British patent 631592), which because of its 0 , 01% of potassium persulfate (a free radical forming superior flocculating properties compared to anwasserlöslicher polymerization catalyst) of pH 6.5 60 whose previously known flocculating agents have been known to 25 cc of a 10% ^en aqueous solution is, with respect to examined their flocculating effect, given by sodium vinylbenzenesulfonate, the also- A slurry of acid leached if had a pH of 6.5. Pre-purified South African uranium ore, which consisted of 60% suspen-nitrogen, was blown through the solution of mineral particles and 40% water for 15 minutes; the solution was then 15 hours at 65 and which had pH 1.9 was filtered. There were copolymerized 6O ⁰ C. The sodium hydrogen phosphate aqueous solutions of different concentrations of phate regulate the pH value as a buffer, the - true- polyacrylic acid amide and, according to Example 2, the copolymer apparently obtained by the formation of sulfuric acid by the present invention

sats made. The total amount of flocculant was - regardless of the concentration of the added solution - 0.05 kg flocculant in all cases per ton of suspended substance.

In a commercially available continuous filter device, the rotatable filter becomes only one Submerged a fraction of the time required for each revolution in the slurry to be filtered. A rotation time of 45 seconds with sufficient depth of slurry to pass each Immersing the given area of the filter for about a third of the rotation time is common Operating conditions. These conditions were therefore chosen as an example for technical operation. The filter cake was peeled off the filter and weighed. The rate of filtration was determined.

The daily filtration rate in kilograms per square meter was calculated by multiplying the Weight of the filter cake per square meter that accumulates during one revolution, with the number of revolutions found in 24 hours. The most effective polymer had a viscosity of 4 cP or more, which corresponds to a molecular weight of 1,000,000 or more. The results are shown in Table I.

Table I.

The drawing graphically shows the superiority of the copolymer of Example 2, that of 5 mole percent Sodium vinylbenzenesulfonate and 95 mole percent acrylic acid amide exist as flocculants compared to polyacrylamide, which is itself a very good flocculant at these concentrations.

The horizontal coordinate of the drawing is the concentration of the flocculant solution in grams per liter (total weight of flocculant to weight of suspended substance remains constant); the vertical coordinate shows the filter resistance based on the constant k \ which is determined by measuring the resistance of the filter cake. The constant k ' is calculated as follows:

k,

where ρ is the density of the filtrate in grams per cubic centimeter, J _{1 is} the weight in grams of the solid matter in the treated slurry, s _{2 is} the weight in grams of the solid matter in a filter cake saturated with filtrate, and k is a constant given by the following equation :

Con Trains Filter ² / day)
after center sat speed 5 minutes middle tion lot (kg / m
after 13 700 (g / l) (kg / t) 1 minute 15 350 Polyacrylic acid amide 0.4 0.038 14 600 Polyacrylic acid amide 0.4 0.05 17 480 16 630 Mixed polymer (Example 2) 0.4 0.038 20 600 19 500 Mixed polymer - (Example 2) 0.4 0.05 24 450 Blank sample - - ■ 5 070

k =

where t is the time required for a 30 volume ν of filtrate to pass through a cake consisting of 1 g of dry solids deposited on the filter, where time c is required for the volume ν of filtrate alone to pass through the filter is. The units are selected in the cgs 35 system. The amount is therefore obtained by taking the time required to pass a certain volume of filtrate in cubic centimeters through a cake made from g grams of dry solids which have been treated by filtration from the solutions of polyacrylamide which have been treated in the desired manner in the 4 ° slurry is measured in seconds; k ' is a measure of the filterability of the slurry when deposited on the same filter used in determining k.

A second filtration was carried out according to the method described above, with the additives (the copolymer from Example 1 and polyacrylic acid amide) in a concentration of 0.4 g / l and

45

Canadian Patent 522,850 within a wide range of concentrations including the Area of Table I listed as an excellent flocculant. The results of Table I show however, that at concentrations of 0.4 g / l, which corresponds to approximately 0.04 g per 100 g or 0.04%, the The copolymer was clearly superior to the homopolymer. At lower concentrations (the not shown here) the polyacrylamide was superior. However, there are cases where concentrations of flocculant solutions of 0.04% or more are desirable because the treated dispersions would be too diluted if much lower concentrations are used.

m a total amount as indicated in Table II were used.

Another sample of acid leached South African uranium ore became a 50% grade Prepared slurry of pH 1.6. The results are given in Table II.

Table II
Determination of the effectiveness of flocculants in the filtration of African ore

Filtration speed (kg / m ^! / Day)

middle

° / o solid matter after kg / t in the cake 5 minutes after 73.8 1 minute 77.2 74.6 79.5 0.025 78.6 81.7 0.038 80.0 82.9 0.025 80.4 0.038 79.7

after 1 minute

after 5 minutes

Blank sample

Polyacrylic acid amide, 9.4 cP

Mixed polymer

95% acrylic acid amide

5% sodium p-vinylbenzyl sulfonate 2 945 10 570 17 800

20 900 28 350

2,450

9 330

15 600

18 300 23 500

ίο

Another sample of South African ore was divided into three parts. Two parts were treated with polyacrylamide of different viscosities and the other sample was treated with the copolymer according to Example 2. The polymers were added as 0.04 ° / ₀ by weight solutions in an amount such that 0.1 kg of polymer per tonne of solids present in all approaches. The slurry contained 49.5% suspended solids at pH 1.5. Table III gives the results obtained.

Table III
Determination of the effectiveness of flocculants in uranium ore *

Polymer used

Time before filtering 15 minutes minute I 5 minutes 2560 4130 2110 3030 3610 6540 854 917 3010 2090 3860 917

Polyacrylic acid amide, 8.7 cP

Polyacrylic acid amide, 29.4 cP

Copolymer of 95% acrylic acid amide and 5% sodium p-vinylbenzenesulfonate; 4.77 cP

Blank sample

* Values expressed in kilograms per square meter per day; pH 1.5; 49.5% solids; Density 1.46 g / ccm; Cycle time 45 seconds; 0.1 kg flocculant per ton of solids than 0.04 ° ₀ solution added /.

Claims (1)

Claim: Process for the production of copolymers by polymerizing 99 to 90 mol percent Acrylic acid amide and 1 to 10 mol percent of other monomers in the presence of water and catalysts at a pH between 3 and 9, characterized in that that as further monomers vinyl aromatic compounds of the formula - (CH ₂ ) " CH = CH ₂ in which X is a hydrogen atom, an alkali metal or alkaline earth metal, R is a hydrogen atom or a hydrocarbon radical having 1 to 3 carbon atoms and η is 0 or 1, are used. 3ο Considered publications: German Patent No. 672 021; German AuslegescbriftrNr; 1015 225; U.S. Patent No. 2,837,500; French Patent No. 842 186;
Krezil, Kurzes Handbuch der Polymerisierungstechnik, Vol. II, Mehrstoffpolymerisierung (1941), p. 156. When the registration was announced, 5 pages of the test report were laid out. 1 sheet of drawings 409 728/503 11.64 © Bundesdruckerei Berlin