FI85586B - FOERFARANDE FOER FRAMSTAELLNING AV VATTENLOESLIGA AKRYLAMID-HOMO- OCH KOPOLYMERER GENOM EMULSIONSPOLYMERISATION. - Google Patents

Description

1 85586

Process for the preparation of water-soluble acrylamide homopolymers and copolymers by emulsion polymerization. -

The present invention relates to an improved process for the preparation of water-soluble acrylamide homo- and copolymers by emulsion polymerization starting from the corresponding monomers, the products obtained having a high concentration and advantageous properties in terms of stability and dilutability at useful concentrations.

It is well known that polyacrylamide-based polymeric compounds are either homopolymers of acrylamide having nonionic properties or copolymers of acrylamide and unsaturated vinyl derivatives having anionic or cationic properties. These compounds can also be given anionic or cationic properties. In all cases, the molecular weight of the polymers is very high and can vary from a few ’**. from one hundred thousand to the order of 10 million.

V. The aim of modern technology is to provide methods for the production of these polymers which make it possible to "obtain products with the desired molecular weight and the narrowest possible dispersion range.

These aspects are closely related to the uses of the above polymers. The range of uses for these polymers includes their use as flocculants in process fluids, industrial and municipal wastewater, and the mining industry; further oil recovery, fiber retention in the paper and board industry, fiber recovery from paper, board and fiber cement, dewatering of industrial and municipal wastewater sludge, etc.

2 85586

Acrylamide, the major monomer of such polymers, is obtained by catalytic hydrolysis of acrylonitrile with water in the presence of a metallic copper catalyst at a pH between 4 and 10, while the hydrolysis process of acrylonitrile is practically based on hydrolysis in a strongly acidic medium. One of the reasons that has accelerated this change in the manufacturing process is the finding that the catalytic process does not cause residual amounts of N-acryloyl-acrylamide. This is an impurity which, in the presence of an acrylamide monomer, can reduce the solubility of the resulting polymer in water. In this regard, it is interesting to report what is reported in U.S. Pat. No. 3,130,229 and Spanish Patent 504,916 on the effect of the acrylamide preparation process on the N-acryloyl-acrylamide content.

Starting from the monomer, there are mainly two polymerization pathways available, namely suspension polymerization and emulsion polymerization. Initially, the most widespread method was preparation in suspensions. By blending, drying and comminuting, nonionic and ionic as well as cationic, powdered polymers were prepared. The mode of action of the polymers in their applications necessitates their use as aqueous solutions, which are generally very low in concentration. As a result, the grain size of powdered polymers must be very small (up to 5 microns). In practice, these requirements have the following two disadvantages: - lumps form in the aqueous solution due to the low wettability of the polymer, and - the polymer dissolves slowly in water, necessitating the use of special filling systems (e.g.

Venturi nozzles).

li 3 85586 In addition to these two difficulties associated with the usefulness of the polymer, the method of preparation in suspension has one further disadvantage. Namely, they have various difficulties in producing the very high molecular weight polymers required by modern technologies.

As a result, water-in-oil emulsion polymerization techniques or methods have been developed. In this process, the polymerization of the monomer or monomers is carried out in a stable emulsion of water in paraffin oil or solvents such as xylene, toluene, naphtha or the like. Any known technique can be used to prepare the emulsion, such as mixing, homogenization, ultrasound, etc. However, since the stability of the emulsion is one of the essential conditions for ensuring the quality and uniformity of the polymer obtained, known surfactants with a suitable hydro-lipophilic balance are generally used: HLB).

In the preparation of acrylamide-based anionic polymers, the copolymerizable monomers may be: acrylic acid and its salts, methacrylamide, methacrylic acid and its salts, methyl, ethyl and propyl acrylate, methyl and propyl methacrylate, hydroxy methacrylate, acrylonitrile, styrene, 2-acrylamide-2-methyl-propanesulfonic acid and its salts, vinylpyrrolidine and methyl ether-vinyl.

4. * Non-ionic polymers are acrylamide homopolymers.

* ·

In the preparation of acrylamide-based cationic polymers, the copolymerizable polymers may be as follows: 4,85586

Dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary derivatives of these compounds due to their reaction with methylene chloride, methylsulphamethylpropylamide-acrylamide-acrylamide

The use of emulsion polymerization makes it possible to obtain polymers dissolved in the emulsion which have a high concentration (about 40 S) and which can be very easily diluted to the treatment concentration, if necessary.

The liquid forms of the products obtained then provide very conventional, convenient and economical storage transport options.

In the preparation of polymers, it is generally known to those skilled in the art that the emulsion polymerization process has mainly two disadvantages which adversely affect the quality and economy of the products obtained.

These disadvantages are: • · »- it is possible that during the polymerization process the emulsion‘ decomposes and precipitates water-insoluble polymer masses, * · 4 * • · - due to the exotherm of the polymerization process, it is very difficult to control the process thermally; thus, it is also difficult to control the reaction, which adversely affects the quality of the products obtained.

“Both of these problems, which are the main but not the only disadvantages, are, of course, becoming increasingly difficult to solve as the concentration of polymers in the emulsion increases.

The above-mentioned disadvantages are avoided in the manufacturing process which is the subject of the invention. The process according to the invention is based essentially on the process steps shown in the following, which, both individually and in a particularly suitable manner, make it possible to achieve the desired results.

The production process according to the invention is characterized in detail by the following features: 1. The emulsion polymerization process is started using a relatively low content of polymerizable solids, which can vary between 2 and 20% · 2. Emulsion polymerization processes use copolymerizable, interactively active ingredients with % of emulsion solids monomers.

These active surfactants are: 2.1. Vinyl derivatives of different degrees of oxyethylation, ϊ having the general formula: • * · '* * i

R O

I * CH, »C - C - O (CH-.CH-O) H. . 2 l i 9 wherein R may be a hydrogen atom or a C 1 -C 4 straight chain alkyl group and n may range from 2 to 50.

2.2 Sulfonated vinyl derivatives having the general formula: • j »•» • «• h r. No »)

: .. I * I

CH 2 · C - (CH 2) n --O - (CH 2) m.CH.CH 2 SO 3 Na where R 1 may be a hydrogen atom or a C 6 -C 6 straight chain alkyl group 6 85586, and the symbols n and m may have values from 1 to 3.

3. The concentration of polymeric material is adjusted to a concentration> 30-40% either during the polymerization process or after its completion by azeotropic distillation of the excess solvent without separating the water-soluble polymer mass in either case.

One skilled in the art can deduce from these three points the advantages and novelty of the method according to the invention. Those skilled in the art can easily conclude that the lower concentration of polymerizable material in the initial oil-in-water emulsion means less controllable heat load, and that as a result the control can be performed by technical means that are cheaper and less costly than would be required in a high power system. . However, the proposed method is not limited to these aspects, but ·. : complements the control of the polymer concentration with technically and commercially interesting values in the order of 30-40 £ by means of low-pressure azeotropic ** distillation processes. All this would not be possible ♦ · ♦ * without the use of the active surfactants described in 2.1 and 2.2; this is made possible by the fact that they take part in the polymerization process and copolymerize, giving the polymer emulsion excellent internal stability, which is much higher than that achieved by conventional methods - even with the addition of surfactants which do not polymerize. The effect of these substances, the use but not the synthesis of which is the subject of the present invention, in a conventional polymerization system • ·: makes it possible to carry out an azeotropic distillation process according to the invention during the polymerization process, or ·. without affecting the stability of the emulsion.

m m • • · 7 85586

The use of the described production method makes it possible to obtain emulsions with a very homogeneous grain size and a better degree of wetting, which facilitates the dilution of the product before use.

In the following description, the differences between the final products to be polymerized have been clarified.

Example 1 To a 700 ml reaction glass (equipped with a reflux condenser, distillate outlet, temperature control, condenser, stirrer, heating element and nitrogen purge) was added 75 g of an aliphatic linear hydrocarbon having a distillation range of 250 to 250 ° C. g of a light linear hydrocarbon having a boiling point of about 98 ° C and 5 g of sorbitan monooleate.

To this mixture was added an aqueous solution containing 95 g. . deionized water, 50 g of acrylamide and 13 g of sodium * a m. [* acrylate. The dissolved oxygen was then removed

* "by displacing it with nitrogen and the mixture was heated to about 40 ° C

• a * * ... · temperature. Then 0.2 g of sodium · · ·; persulfate. The mixture was kept at 40 ° C for 40 hours. Thereafter, the light hydrocarbon was azeotroped at low V: pressure (about 4 mm HgS).

160 g of a fully gelled product were obtained, which on quantification consisted of 51 g of a gummy, water-insoluble substance.

* '·' Example 2 ··· '**. An emulsion similar to Example 1 was prepared.

However, 5 g of a copolymerizable active ingredient of the formula · 85586 was added to the aqueous phase.

CH, O

I 3 I

CH2 - C - C - O (CH2 - CH2O) 3-H

155 g of product in the emulsion were obtained, which by analysis contained; 3 g of gelled substance. The residue was a stable emulsion consisting of 50 g of acrylamide-acrylate polymer with an RSV (reduced intrinsic viscosity) of 2Θ.

Example 3

An emulsion similar to Example 1 was prepared. However, 5 g of a copolymerizable surfactant having the formula CH,, CH2 - C - <CH2) 3 O - (CH2) 2 - CH - CH2 SO3 Na were added to the aqueous phase.

. : I

OH

m m ·· * 153 g of product in an emulsion were obtained which, by analysis · * (by filtration), contained 2 g of gelled

agent. The residue was a stable emulsion consisting of: 49 g of acrylamide-acrylate polymer with an RSV

was 32.

Example 4 To a 700 ml reaction beaker (equipped with a reflux condenser, distillate removal, temperature control, stirrer, heating element and cooling, and a nitrogen purge) was added 75 g of an aliphatic linear. a hydrocarbon having a distillation range of 200 to 250 ° C, 249 g of a light linear hydrocarbon having a boiling point of <98586 at about 98 ° C, and 5 g of sorbitan monooleate. To this mixture was added an aqueous solution containing 92 g of deionized water, 37.5 g of acrylamide and 12.5 g of dimethylaminoethyl methacrylate acetate. Dissolved oxygen was then removed by displacement with nitrogen and the mixture was heated to about 40 ° C. Then, 0.2 g of sodium persate was mixed into the mixture. The mixture was kept at 40 ° C for 4 hours. The light hydrocarbon was then azeotroped under low pressure (about 4 mm HgS). 157 g of a fully gelled product were obtained, which on quantification consisted of 48 g of a gummy, water-insoluble substance.

Example 5

An emulsion similar to Example 1 was prepared, however, 5 g of a copolymerizable interfacial active ingredient of the formula CH 2 0 1 11 was added to the aqueous phase.

CH2 = C - C - O - (CH2-CH2-O) 3 - H

. . 150 g of product in the emulsion were obtained, which, by analysis, contained 2 g of gelled material. The residue was a stable emulsion consisting of 47 g of dimethylaminoethyl-... · methacrylic acid-acrylic -po 1 yimer with an RSV: V (reduced intrinsic viscosity) of 13.

• · · 1 ·

Claims (3)

10 85586 A process for preparing emu by polymerizing high molecular weight water-soluble acrylamide polymers with a dry matter content of 30 to 40%, characterized in that it comprises the following process steps: a) the emu 1 silopolymerization process is started with a content of polymerizable solids; : b) during the emu 1 polymerization process, copolymerizable active surfactants are added in a concentration which can vary between 0.1 and 3% of the monomeric dry matter of the emulsion, and c) the content of polymeric material is adjusted to a concentration of 30-40% either during the polymerization process. during or after distilling off the excess solvent azeotropically. Process for the preparation of high-molecular-weight water-soluble polymers according to Claim 1, characterized in that vinyl derivatives having the general formula ROI II CH 2 = C - C - O (CH 2 CH 2 O) n H in which R is a hydrogen atom or a C The C 1-4 alkyl group and n may range from 2 to 50, or sulfonated vinyl derivatives of the general formula? CH 3 = C - (CH 2) n --O - (CH 2) m.CH.CH 2 SO 3 Na n 85586 wherein R is a hydrogen atom or a C 1 -C 8 chain linear alkyl group, and the symbols n and m may have values between 1 and 3. Process for preparing high molecular weight water-soluble polymers according to Claims 1 and 2, characterized in that the water-soluble polymer can contain the following monomers: on the one hand acrylamide and on the other hand acrylic acid and its salts, methacrylamide, methacrylic acid and its salts; methyl acrylate, ethyl acrylate and propyl acrylate; methyl and ethyl methacrylate; hydroxyethyl acrylate and hydroxyethyl methacrylate; acrylonitrile, styrene, 2-acrylamide-2-methylpropanoic acid and its salts, vinyl pyrrolidine and vinyl methyl ether, dimethylaminoethyl methacrylate; d imetyl amine is acrylate; dietyy1iaminoetyy1i-metakry1aatti; diethylaminoethyl 1-acrylate; as well as quaternary derivatives of these compounds from their reaction with methylene chloride or methyl sulfate; 3- (methylacrylamide) -propyltrimethylammonium chloride • · 1 · · 12 8 5 586