MXPA01001883A - Method for producing copolymers by radical polymerisation - Google Patents

Abstract

The invention relates to a method for producing copolymers by radical polymerisation of a) 5 to 95 wt.%of a monomer of formula (I), b) 95 to 5 wt.%of a monomer of formula (II), wherein R1 and R2 represent H, C1-C3-alkyl, R3=H, C1-c6-alkyl and n=1 to 3 respectively and c) 0 to 40 wt.%of another fully or partially water-soluble monomer. The inventive method is characterised in that the polymerisation is carried out in an aqueous medium.

Description

Procedure for obtaining copolymers by radical-initiated polymerization Description The invention relates to a process for obtaining copolymers by polymerization initiated by radicals of a) 5 to 95% by weight of a monomer of the formula I -Rl H2C = C • N R2 I (I) c = or R3 b) 95 to 5% by weight of a monomer of the formula II Rl wherein R1 and R2 are, respectively, H, C? -C3-alkenyl R3 = H, C? C6-alkyl and n = 1 to 3 c) O to 40% by weight of another monomer completely or partially soluble in water, process which is characterized in that the polymerization is carried out in an aqueous medium, as well as to copolymers obtained according to this process and their use as inhibitors of gas hydrates.

From WO 96/41785 a method for the inhibition of hydrate formation is known, ie methods that prevent the generation of gas hydrates in media, which contain gas and water molecules.

In this known process, copolymers, which consist of N-methyl-N-vinylacetamide and an N-vinyl lactam, are used as gas hydrate inhibitors. The copolymers are prepared by polymerization initiated by radicals in benzene or in alcohols. However, these organic solvents are problematic in obtaining and handling the resulting copolymer solution. They must be eliminated in certain cases before being used as inhibitors of gas hydrates, which requires energy and time.

From Polymer Journal, Vol. 17, No. 1, pp. 143-152 (1985), it is known that vinylpyrrolidone can be obtained by polymerization initiated by radicals in organic solvents or also in H2, where the polymers obtained in H20 are sensitive to oxidation.

The object of the present invention is to avoid the aforementioned handling disadvantages.

This object is achieved by carrying out the polymerization in an aqueous medium.

The monomers of the formula I are preferably used in amounts of 20 to 80% by weight, the monomers of the formula II, preferably in amounts of 80 to 20% by weight. Preferably, in formula I, R2 and R3 = methyl and R1 mean in both monomers I and II = hydrogen. The preferred monomer of formula I is N-methyl-N-vinylacetamide, the preferred monomer of formula II is vinylcaprolac-tama.

As another comonomer c) copolymerizable, a comonomer complete or kimi readily soluble in water can be used.

Comonomers c) which are preferably used are, for example, carboxylic esters and their esters, anhydrides, amides, nitriles, esters or vinyl ethers. Mentioned are especially: acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylate. of hydroxyisobutyl, hydroxyisobutyl methacrylate, monomethyl malonate, dimethyl maleate, monoethylene maleate, diethyl maleate, mono-ethyl maleate, diethylene maleate, maleimides, ethylhexyl acrylate, 2-ethylhexyl methacrylate, acrylamide , methacrylamide, N-dimethylacrylamide, N-tere. -butylacrylamide: N-isopropylmethacrylamide, methacryloylpyrrolidine, acrylonitrile, methacrylonitrile, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethylmethacrylate, as well as the salts of the last mentioned monomers with acids carboxylic or mineral acids, as well as quaternary products. As vinyl esters are mentioned, vinyl acetate, vinyl propionate, as well as the vinyl esters of a synthetic fatty acid with 10 carbon atoms ("versatic-10" acid) or with 9 carbon atoms ("versatic acid-9"). "), both of which are obtained in commerce (eg from Shell). Vinyl ethers include vinyl -C?-C4-alkyl ether, especially, the vinyisobutyl ether. In addition, acrylamidoglycolic acid, vinyl sulphonic acid, allyl sulfonic acid, methallylsulfonic acid, styrenesulfonic acid, (3-sulfopropyl) acrylate, (3-sulphopropyl) methacrylate and acrylamidomethylpropanesulfonic acid, as well as monomers containing gruopos are suitable as monomers. of phosphonic acid, such as, for example, Si vinyl phosphate, allyl phosphate and acrylamidemethanepropanephosphonic acid. Naturally, it is also possible to use mixtures of the aforementioned monomers, eg mixtures of acrylate and vinyl acetate, mixtures of different acrylates, mixtures of acrylates and acrolamide or mixtures of acrylamide and acrylate. hydroxyethyl.

It is preferred, especially acrylamide and acrylates.

The aqueous medium can consist exclusively of H20 or be a mixture of H20 and alcohol, especially CH3OH or C2H5OH.

The initiation is carried out with water-soluble initiators in amounts of 0.1 to 5% by weight, with respect to the monomer, most preferably 0.2 to 2% by weight.

As the water-soluble initiator, hydrogen peroxide is especially preferred, while traces of Cu (II) salts are introduced into the reaction mixture from monomer and water at the same time.

The pH value during the polymerization varies between 4 and 9, most preferably between 6 and 8. The pH value during (all) polymerization is regulated by the addition of aqueous acids or liquors. Generally, it suffices to add a bleach, with an aqueous solution of ammonia being preferred, eg at 10%.

The K values of the polymers obtained according to the invention (determined according to Fikentscher, Cellulose Chemie, 13, 58-64, 71-74, 1932, 1% aqueous solution, 20 ° C, K = k-103) amount to 10 to 100, preferably 15 to 45. The molecular weights of the polymers (Mw) amount to 2000 to 800000, preferably 5000 to 100,000.

The copolymers of the invention can be used as inhibitors of gas hydrates, as described in WO 96/41785. For this purpose, the polymers are added in the usual amounts, which the expert adapts to the respective conditions.

The polymers used according to the invention can be used for the purpose of inhibiting gas hydrate together with other products. These other products can be other polymers, such as hydroxyalkylcelluloses, polyvinylpyrrolidone or polyvinylcaprolactam, preferably in amounts of 1 to 3.5% by weight, based on the weight of the entire liquid system, but also alcohols, such as methanol, ethanol or ethylene glycol or water-soluble salts, preferably in an amount of 10 to 30% by weight, based on the weight of the entire liquid system.

Eg emplos Example of obtaining Initial charge: 1125.00 g of demineralised water 300.00 g of vinylcaprolactam 200.00 g of N-vinylmethylacetamide Entry 1: 8.30 g of hydrogen peroxide (30%) Entry 2: 0.50 g of copper (II) chloride (0.01%) entry 3: xx g of ammonia water (at 5%) Input 4: 0.50 g of copper (II) chloride (0.1%) input 5: 5.00 g of hydrogen peroxide (30%) Method The initial charge is rinsed with nitrogen and heated to an internal temperature of approx. 80 ° C. At an indoor temperature of approx. 78 ° C is added input 1, then input 2. With input 3 the pH value is maintained throughout the polymerization period at pH = 7.0. After a polymerization time of 3.5 hours, the inputs 4 and 5 are added. After the inputs 4 and 5, the polymerization is continued for 4 hours at an internal temperature of approx. 80 ° C. Then it is cooled to room temperature. Characterization solid content 30% by weight K value 34 (1% in water) pH value 6 Table corresponds to the liquid state x corresponds to the freezing temperature In comparison 1 no polymer is added. All polymers in water VIMA: N-methyl-N-vinylacetamide; VCap: vinylcaprolactam The "freezing temperature" is measured according to the "Ball-Stop" method, in analogy to the test method described in Example 1 of W095 / 32356.

This method refers to the freezing points to be examined of water / THF mixtures by the addition of different polymers (checking the formation of hydrate), which are frozen at 0.5% in a water / THP mixture (81/19 % in weigh).

To determine this freezing point of different polymer mixtures / (water / THF) the following devices and reagents are needed: water / THF mixture (81/19% by weight) Julabo F 18 tempering bath with cooling mixture water / ethylene glycol (5/1) Multifix-Constant stirrer test tube holder (5 ml) stainless steel pellets for a better intermixed in the test tube A 0.5% solution of the polymer to be examined is prepared in water / THF (81/19). The test tube is filled in 2/3, stainless steel pellets are incorporated, closed and fixed in the support for the test tubes. The measurement is started at 4 ° C bath temperature and a revolution speed of 20 rpm and the temperature is decreased by 0.5 ° C per hour until the sample is frozen or the steel pellets in the test tube they no longer move, or a temperature of 0 ° C has been reached. Parallel to each measurement, a witness test is carried out.

Claims (11)

Claims

1. Process for obtaining copolymers by polymerization initiated by radicals of a) 5 to 95% by weight of a monomer of the formula I • Rl H2C- • N- R2 (I) O R3 b) 95 to 5% by weight of a monomer of the formula II ^ 1 where R 1 and R 2 are, respectively, H, C 3 -C 3 -alkyl R 3 = H, C α -6-alkyl and n = 1 to 3 c) 0 to 40% by weight of another monomer completely or partially soluble in water, which process is characterized in that the polymerization is carried out in an aqueous medium,

2. Process according to claim 1, characterized in that 20 to 80% by weight of monomer a) and 80 to 20% by weight of monomer b) are used.

3. Process according to claim 1, characterized in that the monomer b) is vinylcaprolactam.

4. Process according to claim 1, characterized in that R2 and R3 in monomer a) are methyl.

5. Process according to claim 1, characterized in that R1 in monomers a) and / or b) is hydrogen.

6. Process according to claim 1, characterized in that the aqueous medium is water.

The method according to claim 1, characterized in that a poylimerization initiation system containing H2? 2 is employed.

8. Copolymers obtained according to the procedure of claim 1.

9. Copolymerized according to claim 8, characterized in that they have hydroxyl end groups.

10. Copolymers according to claim 8, characterized in that they have a K value of 10 to 100. 35

11. Use of the copolymers according to claim 8 as gas hydrate inhibitors. 10 15 20 25 30 35 SUMMARY OF THE INVENTION. Process for obtaining copolymers by polymerization initiated by radicals of a) 5 to 95% by weight of a monomer of the formula I Rl H2C = C • N R2 (I) c = or R3 b) 95 to 5% by weight of a monomer of the formula II Rl H2C = (II) (CH2) n wherein R 1 and R 2 represent, respectively H, C 3 -C 3 alkyl R 3 = H, CiA-alkyl and n = 1 to 3 c) 0 to 40% by weight of another monomer completely or partially soluble in water, process which is characterized in that the polymerization is carried out in an aqueous medium.