METHOD OF PREPARATION OF CATIONIC POLYMERS WITH REDUCED HALIDES CONTENT

Abstract

The present invention relates to a polymer preparation method for preparing water-soluble cationic polymers P1 wherein the halides content is reduced, as well as to the use of these polymers as additives in compositions that are based on inorganic mineral binders or in the treatment of aqueous open, semi-closed, or closed circuits.

Claims

1. A polymer preparation method for preparing an aqueous solution of water-soluble cationic polymers P1 wherein the halides content is lower than 10% by weight of the polymer, the viscosity at 25 C. is lower than 200 cps, said viscosity being determined for an aqueous solution of polymers P1 concentrated at 50% by weight, and the cationic charge density is greater than or equal to 4 meq.g .sup.1, characterized in that it comprises the following successive steps: a) adding, at a temperature comprised between 0 C. and 120 C., of at least one compound of formula (I) to an aqueous solution of at least one water soluble cationic polymer P2 wherein the halides content is greater than 10% by weight of the polymer, the viscosity at 25 C. is lower than 200 centipoise cps, said viscosity being determined for an aqueous solution of polymers P2 concentrated to 50% by weight, and the cationic charge density being greater than or equal to 4 meq.g .sup.1, the compound of formula (I) being defined by the formula: R.sup.1COO.sup.y.sub.1.sup.+, wherein: R.sup.1 represents a hydrogen atom or a saturated alkyl chain, either linear or branched, comprising from 1 to 8 carbon atoms, that may contain at least one nitrogen atom and/or oxygen atom, said chain may be substituted by 1 to 4 carboxylate functional groups of formula COR; Y.sub.1.sup.+ represents an alkali metal cation, an ammonium ion of formula R.sup.2NH.sub.3.sup.+ or a quaternary ammonium of formula R.sup.3N.sup.+(R.sup.4)(R.sup.5)(R.sup.6); R represents an OH group or a group O.sup.Y.sub.2.sup.+; Y.sub.2.sup.+ represents an alkali metal cation or an ammonium ion of formula R.sup.2NH.sub.3.sup.+; R.sup.2 represents a hydrogen atom or a saturated alkyl chain, either linear or branched, comprising from 1 to 4 carbon atoms ; and R.sup.3, R.sup.4, R.sup.5 and R.sup.6 represent, independently of each other, a saturated alkyl chain, either linear or branched, comprising from 1 to 4 carbon atoms; in order to obtain a mixture; b) agitation of the mixture obtained in step a) for at least 5 minutes in order to obtain a stirred mixture; c) decreasing of the temperature of the stirred mixture obtained at the end of step b) at a temperature comprised between 10 C. and 50 C. in order to obtain a cooled mixture; and d) liquid/solid separation of the cooled mixture obtained at the end of step c) in order to obtain an aqueous solution of cationic polymers P1.

2. A method according to claim 1, wherein the water-soluble cationic polymers P1 are characterised by a cationic charge density greater than or equal to 5 meq.g

3. A method according to claim 1, in which the water-soluble cationic polymers P1 are characterised by a content by weight of insoluble compounds lower than 2% relative to the total weight of the polymer.

4. A method according to claim 1, in which in step a) the ratio of the number of anionic charges of the compound of formula (I) to the number of cationic charges of the water-soluble cationic polymer P2 is comprised between 0.2:1 and 5:1.

5. A method according to claim 1, in which the water soluble cationic polymer P2 is characterised by a cationic charge density greater than or equal to 6 meq.g.sup.1.

6. A method according to claim 1, in which the compound of formula (I) is selected from among sodium formate, potassium formate, sodium acetate and potassium acetate.

7. A method according to claim 1, in which liquid/solid separation step d) is a decantation or filtration process, preferably a filtration process.

8. A method according to claim 1, in which the water soluble cationic polymer P2 is derived from the polymerisation of at least one monomer of such type as diallyldialkyl ammonium halide.

9. A method according to claim 1, in which the water soluble cationic polymer P2 is derived from the polymerization of at least diallyl dimethyl ammonium chloride.

10. A method according to claim 1, in which the water soluble cationic polymer P2 is a polymer that is derived from the polycondensation of at least one epihalohydrin and at least one secondary amine

11. A method according to claim 1, in which the water soluble cationic polymer P2 is a polymer that is derived from the polycondensation of epichlorohydrin and dimethylamine

12. A method according to claim 11, in which the stoichiometric ratio between dimethylamine and epichlorohydrin is comprised between 1:0.99 and 1:0.80.

13. A method according to claim 1, in which the water-soluble cationic polymers P1 are characterized by a cationic charge density that is greater than or equal to 6 meq.g.sup.1.

14-15. (canceled)

16. Composition based on inorganic mineral binders or on gypsum derivatives comprising a water soluble cationic polymer P1 that is likely to be obtained by the method according to claim 1 as additives.

17. Method for the treatment of open, semi-closed, or closed aqueous circuits comprising the use of a water soluble cationic polymer P1 that is likely to be obtained by the method according to claim 1.

18. Method for moderating the effect of clays in a composition based on inorganic mineral binders or on gypsum derivatives comprising the use of a water soluble cationic polymer P1 that is likely to be obtained by the method according to claim 13.

Description

EXAMPLES

[0111] Example 1 Preparation of a Polymer P1 Characterized by a Chlorides Content Lower than 10% by Weight of the Polymer and Obtained as a Result of the Polycondensation of Epichlorohydrin and Dimethylamine

[0112] In a 1 litre reactor equipped with a jacket, a condenser, a mechanical agitation mechanism and a temperature sensor probe, the following were added: 272 g of dimethylamine at a concentration of 60% by weight (source: Sigma Aldrich) and 331 g of water. Thereafter, 319 g of epichlorohydrin (source: Sigma Aldrich) was added drop-by-drop over a period of 3 hours, with the temperature being maintained at 70 C.-80 C.

[0113] Approximately 80 g of water at 50 C. was then added to the mixture in order to adjust the concentration of the polymer so formed to 50% by weight.

[0114] The polycondensation product obtainedknown as polymer Ais characterized by a cationic charge density equal to 7 meq.g.sup.1, a viscosity at 25 C. of 30 cps, this viscosity being determined for an aqueous solution of polymer A concentrated to 50% by weight, and a chlorides content of 25% by weight of the polymer; these values being measured according to the protocols as previously defined.

[0115] 500 g of the polymer A were introduced into a thermostatically controlled 1-litre reactor equipped with a jacket, a magnetic agitator, a condenser, and a temperature sensor probe prior to 183 g of potassium acetate (source: Sigma Aldrich) being introduced therein. The reaction mixture was heated to 80 C., and maintained under agitation for a period of 2 hours, then cooled to 25 C. and filtered with a centrifugal extractor RC30 (supplier: Robatel) equipped with a filtre of 6 m porosity, made of polypropylene and that makes it possible to obtain a polycondensation productknown as polymer Bcontaining 0.5% of insolubles.

[0116] Polymer B is characterized by a viscosity at 25 C. of 35 cps, this viscosity being determined for an aqueous solution of polymer B concentrated to 49.6% by weight, a cationic charge density of 6.2 meq.g.sup.1, and a chlorides content equal to 8% by weight of the polymer; these values being measured according to the protocols as previously defined here above.

[0117] Example 2: Preparation of a Polymer P1 of Diallyl Dimethyl Ammonium Chloride Characterized by a Chlorides Content Cower than 10% by Weight of the Polymer.

[0118] In a 1 litre reactor equipped with a jacket, a condenser, a mechanical agitation mechanism and a temperature sensor probe, the following were added: 95 g of water, 135 g of diallyl dimethyl ammonium chloride (DADMAC) at a concentration of 64% by weight in water (source: SNF) and 17 g of sodium hypophosphite at a concentration of 50% by weight in water. Solutions of sodium hypophosphite and sodium persulfate were prepared by mixing respectively 13 g of water with 13 g of sodium hypophosphite (source: Sigma Aldrich) and 100g of water with 13g of sodium persulphate (source: Sigma Aldrich). 536 g of DADMAC (concentration 64% by weight in water), as well as solutions of sodium hypophosphite and sodium persulfate were gradually added into the 1 litre reactor, over a period of 2 hours.

[0119] The homopolymer of DADMAC obtainedknown as polymer Cis characterized by a charge density of 6 meq.g.sup.1, a viscosity at 25 C. of 52 cps, this viscosity being determined for an aqueous solution of polymer C concentrated to 51% by weight, and a chlorides content of 22% by weight of the polymer; these values being measured according to the protocols as previously defined here above.

[0120] Then, 500 g of polymer C were introduced into a thermostatically controlled 1-litre reactor equipped with a jacket, a magnetic agitator, a condenser, and a temperature sensor probe, in which 152 g of potassium acetate was added. The reaction mixture was heated to 85 C., then maintained under agitation for a period of 4 hours before being cooled to 30 C. The resulting mixture obtained was filtered with a centrifugal extractor RC30 (supplier: Robatel) equipped with a filtre of 6 m porosity, made of polypropylene that makes it possible to obtain a polymer product of DADMACknown as polymer Dcontaining 1% of insolubles.

[0121] Polymer D is characterized by a viscosity at 25 C. equal to 53 cps, this viscosity being determined for an aqueous solution of polymer D concentrated at 50% by weight, a cationic charge density of 5.4 meq.g.sup.1 and a chlorides content equal to 7% by weight of the polymer; these values being measured according to the protocols as previously defined here above.

[0122] Example 3: Use of Water-Soluble Cationic Polymers as an Agent for Clay Moderation in a Flow Test Concrete (Slump Test)

[0123] The performance of the water-soluble cationic polymers P1 of the present invention is evaluated in the flow of a cementitious composition (according to the standard ASTM C1611).

[0124] The slump test consists of positioning a cone at the center of a plate, on which is drawn a circle, filling the cone (open at its two bases) with the composition in respect of which are to be measured the flow, the screeding and the demoulding. Concrete thus flows more or less based on its rheology. The spreading is the average of the distances along two axes that are perpendicular between the centre of the circle and the end of the position formed by the poured concrete.

[0125] The cementitious formulation is composed of

[0126] Cement (source: Lafarge) dosed in proportions of 445 kg/m.sup.3

[0127] Sand (normalised, with density of 1485 kg/m.sup.3) dosed in proportions of 885 kg/m3.

[0128] Bentonite clay

[0129] Water

[0130] Polycarboxylic acid superplasticiser (Floset SH7 from the company SNF)

[0131] Several compositions (1 to 4) were prepared by mixing sand, cement, clay, water, a superplasticiser and a water-soluble cationic polymer for a period of 5 minutes. The proportions of the different components are summarised in Table 1, as well as the results of the flow test of the composition.

TABLE-US-00001 TABLE 1 Characteristics of four compositions comprising the water-soluble cationic polymers and results of the spreading test of the concrete. Composition 1 2 3 4 Cement (g) 450 450 450 450 Water (g) 202.5 202.5 202.5 202.5 Sand (g) 1350 1350 1350 1350 Clay (g) 9.45 9.45 9.45 9.45 Superplasticiser 7.5 7.5 7.5 7.5 (g) Type of Polymer B Polymer D CMA-2 of patent Cationic (according (according to US2015/0065614 Polymer to the the invention) (comparative) invention) Cationic 0 0.189 0.199 0.189 Polymer (g) Spreading of 240 310 320 310 the concrete (mm)

[0132] Based on the Table 1, the water-soluble cationic polymers make possible a gain of about 30% with respect to the flow of concretes. Cationic polymers with reduced content levels of halides (polymers B and D) and derived from the method of the invention have performance levels that are similar or superior to the cationic polymers of the state of the art as reflected in the document US 2015/0065614.

[0133] According to the examples of US 2015/0065614, the polymer CMA-2 is characterized by a cationic charge density of 7.2 meq/g, a chloride content of 25% by weight of the polymer and a viscosity of 8.4 cps, this viscosity being determined for an aqueous polymer solution concentrated to 50% by weight.

[0134] Thus, the decrease in the halides content in the cationic water-soluble polymer does not result in the loss of activity of this polymer.

[0135] Example 4: Test of the Corrosion Induced by Various Vationic Polymers

[0136] The test consists of the immersing of metal cuttings of various different grades/alloys into the solutions of cationic polymers. A qualitative assessment of the corrosion is carried out on the basis of a scale ranging from 0 to 10:

[0137] 0=No corrosion observed

[0138] 3=Some points of corrosion (pitting-type) were observed

[0139] 5=Moderate attack of the entire metal cutting

[0140] 7=Severe attack of the entire metal cutting

[0141] 10=Complete attack of the entire metal cutting.

[0142] The metal cuttings have the following dimensions: length: 100 mm, width: 30 mm, thickness: 1 mm. Before use, the metal cuttings were cleaned in order to remove any solids and were washed with acetone in order to remove any oil residue on their surface. They were then immersed in a vessel containing an aqueous solution of a cationic polymer in a concentration of 50% by weight so as to remain immersed therein for a period of 14 days at 30 C.

[0143] The results of this corrosion test conducted on two different steels and in the presence of four different water-soluble cationic polymers (comparative and according to the invention) in solution are presented in Table 2.

TABLE-US-00002 TABLE 2 Evaluation of the corrosion induced by various different cationic polymers % by weight of Evaluation chlorides in of the Cationic Polymer Grade of Steel the polymer corrosion Polymer B (comparative) Carbon Steel 8 4 Polymer D (according to the Carbon Steel 7 4 invention) CMA-2 (US 2015/0065614) Carbon Steel 26 8 (comparative) Polymer C (comparative) Carbon Steel 22 7 Polymer B (according to the Stainless Steel 8 1 invention) 304L Polymer D (according to the Stainless Steel 7 1 invention) 304L CMA-2 (US 2015/0065614) Stainless Steel 26 5 (comparative) 304L

[0144] Table 2 shows that on a carbon steel grade, the water-soluble cationic polymers P1 derived from the method according to the invention (polymers B and D) induced a level of corrosion that was reduced, and in comparison, was two times less than that with the polymers that present a higher halides content (polymers C and CMA-2).

[0145] Thus, the use of the polymers P1 according to the invention clearly induces a reduced level of corrosion in comparison to the use of polymers of the state of the art.

[0146] The same observations may be made with regard to the use of cationic polymers on a grade of stainless steel 304L.