Method of milling minerals in the presence of a poly (itaconate)

Abstract

The invention relates to a method for producing particles of mineral material comprising grinding of at least one mineral material in the presence of water. The grinding according to the invention is carried out in the presence of at least one polymer obtained by a radical polymerization reaction of a partial sodium salt of itaconic acid and partial decarboxylation of the polymer obtained followed by partial or total neutralization of the decarboxylated polymer. The invention also relates to an aqueous composition comprising particles of ground mineral material and such a polymer, in particular a mass-loading composition for the production of paper or a paper-coating-colour composition.

Claims

1. A method for producing mineral material particles, the method comprising grinding at least one mineral material in the presence of water and at least one polymer so that the at least one mineral material has a particle size of 0.05-50 μm, wherein the at least one polymer is obtained by: performing a radical polymerization reaction of a partial sodium salt of itaconic acid in the presence of sodium hypophosphite, at a temperature above 50° C. to obtained an itaconic acid polymer; partially decarboxylating the itaconic acid polymer to obtain a decarboxylated polymer; and partially or totally neutralizing the decarboxylated polymer with a derivative comprising sodium to obtain the at least one polymer.

2. The method according to claim 1, wherein only one mineral material or two or three mineral substances are used; or the mineral material is synthetic or of natural origin.

3. The method according to claim 1, wherein the polymerization reaction is carried out: in water, in a solvent, alone or in a mixture with water; or in the presence of at least one radical generating compound; or in the presence of at least one chain transfer agent.

4. The method according to claim 1, wherein: the first acidity of itaconic acid of the partial sodium salt of itaconic acid is partially salified and the second acidity of itaconic acid of the partial sodium salt of itaconic acid is not salified; or the first acidity of itaconic acid of the partial sodium salt of itaconic acid is totally salified and the second acidity of itaconic acid of the partial sodium salt of itaconic acid is not salified; or the first acidity of itaconic acid of the partial sodium salt of itaconic acid is totally salified and the second acidity of itaconic acid of the partial sodium salt of itaconic acid is partially salified.

5. The method according to claim 1, wherein the polymer: has a weight average molecular mass M.sub.w, measured by CES, of less than 20,000 g/mol; or has a weight average molecular mass M.sub.w, measured by CES, of greater than 1,000 g/mol or greater than 1,200 g/mol; or has an IP polymolecularity index of less than 4.

6. The method according to claim 1, wherein: from 5 to 90 mol % of the second acidity of the itaconic acid polymer is decarboxylated.

7. The method according to claim 1, wherein: the itaconic acid polymer is totally neutralized or neutralized to 40 mol %; or the itaconic acid polymer is neutralized with sodium hydroxide, sodium carbonate, or sodium bicarbonate.

8. The method according to claim 1, wherein: the aqueous suspension of the at least one mineral material having a median particle size of 1.5±0.15 μm has a cationic demand less than or equal in absolute value to 5μ-equivalent per g of suspension of particles in water at a concentration of 65 to 75% by weight; or the aqueous suspension of the at least one mineral material with a median particle size of 0.7±0.15 μm has a cationic demand less than or equal in absolute value to 13μ-equivalent per g of suspension of particles in water at a concentration of 65 to 75% by weight.

9. An aqueous composition, comprising mineral material particles produced by the method of claim 1.

10. The composition according to claim 9, wherein: the aqueous suspension of the at least one mineral material having a median particle size of 1.5±0.15 μm has a cationic demand less than or equal in absolute value to 5μ-equivalent per g of suspension of particles in water at a concentration of 65 to 75% by weight; or the aqueous suspension of the at least one mineral material with a median particle size of 0.7±0.15 μm has a cationic demand less than or equal in absolute value to 13μ-equivalent per g of suspension of particles in water at a concentration of 65 to 75% by weight.

11. The composition according to claim 9, further comprising at least one cellulosic material and optionally at least one additive.

12. A method for producing a paper-mass-loading composition or a paper-coating colour composition, the method comprising grinding at least one mineral material in the presence of water and at least one polymer to form an aqueous suspension of particles of the at least one mineral material, wherein the at least one mineral material has a particle size of 0.05-50 pan, wherein the at least one polymer is obtained by: performing a radical polymerization reaction of a partial sodium salt of itaconic acid in the presence of sodium hypophosphite, at a temperature above 50° C., to obtained an itaconic acid polymer; partially decarboxylating the itaconic acid polymer to obtain a decarboxylated polymer; and partially or totally neutralizing the decarboxylated polymer with a derivative comprising sodium, to obtain the at least one polymer.

13. A grinding aid for particles of mineral material, the grinding aid comprising a polymer that is obtained by: performing a radical polymerization reaction of a partial sodium salt of itaconic acid in the presence of sodium hypophosphite, at a temperature above 50° C., to obtained an itaconic acid polymer; partially decarboxylating the itaconic acid polymer to obtain a decarboxylated polymer; and partially or totally neutralizing the decarboxylated polymer with a derivative comprising sodium, to obtain the at least one polymer.

14. A method, comprising producing paper with the aqueous composition of claim 10.

15. The method according to claim 14, wherein the aqueous composition includes at least one cationic agent whose amount is reduced compared to a conventional papermaking process.

Description

EXAMPLE 1

(1) From itaconic acid partially neutralized with soda added slowly, with stirring and at a controlled temperature, then polymerized by heating in water and stirring in the presence of sodium hypophosphite and tertiobutyl hydroperoxide or hydrogen peroxide, and finally partially decarboxylated by heating under reflux in water, a polymeric solution (P1-1) of partially decarboxylated sodium polyitaconate having a concentration of 40% by weight of polymer and a pH of 9 is produced (described method in the examples of WO 2015-100412).

(2) Then, a suspension of calcium carbonate particles (S1-1) is produced by grinding coarsely crushed calcite rock from the region of Orgon, France (BL 200, Omya) in the presence of polymer (P1-1) (0.26% by dry weight of polymer relative to the amount of calcite rock) as grinding aid agent. The obtained suspension has a solid mineral content of 75±1% by weight. Grinding conditions are adjusted in order to obtain a suspension of calcium carbonate particles the median diameter of which is 1.5±0.15 μm.

(3) Similarly, suspensions of calcium carbonate particles (S1-2) to (S1-4) are produced by means of polymer solutions (P1-2) to (P1-4) of other partially decarboxylated sodium polyitaconates. Finally, a comparative suspension of calcium carbonate particles (S1-C) is produced using a known polymeric solution of sodium polyacrylate (P1-C) (Rheosperse 3206, Coatex) used at the same dose and the same conditions.

(4) The characteristics of polymers (M.sub.w, IP and decarboxylation rate of the second acidity in mol %) and suspensions (d.sub.50, Brookfield viscosity at 100 rpm measured at 25° C. and absolute value of Mütek charge) are shown in table 1.

(5) TABLE-US-00001 TABLE 1 Polymer (P1-1) (P1-2) (P1-3) (P1-4) (P1-C) M.sub.w (g/mol) 2,140 2,200 2,740 4,500 4,540 IP 1.73 1.72 1.82 2.01 2.12 decarboxylation 81 63 75 80 / rate (%) suspension (S1-1) (S1-2) (S1-3) (S1-4) (S1-C) d.sub.50 (μm) 1.55 1.62 1.48 1.61 1.61 viscosity (mPa .Math. s) 150 270 260 305 120 | Mütek charge | (μeq/g) 4.6 5.0 4.3 5.0 6.5

(6) It is observed that the grinding aid agents according to the invention make it possible to produce suspensions of low-viscosity ground calcium carbonate mineral filler with a median diameter of 1.5±0.15 μm. The cationic demand of these suspensions of mineral charge is less than or equal in absolute value to 5μ-equivalents per gram of suspension of particles in water at a concentration of 75% by weight.

EXAMPLE 2

(7) In a similar manner to example 1, suspensions of calcium carbonate particles (S2-1) and (S2-2) are produced by grinding coarsely crushed calcite rock originating from the region of Orgon, France (BL 200, Omya) in the presence of polymeric solutions (P1-1) and

(8) (P1-3) at 40% by weight of polymer and pH of 9 (0.6% by dry weight of polymer in relation to the amount of rock calcite) as grinding aid agents. The obtained suspensions have a solid mineral content of 75±1% by weight. Grinding conditions are adjusted in order to obtain a suspension of calcium carbonate particles the median diameter of which is 0.7±0.15 μm.

(9) Under the same conditions, a comparative suspension of calcium carbonate particles (S2-C) is also produced using a polymer solution of a sodium polyacrylate (P1-C).

(10) The characteristics of polymers (M.sub.w, IP and decarboxylation rate of the second acidity in mol %) and suspensions (d.sub.50, Brookfield viscosity at 100 rpm measured at 25° C. and absolute value of Mütek charge) are shown in table 2.

(11) TABLE-US-00002 TABLE 2 polymer (P1-1) (P1-3) (P1-C) M.sub.w (g/mol) 2,140 2,740 4,540 IP 1.73 1.82 2.12 decarboxylation rate (%) 81 75 / suspension (S2-1) (S2-2) (S2-C) d.sub.50 (μm) 0.74 0.70 0.74 viscosity (mPa .Math. s) 320 590 150 | Mütek charge | (μeq/g) 12.3 11.8 15.6

(12) Once again, it is found that the grinding aid agents according to the invention make it possible to produce suspensions of low viscosity ground calcium carbonate mineral filler the median diameter of which is 0.7±0.15 μm. The cationic demand for these suspensions of mineral filler particles is less than or equal in absolute value to 13μ-equivalents per gram of suspension of particles in water at a concentration of 75% by weight.

EXAMPLE 3

(13) According to the method of example 1, from itaconic acid partially neutralized with sodium hydroxide and then polymerized in water in the presence of sodium hypophosphite and finally partially decarboxylated, a polymeric solution (P3-1) of partially decarboxylated sodium polyitaconate having a concentration of 42% by weight of polymer and a pH of 5.5.

(14) Then, a suspension of calcium carbonate particles and lime particles (S3-1) is produced by grinding coarsely crushed calcite rock from the region of Orgon, France (BL 200, Omya) and lime hydrated (Supercalco 95—Carmeuse) (ratio calcium carbonate/lime hydrated to 100/0.1 by weight) in the presence of polymer (P3-1) (0.26% by dry weight of polymer in relation to the amount of rock calcite and lime) as a grinding aid. The suspension obtained has a solid mineral content of 75±1% by weight. Grinding conditions are adjusted in order to obtain a suspension of calcium carbonate particles the median diameter of which is 1.5±0.15 μm.

(15) The characteristics of the polymer (M.sub.W, IP and decarboxylation rate of the second acidity in mol %) and of the suspension (d.sub.50, Brookfield viscosity at 100 rpm measured at 25° C. and absolute value of Mütek charge) are shown in Table 3.

(16) TABLE-US-00003 TABLE 3 polymer (P3-1) M.sub.w (g/mol) 2,000 IP 1.64 decarboxylation rate (%) 69 suspension (S3-1) d.sub.50 (μm) 1.56 viscosity (mPa .Math. s) 105 |Mütek charge| (μeq/g) 4.5

(17) It is observed that the grinding aid agent according to the invention makes it possible to produce a suspension of low viscosity mineral fillers the median diameter of which is 1.5±0.15 μm. The cationic demand of this suspension is less than or equal in absolute value to 5μ-equivalent per gram of suspension of particles in water at a concentration of 75% by weight.

EXAMPLE 4

(18) In a similar manner to example 1, a suspension of calcium carbonate particles (S4-1) is produced by grinding coarsely crushed calcite rock originating from the region of Orgon, France (BL 200, Omya) in the presence a polymer (P4-1) at 40% by weight of polymer and a pH of 11.8 (0.26% by dry weight of polymer relative to the amount of calcite rock) as a grinding aid. The obtained suspension has a solid mineral content of 75±1% by weight. Grinding conditions are adjusted in order to obtain a suspension of calcium carbonate particles the median diameter of which is 1.5±0.15 μm.

(19) The characteristics of the polymer (M.sub.w, IP and decarboxylation rate of the second acidity in mol %) and of the suspension (d.sub.50, Brookfield viscosity at 100 rpm measured at 25° C. and absolute value of Mütek charge) are shown in Table 4.

(20) TABLE-US-00004 TABLE 4 polymer (P4-1) M.sub.w (g/mol) 3,600 IP 2.00 decarboxylation rate (%) 70 suspension (S4-1) d.sub.50 (μm) 1.56 viscosity (mPa .Math. s) 191 |Mütek charge| (μeq/g) 4.7

(21) It is observed that the grinding aid agent according to the invention makes it possible to produce a suspension of low viscosity mineral fillers the median diameter of which is 1.5±0.15 μm. The cationic demand of this suspension is less than or equal in absolute value to 5μ-equivalent per gram of suspension of particles in water at a concentration of 75% by weight.

EXAMPLE 5

(22) In a similar manner to example 1, suspensions of calcium carbonate particles (S5-1) and (S5-2) are produced by grinding coarsely crushed calcite rock originating from the region of Orgon, France (BL 200, Omya) in the presence of polymeric solutions (P5-1) and

(23) (P5-2) at 40% by weight of polymer and pH of 9 (0.20% by dry weight of polymer in relation to the amount of rock calcite) as grinding aid agents. The obtained suspensions have a solid mineral content of 65±1% by weight. Grinding conditions are adjusted in order to obtain a suspension of calcium carbonate particles the median diameter of which is 1.5±0.15 μm.

(24) The characteristics of polymers (M.sub.w, IP and decarboxylation rate of the second acidity in mol %) and suspensions (d.sub.50, Brookfield viscosity at 100 rpm measured at 25° C. and absolute value of Mütek charge) are shown in table 5.

(25) TABLE-US-00005 TABLE 5 polymer (P5-1) (P5-2) M.sub.w (g/mol) 2,400 2,280 IP 1.82 1.76 decarboxylation rate (%) 20 32 suspension (S5-1) (S5-2) d.sub.50 (μm) 1.58 1.57 viscosity (mPa .Math. s) 1,400 544 |Mütek charge| (μeq/g) 2.6 2.5

(26) It is further observed that the grinding aid agents according to the invention make it possible to produce suspensions of low viscosity mineral filler particles the median diameter of which is 1.5±0.15 μm. The cationic demand of these suspensions is less than or equal in absolute value to 5μ-equivalent per gram of suspension of particles in water at a concentration of 65% by weight.

(27) All of these examples indicate that the different grinding aid agents according to the invention make it possible to obtain good efficiency during operations of grinding coarse grains of mineral particles. They make it possible to produce suspensions of mineral material particles with well controlled particle size and concentration. These suspensions can then be perfectly pumped and conveyed in the facilities used later, especially during the production of paper-mass composition.

(28) In addition, when these suspensions are used for the production of mass composition of paper mass, their low absolute values of the Mütek charge reduces the quantities of cationic compounds used in these compositions.