Bimolecular inverse emulsion polymer
The invention relates to novel, stable bi-molecular cationic inverse emulsion polymers (W/O) with both different molecular weights and cationic activities that are assembled via an “in situ” emulsion polymerization of a high molecular weight cationic polymer in the presence of a low molecular weight polymer in the aqueous phase. The low molecular cationic polymer is produced in a pre-polymerization in solution. The novel, stable cationic water-in-oil emulsion is easy invertible and useful as flocculant, dewatering aid and retention aid in papermaking.
1. A process for preparing a water-in-oil polymer dispersion, comprising radically polymerizing a radically polymerizable cationic monomer, and optionally one or more radically polymerizable, ethylenically unsaturated co-monomers, in a water-in-oil monomer dispersion comprising:
water;
an oily substance;
a water-in-oil emulsifier;
a first cationic polymer obtained from a monomer mixture comprising a cationic (alk)acrylic acid monomer and a radically polymerizable ethylenically unsaturated non-ionic monomer, wherein a content of cationic monomers is at most 95 wt.-%, based on a total weight of monomers;
the radically polymerizable cationic monomer, wherein the radical polymerization of the cationic monomer takes place in the presence of the first cationic polymer; and
optionally, a radically polymerizable, ethylenically unsaturated co-monomer,
wherein the radical polymerization polymerizes the radically polymerizable cationic monomer to form a second cationic polymer; and
wherein the water-in-oil dispersion comprises water, the oily substance, the emulsifier and the first and second cationic polymers.
2. The process of claim 1 , wherein the cationic (alk)acrylic acid monomer is at least one (alk)acryloyloxyalkyl trialkyl ammonium halide.
3. The process of claim 1 , wherein the non-ionic monomer is at least one selected from the group consisting of (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-methyl-N-ethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N,N-diisopropyl acrylamide, vinylformamide, vinyl acetate and styrene.
4. The process of claim 1 , wherein the oily substance is an aliphatic hydrocarbon.
5. The process of claim 1 , wherein the radically polymerizable cationic monomer is an (alk)acrylic acid derivative.
6. The process of claim 5 , wherein the (alk)acrylic acid derivative is selected from the group consisting of a (alk)acrylamidoalkyltrialkyl ammonium halide, a (alk)acryloyloxyalkyl trialkyl ammonium halide, a alkenyl trialkyl ammonium halide and a dialkenyl dialkyl ammonium halide.
7. The process of claim 1 , wherein the process comprises radically polymerizing a radically polymerizable cationic monomer and one or more radically polymerizable, ethylenically unsaturated co-monomers, and the one or more ethylenically unsaturated co-monomers comprise (alk)acrylamide.
8. The process of claim 1 , wherein a content of the radically polymerizable cationic monomer is within the range of from 0.1 to 50 mol.-%, based on a total amount of the radically polymerizable cationic monomer and the optionally one or more radically polymerizable, ethylenically unsaturated co-monomers.
9. The process of claim 1 , wherein at least one condition is satisfied, selected from the group consisting of: the oily substance is an aliphatic hydrocarbon comprising 6 to 30 carbon atoms; the first cationic polymer is obtained from one or more monomers comprising an (alk)acrylamidoalkyltrialkyl ammonium halide; the radically polymerizable cationic monomer is an (alk)acryloyloxyalkyl trialkyl ammonium halide; and
the radically polymerizable, ethylenically unsaturated co-monomer comprises acrylamide.
10. A water-in-oil polymer dispersion, comprising water, an oily substance, a water-in-oil emulsifier, a first cationic polymer, and a second cationic polymer, wherein the dispersion is obtained by the process of claim 1 .
11. The dispersion of claim 10 , wherein a weight average molecular weight of the second cationic polymer is higher than a weight average molecular weight of the first cationic polymer.
12. The dispersion of claim 10 , wherein a cationicity of the first cationic polymer, + FCP in wt.-%, a content of the first cationic polymer, C FCP in wt.-%, a cationicity of the second cationic polymer, + SCP in wt.-%, and a content of the second cationic polymer, C SCP in wt.-%, satisfy formula (I):
X
=
+
SCP
·
C
SCP
+
FCP
·
C
FCP
,
where
0.5
≤
X
≤
300.
(
I
)
13. The dispersion of claim 10 , wherein the dispersion comprises:
10 to 90 wt.-% of water;
0.1 to 60 wt.-% of the oily substance;
0.1 to 25 wt.-% of the water-in-oil emulsifier;
0.1 to 30 wt.-percent of the first cationic polymer; and the second cationic polymer obtained from:
0.1 to 30 wt.-% of at least one radically polymerizable cationic monomer; and
1.0 to 90 wt.-% of at least one radically polymerizable ethylenically unsaturated co-monomer and all percentages are based on a total weight of the dispersion.
14. A flocculant, comprising the water-in-oil polymer dispersion of claim 10 .
15. A process comprising adding the water-in-oil polymer dispersion of claim 10 to an aqueous cellulosic suspension.
16. A process for preparing a water-in-oil polymer dispersion, comprising radically polymerizing a radically polymerizable cationic monomer and one or more radically polymerizable, ethylenically unsaturated co-monomers, in a water-in-oil monomer dispersion comprising:
water;
an oily substance;
a water-in-oil emulsifier;
a first cationic polymer obtained from a monomer mixture comprising an (alk)acrylic acid monomer and a non-ionic monomer, wherein a content of cationic monomers is at most 95 wt.-%, based on a total weight of monomers;
the radically polymerizable cationic monomer, wherein the radical polymerization of the cationic monomer takes place in the presence of the first cationic polymer; and
a radically polymerizable, ethylenically unsaturated co-monomer
wherein the radical polymerization forms a second cationic polymer comprising polymerized units of the radically polymerizable cationic monomer and a water-in-oil dispersion comprising water, the oily substance, the water-in-oil emulsifier, the first cationic polymer and the second cationic polymer.