Water-absorbent surface-modified-clay linked polymers

A method for making a water-absorbing surface-modified-clay linked polycarboxylic acid and/or polycarboxylate polymer, comprising the steps of:

• a) obtaining an aqueous polymerization reaction liquid comprising i) homogeneously dispersed therein, clay platelets with opposing basal platelet surfaces and platelet edges;
• and ii) dissolved or homogeneously dispersed therein, polymerizable monomers comprising a carboxylic acid group and/or carboxylate group, and/or polymerizable oligomers of one or more of the monomers;
• wherein the aqueous liquid has a pH of about 6 or less;
• wherein at least about 20%, by weight, of the monomers and/or oligomers are neutralized;
• and wherein the basal surface(s) of the clay platelets are modified with one or more surface modification compound(s);
• b) obtaining a polymerization initiator system;
• c) combining the liquid of a) with the polymerization initiator system of b) and polymerizing the monomers and/or oligomers;
• wherein the water-absorbing surface-modified clay linked polymer exhibits a Centrifuge Retention Capacity (CRC) in a 0.9% saline solution in demineralized water, of at least about 10 g of saline per gram of polymer.

A method for making an aqueous polymerization reaction liquid suitable for making water-absorbing surface-modified-clay linked polyacrylate/poly acrylic acid polymers, the method comprising the steps of:

• a) obtaining a first aqueous mixture, being an aqueous solution or dispersion of the acrylic acid and/or acrylate salt monomers, or oligomers thereof, wherein at least about 20%, by weight, of the monomers or oligomers are neutralized;
• b) obtaining a clay or clay dispersion;
• and
• c) obtaining one or more surface modification compound(s) having a cationic moiety that can bind to a clay platelet's basal plate, or a dispersion or solution thereof,
• d) (i) combining the solution or dispersion of (a) and the clay or clay dispersion of (b) first, and then combining this mixture with the surface modification compound or dispersion or solution of (c);
• or
• (ii) combining the solution or dispersion of (a) and the clay or clay dispersion of (b) and the surface modification compound or dispersion or solution of (c) simultaneously;
• or
• (iii) combining the clay or clay dispersion of (b) and the surface modification compound or dispersion or solution of (c) first, and then combining this with the solution or dispersion of (a);
• and
• e) ultrasonic or shear force mixing at least in step d)(i), d)(ii), or d(iii);
• to obtain the aqueous polymerization reaction liquid, which has a pH of about 6 or less, which comprises the polymerizable monomers, polymerizable oligomers and/or mixtures thereof, and which has homogeneously dispersed therein clay platelets with modified basal surfaces;
• wherein the water-absorbing surface-modified clay linked polymer exhibits a Centrifuge Retention Capacity (CRC) in a 0.9% saline solution in demineralized water, of at least about 10 g of saline per gram of polymer.