Abstract: An aqueous dispersion of a copolymer comprising:(A) from 20 to 90 percent by weight of an unsaturated carboxylic acid of the formula ##STR1## where R.sub.1, R.sub.2, R.sub.3 are hydrogen, alkyl, or --(CH.sub.2).sub.n COOM and M is a proton or an alkali metal or alkaline earth metal or an ammonium cation, and(B) from 10 to 80 percent of at least one other comonomer different from and copolymerizable with A; methods of making a ready-to-use foundry molding sand by mixing such a dispersion with sand; and such ready-to-use foundry molding sands.

Abstract: A method for making an aqueous polymodal synthetic resin dispersion by the emulsion polymerization of an ethylenically unsaturated monomer difficultly soluble in water, or a mixture of such monomers forming a polymer which is water insoluble under the conditions of polymerization, in an aqueous phase containing an emulsifier and a water soluble polymerization initiator, which method comprises adding a seed latex to the polymerization mixture in the course of the emulsion polymerization before more than 40 weight percent of said monomers have been polymerized, the particles of said seed latex being smaller by a factor ranging from 2 to 15 than are particles already formed by emulsion polymerization, the amount by weight of the particles in the seed latex being not greater than 10 percent by weight of the monomers and the ratio by weight of particles of said seed latex to the weight of the monomers already polymerized being from 1:4 to 1:500.

Abstract: What is disclosed is making highly concentrated, bimodal, aqueous synthetic resin dispersions by the emulsion polymerization of ethylenically unsaturated monomers, in the presence of emulsifiers and free radical-forming initiators, by adding to a first latex containing a first dispersed synthetic resin and an aqueous phase, a second latex containing a second dispersed synthetic resin and an aqueous phase and a monomer phase containing a free-radically polymerizable monomer, and then polymerizing the monomer, the average size of the particles of said first resin differing by a factor between 2 and 15 from that of the particles of second resin, the total weight of the resins and monomers representing 100 parts by weight, and the total weight of the aqueous phases representing not more than 70 parts by weight.