Abstract: A process for preparing particulate water-soluble cationic acrylic polymers having a high molecular weight, an excellent water solubility and a uniform particle size with a good productivity by adding a combined photoinitiator system of an azoguanyl compound and other usual photoinitiator to an aqueous monomer solution containing a cationic vinyl monomer, irradiating the aqueous monomer solution in the form of a thin layer on a moving support with ultraviolet rays in at least two stages, and finely dividing the produced aqueous polymer gel in a wet state by a roller cutter and then by a vertical cutter.

Abstract: A novel process for preparing particles of polymer gel prepared by polymerizing an aqueous solution of water-soluble vinyl monomers which comprises breaking the polymer gel into particles with a breaker device wherein the gel is cut into strips by a pair of rollers having a plurality of annular projections or grooves on their surfaces, the rollers rotating in an opposite direction to each other to engage each other and cut off the gel fed between the rollers, and the strips are then cut into particles by a combination of a fixed cutting blade and a rotating cutting blade. The obtained gel particles are further pulverized into fine round or particles spherical in a vertical type cutter comprising at least one vertically fixed cutting blade and a rotary cutting blade arranged rotatably and vertically, a clearance being provided between an edge of the rotary cutting blade and an edge of the fixed blade.

Abstract: An improved process for preparing a water-soluble polymer having an excellent water solubility and a high molecular weight, which comprises subjecting a thin layer of an aqueous solution of a water-soluble vinyl monomer to polymerization on a solid support, covering the thin layer with a substantially water-insoluble organic material, e.g. a paraffin, a silicone oil or a low molecular polyethylene, and/or a slightly water-soluble or substantially water-insoluble alkylene oxide adduct at least at a point of time when the aqueous monomer solution has not freely flowed, and further continuing the polymerization.

Abstract: A process for preparing particulate water-soluble acrylic polymers, e.g. acrylamide or methacrylamide polymers and cationic acrylic polymers, having a high molecular weight, an excellent water solubility and a uniform particle size with a good productivity, which comprises:(a) adding at least one surfactant selected from the group consisting of a non-ionic surfactant and an anionic surfactant to an at least 20% by weight aqueous solution of a vinyl monomer in an amount of 0.001 to 1% by weight based on the monomer.(b) adjusting the dissolved oxygen in the aqueous monomer solution to at most 1 mg/liter,(c) admixing the aqueous monomer solution with at most 0.

Abstract: An improved process for preparing a sticky water-soluble polymer, e.g. acrylamide polymers and acrylic acid polymers, which comprises polymerizing an aqueous solution of a monomer in a polymerization vessel of which the surface contacting the aqueous monomer solution is covered with a tetrafluoroethylene-ethylene copolymer film, whereby the stickiness of the produced polymer to the vessel is remarkably decreased, namely the peelability of the polymer from the vessel is remarkably improved, and moreover the polymerization conversion is remarkably improved. Also, the use of a metal deposited tetrafluoroethylene-ethylene copolymer film as a covering material improves the efficiency of a photopolymerization and enables to use a polymerization vessel made of an inexpensive material.