Abstract: There is disclosed a process for producing an acrylamide polymer which comprises polymerizing acrylamide monomer alone or a monomer mixture composed of 50 mole % or more of acrylamide monomer and a monomer capable of copolymerizing with acrylamide monomer in the presence of an azo series polymerization initiator and 0.1% by weight or more of 2-mercaptobenzothiazole or a salt thereof based on the weight of the monomer in an aqueous medium having a pH of 6 or higher at a temperature range of 5 to 100.degree. C., and then drying the resulting material.

Abstract: The invention relates to a process for producing a powder of a cationic polymer by spreading on a moveable carrier a layer of an aqueous solution of a vinyl monomer, carrying out continuous polymerization followed by peeling off hydrous polymer from the carrier in a hot state, and cutting said hydrous polymer in a hot state by a shearing stress.

Abstract: Polyacrylamide in the form of aquagel is partially hydrolyzed in such a manner that small pieces of the aquagel are mixed with an alkali agent in a specified quantity and maintained at a temperature of 50.degree. to 95.degree. C. until the hydrolysis reaches substantial completion. The quantity of the alkali agent is that corresponding to 1/1.1 to 1/3 of the hydrolysis percentage desired of the final partially hydrolyzed polyacrylamide. The partially hydrolyzed polyacrylamide thus produced is characterized by uniform hydrolysis evidenced by its improved solubility in water and a pH around 7 of its aqueous solution. The term "aquagel" is herein used interchangeably with a term "hydrogel".

Abstract: A process for preparing a cationic polymer which comprises polymerizing a monomer mixture containing acrylamide and a cationic alkenyl monomer represented by the general formula: ##STR1## wherein R.sup.1 represents H or CH.sub.3 ; R.sup.2 and R.sup.3 represent independently CH.sub.3 or C.sub.2 H.sub.5 ; R.sup.4 represents H, CH.sub.3, C.sub.2 H.sub.5 or a benzyl group; A represents --OC.sub.n H.sub.2n -- (wherein n=2 or 3), ##STR2## or --NC.sub.n H.sub.2n -- (wherein n=2 or 3); and X.sup.- represents Cl.sup.-, Br.sup.-, I.sup.-, CH.sub.3 SO.sub.4.sup.-, C.sub.2 H.sub.5 SO.sub.4.sup.-, 1/2SO.sub.4.sup.-- or CH.sub.3 COO.sup.-, in the form of a sheet in an aqueous medium, characterized in that the composition ratio of acrylamide/cationic alkenyl monomer is within the range of 95/5 to 5/95, and the polymerization is carried out in the presence of a phosphite. The polymers obtained according to this process are free from insolubles produced under the influence of oxygen.

Abstract: Acrylamide polymers having remarkably high molecular weights can be obtained by polymerizing acrylamide or a monomer mixture comprising a preponderant quantity of acrylamide in an aqueous medium with the use of a specific redox initiator and a specific azo compound initiator. The polymerization initiator used in this porcess comprises a combination of a persulfate, formaldehyde sodium sufoxylate and 2,2'-azobis-2-amidinopropane.

Abstract: When an alkaline substance is added to and mixed with aggregates of the mutually adhering blobs of a hydrogel of an acrylamide polymer, (1) a mixing tank in which the portion to be contacted with the hydrogel of an acrylamide polymer is made of a chromium-plated material is used, and (2) to said hydrogel aggregates is added at least one compound represented by the general formulae: ##STR1## wherein R.sub.1 is a residue obtained by removing two OH groups from a saturated dihydric alcohol having 2 to 4 carbon atoms, and R.sub.2 is a residue obtained by removing three OH groups from a saturated trihydric alcohol having 3 to 6 carbon atoms, and having an average molecular weight of 500 to 5,000, whereby the hydrolysis of the acrylamide polymer can be achieved at a high efficiency while preventing the mutual adhesion of the hydrogel aggregates and also reducing the adhesion of the aggregates to the interior surface of the mixing tank to such an extent that there is substantially no problem of adhesion.

Abstract: In the production of a dried acrylamide polymer by polymerizing, in an aqueous medium, acrylamide alone or a monomer mixture comprising 50 mole % or more of acrylamide and at least one monomer copolymerizable therewith with a radical initiator, and then drying the resulting hydrous acrylamide polymer, the allowing of 2-mercaptobenzimidazole to be present in the drying step or a step prior thereto enables the dried acrylamide polymer having a high molecular weight and a good dissolvability in water to be obtained.

Abstract: A method for producing a water-soluble cationic polymer by polymerizing, in the presence of water, a high concentration of (a) at least one vinyl monomer represented by the following general formula (I)ch.sub.2 .dbd.cr.sub.1 coor.sub.2 n.sup..sym. r.sub.3 r.sub.4 r.sub.5 x.sup..crclbar. (i)wherein R.sub.1 is --H or --CH.sub.3 ; R.sub.2 is --CH.sub.2 CH.sub.2 -- or --CH.sub.2 CH(OH)CH.sub.2 --; R.sub.3 and R.sub.4, which may be the same or different, each is --CH.sub.3 or --CH.sub.2 CH.sub.3 ; R.sub.5 is --C.sub.n H.sub.2n+1 where n is 0 or an integer of 1 to 4, --CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 COOH; and X is Cl.sup.-, Br.sup.-, 1/2SO.sub.4.sup.-- or CH.sub.3 SO.sub.4.sup.