Abstract: A method for manufacturing a powdery paper-strengthening agent including a branched (meth)acrylamide-based polymer (A) which includes a step of obtaining (A) component by polymerizing (meth)acrylamide (a1), anionic vinyl monomer (a2), cationic vinyl monomer (a3) and crosslinkable vinyl monomer (a4) in a solvent in a presence of a polymerization initiator, a step of dropping or putting the above (A) component into an organic solvent to form a precipitate, and a step of drying and pulverizing (A) component obtained as the precipitate.

Abstract: A papermaking agent exhibiting an excellent freeness and paper strength effect with little increase in viscosity after long-term storage. A papermaking agent including a (meth)acrylamide polymer containing two or more starches (a1) selected from the group consisting of unmodified starch, oxidized starch, esterified starch, etherified starch, amidated starch, cationic starch, amphoteric starch and crosslinked starch, a (meth)acrylamide (a2), a polymerizable monomer having an amino group (a3), a polymerizable monomer having a carboxy group (a4) and a polymerizable monomer having a sulfonate group (a5) as essential constituent components.

Abstract: A relatively inexpensive papermaking agent having a high concentration and a high molecular weight that exhibits an excellent freeness and paper strength effect obtained using starches which are biomass materials. A papermaking agent which is a (meth)acrylamide polymer containing starches (a1), a (meth)acrylamide (a2), a polymerizable monomer having an amino group (a3), a polymerizable monomer having a carboxy group (a4) and a polymerizable monomer having a sulfonate group (a5) as essential constituent components, wherein the ratio between the amount of the component (a1) used in terms of non-volatile content weight and a total amount of the components (a2) to (a5) used is [(a1)/{(a2)+(a3)+(a4)+(a5)}]=5/95 to 45/55, and wherein the (meth)acrylamide polymer has a non-volatile content concentration of 22 to 35 weight %, and a weight average molecular weight of 1,500,000 to 7,000,000.

Abstract: A method for manufacturing a powdery paper-strengthening agent including a branched (meth)acrylamide-based polymer (A) which includes a step of obtaining (A) component by polymerizing (meth)acrylamide (a1), anionic vinyl monomer (a2), cationic vinyl monomer (a3) and crosslinkable vinyl monomer (a4) in a solvent in a presence of a polymerization initiator, a step of dropping or putting the above (A) component into an organic solvent to form a precipitate, and a step of drying and pulverizing (A) component obtained as the precipitate.

Abstract: A powdery paper-strengthening agent comprising a branched (meth)acrylamide-based polymer (A).