Abstract: A terminal-modified polyamide 4 having improved thermal stability is provided. The terminal-modified polyamide 4 consists of a polyamide 4-derived site (A) and a polyalkylenimine-derived site (B), and has a structure in which a polyalkylenimine is amide-bonded to a polymerization terminal of polyamide 4. The weight ratio between the polyamide 4-derived site (A) and the polyalkylenimine-derived site (B) is 100:0.01-100:20. The polyamide 4-derived site (A) is a site derived from polyamide 4 having a number average molecular weight (Mn) of 1,000 to 2,000,000, and the polyalkylenimine-derived site (B) is a site derived from a polyalkylenimine having a number average molecular weight (Mn) of 400 to 100,000.

Abstract: The present invention aims to provide a new method for producing polyamide 4 particles. The method for producing polyamide 4 particles of the present invention comprises mixing an emulsified liquid (D) obtained by mixing a solution (B) obtained by dissolving polyamide 4 in a good solvent (A) for polyamide 4 and a solvent (C) which is incompatible with the solution (B), and a solvent (E) which is a poor solvent for polyamide 4 and is compatible with the good solvent (A) and the solvent (C). The above emulsified liquid (D) may further comprise a surfactant, and the volume average diameter of the obtained polyamide 4 particles is usually in the range of 10 ?m to 500 ?m.

Abstract: A method for producing a polyamide-4 particle that includes polymerizing 2-pyrrolidone in an aprotic solvent incompatible with 2-pyrrolidone in the presence of a polymerization initiator and a 2-pyrrolidone lithium salt or polymerizing 2-pyrrolidone in an aprotic solvent incompatible with 2-pyrrolidone in the presence of a polymerization initiator, a 2-pyrrolidone lithium salt and a 2-pyrrolidone sodium salt. A volume average particle size of the resulting polyamide-4 particle is 1 ?m to 100 ?m, and a molecular weight distribution (Mw/Mn) of the polyamide-4 particle is 1.0 to 5.0.