Provided are a flame retardant composition that provides a flame-retardant synthetic resin composition excellent in flame retardance and in longitudinal and lateral balance in terms of mold shrinkage factor, and a flame-retardant synthetic resin composition using the same and a molded body thereof. A flame retardant composition contains 0.005 to 5 parts by mass of component (B) based on 100 parts by mass of component (A), wherein component (A) is phosphoric acid salt-based flame retardant and component (B) is one or more compounds each having a structure represented by the following general formula (1):

##STR00001##

In the formula, R.sup.1 to R.sup.4 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R.sup.5 represents a direct bond or an alkanediyl group having 1 to 4 carbon atoms, M.sup.1 represents any of an alkali metal, an alkali earth metal, zinc, aluminum and a hydrogen atom, n is 1 and m is 0 when M.sup.1 represents an alkali metal or a hydrogen atom, n is 2 and m is 0 when M.sup.1 represents an alkali earth metal or zinc, and n is 1, 2 or 3 and m is an integer represented by 3-n when M.sup.1 represents aluminum.

The present invention aims to provide a method for improving the fluidity of a crystal nucleating agent for polyolefin resins without impairing other properties, and a polyolefin resin composition containing the crystal nucleating agent with improved fluidity and having excellent properties including transparency, and a molded article thereof. Adjustment to specific characteristics can improve the fluidity of a crystal nucleating agent for polyolefin resins, and the use of such a crystal nucleating agent having specific characteristics remarkably improves the workability during molding processing and provides a polyolefin resin composition excellent in properties such as transparency, and a molded article thereof.

The present invention aims to provide a method for improving the fluidity of a crystal nucleating agent for polyolefin resins without impairing other properties, and a polyolefin resin composition containing the crystal nucleating agent with improved fluidity and having excellent properties including transparency, and a molded article thereof. Adjustment to specific characteristics can improve the fluidity of a crystal nucleating agent for polyolefin resins, and the use of such a crystal nucleating agent having specific characteristics remarkably improves the workability during molding processing and provides a polyolefin resin composition excellent in properties such as transparency, and a molded article thereof.

A method for producing a resin composition of the present invention is a method for producing a resin composition, the method including a step of obtaining a resin composition by heating and melt-kneading a mixture containing a particulate nucleating agent in which D.sub.50 is equal to or more than 0.1 μm and equal to or less than 300 μm and a thermoplastic resin using a twin screw extruder (100) including, inside a cylinder (10), a screw (50) having kneading discs (60), in which the step of obtaining a resin composition includes an extrusion step of extruding the mixture supplied into the twin screw extruder (100) in an ejection direction under kneading conditions in which X and Y satisfy 4.0≤X in a range of 6.0×10.sup.3≤Y≤7.0×10.sup.4 when a volume-based ejection amount is denoted by X (10.sup.−6.Math.kg.Math.h.sup.−1.Math.mm.sup.−3), and a strain rate is denoted by Y (min.sup.−1).

A method for producing a resin composition of the present invention is a method for producing a resin composition, the method including a step of obtaining a resin composition by heating and melt-kneading a mixture containing a particulate nucleating agent in which D.sub.50 is equal to or more than 0.1 μm and equal to or less than 300 μm and a thermoplastic resin using a twin screw extruder (100) including, inside a cylinder (10), a screw (50) having kneading discs (60), in which the step of obtaining a resin composition includes an extrusion step of extruding the mixture supplied into the twin screw extruder (100) in an ejection direction under kneading conditions in which X and Y satisfy 4.0≤X in a range of 6.0×10.sup.3≤Y≤7.0×10.sup.4 when a volume-based ejection amount is denoted by X (10.sup.−6.Math.kg.Math.h.sup.−1.Math.mm.sup.−3), and a strain rate is denoted by Y (min.sup.−1).

A method for producing a resin composition of the present invention is a method for producing a resin composition, the method including a step of obtaining a resin composition by heating and melt-kneading a mixture containing a particulate nucleating agent in which D.sub.50 is equal to or more than 0.1 μm and equal to or less than 300 μm and a thermoplastic resin using a twin screw extruder (100) including, inside a cylinder (10), a screw (50) having kneading discs (60), in which the step of obtaining a resin composition includes an extrusion step of extruding the mixture supplied into the twin screw extruder (100) in an ejection direction under kneading conditions in which X and Y satisfy 4.0≤X in a range of 6.0×10.sup.3≤Y≤7.0×10.sup.4 when a volume-based ejection amount is denoted by X (10.sup.−6.Math.kg.Math.h.sup.−1.Math.mm.sup.−3), and a strain rate is denoted by Y (min.sup.−1).

Provided are: a nucleating agent capable of imparting excellent mechanical properties to a molded article; a resin composition; a method of producing a resin composition; and a molded article. The nucleating agent contains: (A) an aromatic phosphate metal salt having a structure represented by Formula (1) (wherein, R.sup.1 to R.sup.5 each independently represent a hydrogen atom or an alkyl group; n represents 1 or 2; when n is 1, M.sup.1 represents an alkali metal or dihydroxyaluminum; and when n is 2, M.sup.1 represents an alkaline earth metal, zinc, or hydroxyaluminum); and (B) a carboxylic acid metal salt having a structure represented by Formula (2) (wherein, M.sup.2 represents an alkali metal, an alkaline earth metal, hydroxyaluminum, or dihydroxyaluminum; a represents 1 or 2; x represents 1 or 2; a and x satisfy ax=2; and Z represents a group having a structure represented by Formula (3) or (4)).

##STR00001## ##STR00002##

Provided are: a nucleating agent capable of imparting excellent mechanical properties to a molded article; a resin composition; a method of producing a resin composition; and a molded article. The nucleating agent contains: (A) an aromatic phosphate metal salt having a structure represented by Formula (1) (wherein, R.sup.1 to R.sup.5 each independently represent a hydrogen atom or an alkyl group; n represents 1 or 2; when n is 1, M.sup.1 represents an alkali metal or dihydroxyaluminum; and when n is 2, M.sup.1 represents an alkaline earth metal, zinc, or hydroxyaluminum); and (B) a carboxylic acid metal salt having a structure represented by Formula (2) (wherein, M.sup.2 represents an alkali metal, an alkaline earth metal, hydroxyaluminum, or dihydroxyaluminum; a represents 1 or 2; x represents 1 or 2; a and x satisfy ax=2; and Z represents a group having a structure represented by Formula (3) or (4)).

##STR00001## ##STR00002##

Polyolefin compositions comprising i) a polyolefin, ii) one or more phosphorus—containing benzofuranone compounds and iii) one or more hindered amine light stabilizers are provided excellent protection against discoloration and enhanced thermal stability during melt processing as exhibited by improved retention of molecular weight and maintenance of polymer molecular architecture.

Polyolefin compositions comprising i) a polyolefin, ii) one or more phosphorus—containing benzofuranone compounds and iii) one or more hindered amine light stabilizers are provided excellent protection against discoloration and enhanced thermal stability during melt processing as exhibited by improved retention of molecular weight and maintenance of polymer molecular architecture.