Fiber for artificial hair and hair ornament product including same

A hair ornament product, comprising:

• a thermoplastic fiber having a cross section comprising an outer circumference and a hollow center,
• wherein
• the outer circumference has a shape comprising two overlapping circles or two overlapping ellipses directly connected by recessed portions, wherein the recessed portions have a form of arcs, or each recessed portion has a bottom point formed by the two overlapping circles or ellipses forming acute angles in the recessed portions,
• the hollow center is non-circular or non-elliptical and has a shape of a quadrangle, a hexagon, a combination of a quadrangle and an arc, or a combination of a hexagon and an arc,
• the hollow center is located in the center of the cross section and a ratio of an area of the hollow center to an area of the cross section is from 10% to 40%,
• an average value of a maximum straight line distance and a minimum straight line distance between a first side and a second side of the hollow center is from 50% to 150% relative to an average value of a maximum straight line distance and a minimum straight line distance between a first minor axis and a second minor axis in the cross section,
• the thermoplastic fiber comprises a polyester-based resin composition comprising 100 parts by weight of a polyester resin and from 5 to 40 parts by weight of a brominated epoxy-based flame retardant, and
• the polyester resin is at least one selected from the group consisting of polyalkylene terephthalate and a copolymerized polyester comprising polyalkylene terephthalate.

A method for forming a thermoplastic fiber for artificial hair,

• wherein
• the thermoplastic fiber has a cross section comprising an outer circumference and a hollow center,
• the outer circumference has a shape comprising two overlapping circles or two overlapping ellipses directly connected by recessed portions, wherein the recessed portions have a form of arcs, or each recessed portion has a bottom point formed by the two overlapping circles or ellipses forming acute angles in the recessed portions,
• the hollow center is non-circular or non-elliptical and has a shape of a quadrangle, a hexagon, a combination of a quadrangle and an arc, or a combination of a hexagon and an arc,
• the hollow center is located in the center of the cross section and a ratio of an area of the hollow center to an area of the cross section is from 10% to 40%,
• an average value of a maximum straight line distance and a minimum straight line distance between a first side and a second side of the hollow center is from 50% to 150% relative to an average value of a maximum straight line distance and a minimum straight line distance between a first minor axis and a second minor axis in the cross section,
• the thermoplastic fiber comprises a polyester-based resin composition comprising 100 parts by weight of a polyester resin and from 5 to 40 parts by weight of a brominated epoxy-based flame retardant, and
• the polyester resin is at least one selected from the group consisting of polyalkylene terephthalate and a copolymerized polyester comprising polyalkylene terephthalate;
• the method comprising:
• dry blending a resin composition to form a polymer mixture;
• extruding the mixture to form polymer pellets;
• drying the polymer pellets;
• melting the dried polymer pellets in a melt spinning machine;
• and
• extruding the melted polymer pellets through a spinneret to obtain the thermoplastic fibers,
• wherein the spinneret comprises a cocoon-shaped or spectacle-shaped nozzle and a quadrangle-shaped nozzle hole.