Extrusion apparatus for turf fiber monofilament

1 . An extrusion apparatus suitable for manufacturing artificial turf polymer fiber free of fiber splitting, the extrusion apparatus comprising an extrusion head comprising:

an inlet for receiving a polymer material,

a nozzle, and

a nozzle outlet,

wherein the nozzle is in hydraulic connection with the inlet and the nozzle outlet, and

wherein a ratio of an equivalent diameter of the nozzle outlet over an axial length of an inner capillary channel of the nozzle is from 0.90 to 1.10,

wherein the equivalent diameter is the diameter of a circle-shape cross-section nozzle outlet having a same area as an area of an actual cross-section of the nozzle outlet.

2 . The extrusion apparatus of claim 1 , wherein the nozzle outlet has a circle-shape cross-section, an oval-shape cross-section, a rectangular shape cross-section, a V-shape cross-section, a W-shape cross-section, a C-shape cross-section, an Q-shape cross-section, or any combination thereof.

3 . The extrusion apparatus of claim 1 , wherein the equivalent diameter of the nozzle outlet from 0.25 mm to 5 mm.

4 . The extrusion apparatus of claim 1 , wherein the polymer fiber is made of LLDPE including LLDPE-C4.

5 . The extrusion apparatus of claim 1 , wherein the axial length of the inner capillary channel of the nozzle is from 0.5 mm to 5.0 mm.

6 . The extrusion apparatus of claim 1 , wherein the nozzle outlet comprises a rectangular-shape cross-section having a width to thickness ratio (WTR) from 2 to 30.

7 . The extrusion apparatus of claim 1 , wherein the nozzle outlet comprises a circle-shape cross section, an oval-shape cross section or a rectangular-shape cross section, or any combination thereof.

8 . The extrusion apparatus of claim 1 , wherein the nozzle outlet has a central opening having a concave-shape, rectangular-shape, or circle-shape cross section and first and second edge openings having a circle-shape, oval-shape, or rectangular shape cross section arranged symmetrically with respect to a longitudinal axis of symmetry of the capillary channel of the nozzle.

9 . The extrusion apparatus of claim 8 ,

wherein the central opening of the nozzle outlet has a constant thickness along its entire width, and

wherein the first and second edge openings of the nozzle outlet each has a circle-shape cross section.

10 . The extrusion apparatus of claim 9 ,

wherein the central opening has a radius curvature of 1.2 mm to 2.0 mm, a width of 2.5 mm to 6.0 mm and a thickness of 0.3 mm to 0.7 mm, and

wherein the first and second edge openings each have a radius of from 0.3 mm to 0.7 mm.

11 . The extrusion apparatus of claim 1 , further comprising a heating element for heating the polymer to have at the nozzle outlet a temperature of 225° C. to 260° C.

12 . Use of the extrusion apparatus of claim 1 in a method for making artificial turf fiber,

wherein LLDPE polymer material comprising LLDPE-C8, or LLDPE-C6, or LLDPE-C4 or a combination thereof is fed through the extrusion head and processed through the extrusion head to produce artificial turf fiber substantially free of splitting.

13 . The use of the extrusion apparatus as in claim 12 ,

wherein the extruded polymer mass at the nozzle outlet has a viscosity as measured by a melt flow index of 0.2 to 15 g/10 min, a temperature of 190° C. to 250° C., and a density of 0.86 to 0.98 g/cm3,

wherein the pressure at the extrusion is 30 to 120 bar, and

wherein the polymer mass is extruded at a speed of 100 to 600 m/min.

14 . A method for making turf fiber from LLDPE-C4 that is resistant to splitting, the method comprising:

feeding LLDPE to an extrusion apparatus,

heating the LLDPE to a temperature above its melting point and extruding the melted LLDPE through the nozzle outlet to form a turf fiber,

wherein the extrusion apparatus is according to claim 1 .

15 . The method of claim 14 ,

wherein the extruded polymer mass at the nozzle outlet has a viscosity as measured by a melt flow index of 0.2 to 15, a temperature of 190° C. to 250° C., and a density of 0.86 to 0.98 g/cm3,

wherein the pressure at the extrusion is 30 to 120 bar, and

wherein the polymer mass is extruded at a speed of 100 to 600 m/min.