Fibers and Nonwovens with Improved Bonding Properties
The present invention relates to fibers, in particular to as-spun fibers, having an improved bonding performance. In particular, the present invention relates to as-spun fibers comprising a metallocene random copolymer of propylene and one or more comonomers. The present invention further relates to nonwovens comprising such fibers and to a process for producing such fibers and nonwovens. The fibers and nonwovens of the present invention are characterized by a wider bonding window as the prior art fibers and nonwovens.
1 - 15 . (canceled)
16 . Fibers comprising a metallocene random copolymer of propylene and one or more comonomers, said comonomers being alpha-olefins different from propylene, wherein the metallocene random copolymer has a comonomer content of from 0.1 wt. % to 1.0 wt. % relative to the total weight of the polymer.
17 . The fibers of claim 16 , wherein the metallocene random copolymer has a melting temperature of at least 140° C.
18 . The fibers of claim 16 , wherein the fibers are as-spun fibers.
19 . The fibers of claim 16 , wherein the metallocene random copolymer has a comonomer content of from 0.2 wt. % to 0.8 wt. %.
20 . The fibers of claim 16 , wherein the metallocene random copolymer is a random copolymer of propylene and ethylene.
21 . Nonwoven comprising the fibers of claim 16 .
22 . The nonwoven of claim 21 , wherein the nonwoven is a spunbond nonwoven.
23 . A laminate comprising the nonwoven of 21 .
24 . A process for the production of a spunbond nonwoven comprising:
(a) providing a blend comprising a metallocene polypropylene;
(b) feeding the blend of step (a) to an extruder;
(c) subsequently melt-extruding the blend to obtain a molten polymer stream;
(d) extruding the molten polymer stream of step (c) from a number of fine, usually circular, capillaries of a spinneret, thus obtaining filaments of molten polymer; and
(e) subsequently rapidly reducing the diameter of the filaments obtained in the previous step to a final diameter, wherein the metallocene polypropylene is a metallocene random copolymer of propylene and one or more comonomers, said comonomers being alpha-olefins different from propylene, wherein the metallocene random copolymer has a comonomer content of from 0.1 wt. % to 1.0 wt. % relative to the total weight of the polymer.
25 . A process for the production of multicomponent fibers and filaments comprising:
(a1) providing a first blend comprising a metallocene polypropylene;
(a2) providing at least one further blend comprising, a thermoplastic polymer;
(b1) feeding each of the blends of steps (a1) and (a2) to a separate extruder;
(c1) consecutively melt-extruding the blends to obtain a molten polymer stream for each blend;
(d1) co-extruding the molten polymer streams of step (c1) from a number of fine capillaries of a spinneret, thus obtaining multicomponent filaments of molten polymer; and
(e) subsequently rapidly reducing the diameter of the filaments obtained in the previous step to a final diameter, wherein the metallocene polypropylene is a metallocene random copolymer of propylene and one or more comonomers, said comonomers bein alpha-olefins different from propylene, wherein the metallocene random copolymer has a comonomer content of from 0.1 wt. % to 1.0 wt. % relative to, the total weight of the polymer.
26 . The process of claim 24 , wherein the melt-extruding is done at a melt temperature in the range from 230° C. to 260° C.
27 . The process of claim 24 , further comprising:
(f) collecting the filaments obtained in step (e) on a support; and
(g) subsequently bonding the collected filaments to form a bonded nonwoven.
28 . The process of claim 24 , further comprising:
(h) laminating a film to the bonded nonwoven obtained in step (g).
29 . The process of claim 24 , wherein the bonded nonwoven is a spunbond nonwoven.
30 . The process of claim 24 , wherein the fibers and filaments are not subjected to a further drawing step.