Nonwoven fabric and process for forming the same

Abstract

The present invention relates to an elastic nonwoven fabric comprising a nonwoven web that is made of a plurality of fibers, which fibers are bicomponent fibers which each comprise a first component and a second component, wherein the first component is present in an amount in the range of from 80-95% by weight and the second component is present in an amount in the range of from 5-20% by weight, both weights based on the total weight of each fiber; wherein the first component comprises an ethylene/α-olefin copolymer and the second component comprises a low density polyethylene having a density in the range of from 0.90-0.95 g/cm.sup.3 (as determined with ASTM D792); wherein the first component and the second component both have a melt flow rate in the range of from 10-40 g/10 min (as determined by ASTM D1238 (190° C., 2.16 kg)); and wherein the nonwoven web comprises a side which is provided with a pattern of individualized bonded areas, wherein the surface of the bonded areas is in the range of 8-25%, based on the total surface of the side. The present invention further relates to a process for preparing the nonwoven fabric, and an article comprising the nonwoven fabric.

Claims

1. An elastic nonwoven fabric comprising a nonwoven web that is made of a plurality of fibers, which fibers are bicomponent fibers which each comprise a first component and a second component, wherein the first component is present in an amount in the range of from 80-95% by weight and the second component is present in an amount in the range of from 5-20% by weight, both weights based on the total weight of each fiber; wherein the first component comprises an ethylene/α-olefin copolymer and the second component comprises a low density polyethylene having a density in the range of from 0.93-0.95 g/cm.sup.3 (as determined with ASTM D792); wherein in the ethylene/α-olefin copolymer the amount of α-olefin present is in the range of from 2-70 mole %, based on the total copolymer; wherein the bicomponent fibers have a core-sheath structure in which the core part comprises the first component and the sheath part comprises the second component; wherein the first component and the second component both have a melt flow rate in the range of from 10-40 g/10 min (as determined with ASTM D1238 (190° C., 2.16 kg)); and wherein the nonwoven web comprises a side which is provided with a pattern of individualized bonded areas, wherein the surface of the bonded areas is in the range of 8-25%, based on the total surface of the side.

2. The nonwoven fabric according to claim 1, wherein the first component comprises an ethylene/α-olefin block copolymer.

3. The nonwoven fabric according to claim 1, wherein both the first component and the second component have a melt flow rate in the range of from 10-30 g/10 min (as determined with ASTM D1238 (190° C., 2.16 kg)).

4. The nonwoven fabric according to claim 1, wherein both the first component and the second component have a melt flow rate in the range of from 10-25 g/10 min (as determined with ASTM D1238 (190° C., 2.16 kg)).

5. The nonwoven fabric according to claim 1, wherein the surface of the bonded areas is in the range of from 8-20%, based on the total surface of the side.

6. The nonwoven fabric according to claim 1, wherein the surface of the bonded areas is in the range of from 8-15%, based on the total surface of the side.

7. The nonwoven fabric according to claim 1, wherein the nonwoven web has a basis weight in the range of from 5-50 g/m.sup.2.

8. The nonwoven fabric according to claim 1, wherein the first component is present in an amount in the range of from 83-93% by weight and the second component is present in an amount in the range of from 7-17% by weight, based on the total weight of each fiber.

9. The nonwoven fabric according to claim 1 wherein the ethylene/α-olefin copolymer is a single-site catalyzed copolymer.

10. The nonwoven fabric according to claim 1, wherein the bonded areas have a circle, diamond, rectangle, square, oval, triangle, rod, heart, moon star, hexagonal, octagonal or another polygon shape.

11. A process for preparing an elastic nonwoven fabric comprising the steps of (a) providing a first stream of a molten or semi-molten ethylene/α-olefin copolymer; (b) providing a second stream of a molten or semi-molten low density polyethylene having a density in the range of from 0.93-0.95 g/cm.sup.3 (as determined with ASTM D792), wherein both the ethylene/α-olefin copolymer and the polyethylene have a melt flow rate in the range of from 10-40 g/10 min (as determined with ASTM D1238 (190° C., 2.16 kg)); (c) forming from the first stream and the second stream a plurality of bicomponent fibers which each comprise a first component comprising the ethylene/α-olefin copolymer and a second component comprising the polyethylene, wherein the first component is present in an amount in the range of from 80-95% by weight and the second component is present in an amount in the range of from 5-20% by weight, both weights based on the total weight of each fiber, and wherein the bicomponent fibers have a core-sheath structure in which the cored part comprises the first component and the sheath part comprises the second component; (d) forming from the bicomponent fibers as obtained in step (c) a nonwoven web; and (e) feeding the nonwoven web formed in step (d) into a nip defined between oppositely positioned first and second rolls, whereby at least one of the rolls has a patterned outside surface to apply a pattern of individualized bonded areas to the nonwoven web, wherein the nonwoven web comprises a side which is provided with the pattern of individualized bonded areas, wherein the surface of the bonded areas is in the range of 8-25% based on the total surface of the side.

12. An article comprising the nonwoven fabric according to claim 1.

13. The absorbent article according to claim 12, wherein the article is an infection control product or a personal care product.

Description

(1) In FIG. 1, a side of a non-woven fabric is shown having a bond pattern which comprises a first and second pattern in accordance with the present invention. The first pattern of individualized bonded areas 1 defines a second pattern of non-bonded areas 2. The individualized bonded areas 1 are in the form of circles and the non-bonded areas 2 have a hexagonal type of shape.

(2) In FIG. 2, a side of a nonwoven fabric is shown having an alternating pattern of individualized bonded areas in the form of ovals.

(3) In FIG. 3, a side of a nonwoven fabric is shown having an alternating pattern of individualized bonded areas in the form of rods in the cross direction of the web which define a non-bonded area.

(4) In FIG. 4, a nonwoven fabric is shown having a pattern of individualized bonded areas in the diamonds.

EXAMPLES

(5) In Examples 1 and 2 use has been made of a a Reicofil 3 spunbond pilot line of 1 meter width with a bico core/sheath set-up to manufacture bicomponent fibers having a core/sheath configuration. The line was equipped with an extruder A for the first component (core) and an extruder B for the second component (sheath). Both components were fed to the extruder via hoppers in the corresponding core/sheath ratio, heated to 230° C. and forwarded to the spin pack as two separate streams. The total line throughput was 170 kg/h/m.

(6) The spin pack used was equipped with Hills core/sheath bico plates, consisted of round spinning nozzles having a diameter of 0.6 mm, and 5000 holes per linear meter. The two combined melt streams which formed a core/sheath fibers left the nozzles to enter a quench chamber. The fibers were concomitantly quenched and drawn to fine filaments (quench air temperature is 20° C.), the resulting filaments were collected on a conveyor belt and transported to a calender comprising an upper calender roll carrying a bond pattern and a lower calender roll with a smooth surface to consolidate the filaments via pressure and heat.

(7) In Table 1, a comparison is made between a fabric according to the invention (Example 1) and a fabric which is not in accordance with the invention (Example 2 which is an comparative example).

(8) TABLE-US-00001 TABLE 1 Fabric characteristics and properties Example 1 Example 2 Filament Core/ 80/20 80/20 Sheath Rati Core polymer Infuse 9817 (Dow): Versify 4200 (Dow): metallocene-catalyzed random propylene- ethylene-1-octene ethylene copolymer block copolymer (density: 0.876 g/cm3 (density: 0.879 g/cm3 (ASTM D792); and (ASTM D792); and Melt flow rate: Melt flow rate: 15 g/ 8 g/10 min 10 min (ASTM D1238)) (ASTM D1238)) Sheath polymer Aspun 6000 (Dow): low Aspun 6850 (Dow): high densiity polyethylene density polyethylene (density: 0.935 g/cm3 (density: 0.955 (ASTM D792); (ASTM D792); and Melt flow rate: and Melt flow 19 g/10 min rate 30 g/10 min (ASTM D1238)) (ASTM D1238)) Basis weight (gsm) 33 gsm 30 gsm Bonding pattern hexadot bonding area: hexadot bonding area: 11% 11% Elongation in CD 260% 184% F @ 10% elongation 1.15 N/5 cm 7.05 N/5 cm permanent set 13% 29%

(9) Elongation in CD and tensile strength at 10% elongation was determined according DIN 53857 at a Zwick tensile tester, whereas the permanent set was determined via a hysteresis test according DIN 53835 at a Zwick tensile tester. From Table 1 it will be clear that the fabric in accordance with the present invention (Example 1) displays much more attractive elongation and resilience properties when compared with the fabric which falls outside the scope of the present invention (Example 2).