EP4577690A1 - Bicomponent fiber - Google Patents

Abstract

The invention relates to a bicomponent fiber having a core-sheath configuration, wherein the core comprises a polypropylene composition and the sheath comprises a first polyethylene composition and a second polyethylene composition, wherein the first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min and comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE) and the second polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min.

Description

Classification: General Business Use 22POLY0027-WO-PCT 1 BICOMPONENT FIBER The present invention relates to a bicomponent fiber, a process for making such bicomponent fiber, a non-woven fabric comprising such bicomponent fiber, a process 5 for making such non-woven fabric and an article comprising such non-woven fabric. Polyolefin, as a well-known thermal plastic, has been widely used in both fibers of clothing, filtration and especially nonwoven fabrics of hygienic and medical fields, e.g., diapers, incontinence pads, sanitary wipes and surgical gowns and drapes. Compared 10 to mono-component systems (100% polypropylene(PP)-based polymers), the development of bicomponent fibers/nonwovens, e.g., PP, polyester(PET) and/or polyamides(PA) combined with polyethylene(PE), has led to an increasing industry and customer demand, because such combinations can provide sufficient mechanical properties as well as other desired physical characteristics. During the bicomponent 15 fiber processing, molten polymers (for example PE and PP) meet each other at the outlets of spinnerets with a designed configuration, e.g., sheath-core configuration. WO2011115702 discloses a bicomponent fiber comprising a core comprising a first component comprising polypropylene and a sheath comprising a second component 20 comprising a polyethylene composition, wherein said polyethylene composition has a density in the range of from 0.945 to 0.965 g/cm , a molecular weight distribution (Mw/Mn) in the range of from 1.70 to 3.5, a melt index (I2) in the range of from 0.2 to 150 g/10 minutes, a molecular weight distribution (Mz/Mw) in the range of from less than 2.5, vinyl unsaturation in the range of from less than 0.1 vinyls per one thousand 25 carbon atoms present in the backbone of said composition. EP1942213 discloses a fiber, comprising a first polymer component and a second polymer component, wherein the first and second polymer components differ at least with respect to one property, and wherein the second polymer component comprises ₃₀ ^{an ethylene-α-olefin copolymer having a density of from 0.945 to 0.965 g/cm3} _{and a} MFR2 of from 15 to 45 g/10 min. An important characteristic of a non-woven fabric is the skin-touch feeling such as softness, smoothness and stiffness. Good mechanical properties such as tensile 35 strength and elongation are also important for a non-woven fabric. If is further important that the fibers from which the non-woven fabrics can be made can be produced in a stable manner. Classification: General Business Use 22POLY0027-WO-PCT 2 It is an objective of the present invention to provide a fiber by which the above- mentioned and/or other problems are solved. 5 Accordingly, the invention provides a bicomponent fiber having a core-sheath configuration, wherein the core comprises a polypropylene composition and the sheath comprises a first polyethylene composition and a second polyethylene composition, wherein 10 the first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min and comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE) and the second polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min. 15 The invention further provides a non-woven fabric comprising the fiber according to the invention. Surprisingly, the fiber according to the invention can be made in a stable manner and 20 the non-woven fabric made according to the invention has a good skin-touch feeling as well as good mechanical properties. Bicomponent fiber The bicomponent fiber according to the invention has a core-sheath configuration. 25 Preferably, the weight ratio between the core and the shell in the bicomponent fiber is 85:15 to 40:60, for example 80:20 to 50:50. Core The core of the bicomponent fiber comprises a polypropylene composition. 30 The amount of the polypropylene composition with respect to the core may e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. The polypropylene composition of the core comprises a polypropylene. Polypropylene 35 maybe a propylene homopolymer, a propylene copolymer such as a propylene alpha olefin copolymer, a random copolymer polypropylene. Classification: General Business Use 22POLY0027-WO-PCT 3 The polypropylene and/or the polypropylene composition may have a melt flow index measured according to ISO1133-1:2011 at 230 ⁰C and 2.16 kg of e.g.5.0 to 50 dg/min, for example 15 to 35 dg/min. 5 The polypropylene composition may comprise additives such as nucleating agents and clarifiers, stabilizers, fillers, plasticizers, anti-oxidants, lubricants, antistatics, scratch resistance agents, impact modifiers, acid scavengers, recycling additives, coupling agents, anti-microbials, anti-fogging additives, slip additives, anti-blocking additives, polymer processing aids, flame retardants, colorants and the like. Such additives are 10 well known in the art. Preferred additives include Irganox 1010, Irganox 168, Irganox 3114 and vitamin E. The amount of the additives may e.g. be 0-5 wt%. The amount of polypropylene with respect to the polypropylene composition may e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. 15 Preferably, the total amount of polypropylene and the additives is 100 wt% with respect to the polypropylene composition. Sheath The sheath of the bicomponent fiber comprises a first polyethylene composition and a 20 second polyethylene composition. The total amount of the first polyethylene composition and the second polyethylene composition with respect to the sheath may e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. 25 Preferably, the weight ratio between the first polyethylene composition and the second polyethylene composition is 95:5 to 60:40, more preferably 90:10 to 70:30, even more preferably 85:15 to 75:25. This results in particularly good properties of the non-woven fabric according to the invention while ensuring that the fiber according to the invention 30 has a high processibility. The first polyethylene composition and/or the second polyethylene composition may comprise additives. Examples of suitable additives are those mentioned as additives of the polypropylene composition. The amount of the additives may e.g. be 0-5 wt%. 35 The amount of polyethylene with respect to the first polyethylene composition may e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. Classification: General Business Use 22POLY0027-WO-PCT 4 Preferably, the total amount of polyethylene and the additives is 100 wt% with respect to the first polypropylene composition. The amount of polyethylene with respect to the second polyethylene composition may 5 e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. Preferably, the total amount of polyethylene and the additives is 100 wt% with respect to the second polypropylene composition. First 10 The first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min. The melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg is preferably 7.5 to 10 dg/min. This is advantageous for obtaining non-woven fabrics with good mechanical properties. 15 The first polyethylene composition comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE). In some embodiments, the amount of HDPE with respect to the first polyethylene 20 composition is at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. The use of HDPE in the sheath of the fiber leads to a good abrasion resistance of the non-woven fabrics made from the fibers according to the invention. In some embodiments, the amount of LLDPE with respect to the first polyethylene 25 composition is at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. The use of LLDPE in the sheath of the fiber leads to a lower temperature being required for the bonding of the fibers in making non-woven fabrics. Second polyethylene composition 30 The second polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min, preferably 20 to 30 dg/min. The second polyethylene composition may comprise at least one of linear density polyethylene (LDPE), HDPE and LLDPE. Preferably, second polyethylene composition 35 comprises LDPE. The use of LDPE in combination with HDPE and/or LLDPE of the first polyethylene composition leads to a lower temperature being required for the bonding of the fibers in making non-woven fabrics. Furthermore, the use of LDPE in Classification: General Business Use 22POLY0027-WO-PCT 5 combination with HDPE and/or LLDPE of the first polyethylene composition ensures a good spinnability which ensures that the fiber according to the invention can be made in a stable manner. 5 In some embodiments, the amount of LDPE with respect to the second polyethylene composition is at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.9 wt% or 100 wt%. HDPE, LLDPE, LDPE 10 The production processes of HDPE, LLDPE and LDPE are summarised in Handbook of Polyethylene by Andrew Peacock (2000; Dekker; ISBN 0824795466) at pages 43- 66. HDPE 15 HDPE has a linear structure with little branching. HDPE may be an ethylene homopolymer or may be an ethylene copolymer having as a comonomer e.g. butene or hexene. 20 Preferably, the HDPE has a density measured according to ISO1183 of 941-970 kg/m³, more preferably 950-967 kg/m³, more preferably 960-967 kg/m³. Preferably, the HDPE has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min, more preferably 7.5 to 10 dg/min. 25 Preferably, the HDPE has a molecular weight (Mw) of 80 to 150 kDa. Preferably, the HDPE has a molecular weight distribution (Mw/Mn) of 7 to 30. 30 LLDPE LLDPE has a linear structure with a significant number of short branching. The technologies suitable for the LLDPE manufacture include gas-phase fluidized-bed polymerization, polymerization in solution, polymerization in a polymer melt under very 35 high ethylene pressure, and slurry polymerization. The LLDPE comprises ethylene and a C3-C10 alpha-olefin comonomer (ethylene- Classification: General Business Use 22POLY0027-WO-PCT 6 alpha olefin copolymer). Suitable alpha-olefin comonomers include 1-butene, 1- hexene, 4-methyl pentene and 1-octene. The preferred co monomer is 1-butene. Preferably, the amount of units derived from the comonomer in the copolymer is 1.0 to 5 5.0 wt%. Preferably, the LLDPE has a density measured according to ISO1183 of 910-940 kg/m³, more preferably 920-940 kg/m³, more preferably 925-935 kg/m³. 10 Preferably, the LLDPE has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min, more preferably 7.5 to 10 dg/min. Preferably, the LLDPE has a molecular weight (Mw) of 50 to 100 kDa. 15 Preferably, the LLDPE has a molecular weight distribution (Mw/Mn) of 1.1 to 8.0. LDPE An LDPE has a structure with long chain branching. 20 The LDPE may be produced by use of autoclave high pressure technology and by tubular reactor technology. LDPE may be an ethylene homopolymer or may comprise a comonomer, for example 1-butene or 1-hexene. Preferably, the LDPE has a density measured according to ISO1183 of 910-940 kg/m³, 25 more preferably 913-935 kg/m³, more preferably 915-925 kg/m³. Preferably, the LDPE has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min, preferably 20 to 30 dg/min. 30 Preferably, the LDPE has a molecular weight (Mw) of 50 to 200 kDa. Preferably, the LDPE has a molecular weight distribution (Mw/Mn) of 4 to 30. The bicomponent fiber according to the present invention may be prepared in any 35 desired thickness depending upon the desired end use. Typical thicknesses are known to the skilled person and may e.g. be 0.5 to 100 denier, such as 1 to 50 denier. Classification: General Business Use 22POLY0027-WO-PCT 7 Other aspects The present invention further provides a process for making the bicomponent fiber according to the invention, comprising the steps of: providing a melt of the polypropylene composition and a melt of the first polyethylene 5 composition and the second polyethylene composition and extruding the melt of the polypropylene composition and the melt of the first polyethylene composition and the second polyethylene composition through a spinneret to obtain the bicomponent fiber. 10 The first polyethylene composition and the second polyethylene may be dry blended before they are fed to the extruder and melted therein to obtain the melt of the first polyethylene composition and the second polyethylene composition. Alternatively, each of the first polyethylene composition and the second polyethylene composition may be fed to the extruder separately and melt-mixed together to obtain the melt of the first 15 polyethylene composition and the second polyethylene composition. The present invention further provides a non-woven fabric comprising the fiber according to the invention. The non-woven fabric according to the invention may have a fabric weight of e.g.10 to 25 gsm. 20 The present invention further provides an article comprising the non-woven fabric according to the invention. Preferably, the article is selected from the group consisting of upholstery, apparel, wall covering, carpet, diaper topsheet, diaper backsheet, medical fabric, surgical wrap, hospital gown, wipe, textile, and geotextile. 25 The present invention further provides a process for making the non-woven fabric according to the invention, comprising providing the fibers according to the fibers and bonding the fibers to obtain the non-woven fabric. 30 The present invention further provides use of LDPE having a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min for improving smoothness of a non-woven fabric comprising a bicomponent fiber having a core- sheath configuration, wherein the core comprises a polypropylene composition and the sheath comprises a first polyethylene composition and a second polyethylene 35 composition, wherein the first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min and Classification: General Business Use 22POLY0027-WO-PCT 8 comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE) and the second polyethylene composition comprises the LDPE. It is noted that the invention relates to the subject-matter defined in the independent 5 claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the 10 composition according to the invention and features relating to the process according to the invention are described herein. It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a 15 product/composition comprising certain components also discloses a product/composition consisting of these components. The product/composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product/composition. Similarly, it is also to be understood that a description on a process comprising certain steps also 20 discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process. When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper 25 limit are also understood to be disclosed. The invention is now elucidated by way of the following examples, without however being limited thereto. 30 Materials Classification: General Business Use 22POLY0027-WO-PCT 9 Table 1 MFI of PP was measured according to ISO1133-1:2011 at 230 ⁰C and 2.16 kg; MFI of PE was measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg. Dow Aspun 6834 and Dow Aspun 6850 are polyethylene materials commercially 5 available from Dow as a fiber grade resin. PP1, HDPE1, HDPE2, Dow Aspun 6834 and 6850 and LLDPE1 comprise standard stabilizers. Bicomponent fibers having a core-sheath configuration and spunbond nonwoven 10 fabrics were produced using the materials of Table 1. Process conditions were set according to Table 2 such that bicomponent fibers are obtained from the compositions of Table 3 and spunbond nonwovens of around 20 gsm are produced from the obtained fibers. 15 Spinnability of the fibers is indicated in Table 2 as well as whether dripping problems occurred during spinning. Following properties were measured for the obtained spunbond nonwoven fabrics and are shown in Table 3: Tensile strength in machine direction (MD) and cross direction (CD) measured in 20 accordance with ASTM D5035-11 Classification: General Business Use 22POLY0027-WO-PCT 10 Elongation in machine direction (MD) and cross direction (CD) measured in accordance with ASTM D5035-11 Smoothness measured by standards in the TSA (tissue softness analyzer) Leaflet Collection No.11 of 13 Nov.2014 issued by emtec Electronic GmbH, Leipzig, DE.

⁰ ₃ ⁰ ₃ ⁰ _{3 5} ² _{5 1} ² _{5 1} ² _{1 5} ³ _{5 5 1} ³ ₁ ³ _{1 8} ² ₈ ² _{8 1 1} ² _{1 8} ³ _{8 8 1} ³ ₁ ³ _{1 0} ⁵ _{0 0 5} ⁵ ₅ ⁵ ₅ 8₅ ⁸ ₅ ⁸ _{5 s} ^e _s ^e _{s y y} ^e _{y 0} ⁴ ₀ ⁴ _{0 5 5} ⁴ _{5 3} ^. _{3 1} ^. _{3 1} ^. ₁ 1 _{6 1} ^. _{6 6 5} ^. ₅ ^. ₅ 1₁ ¹ ₁ ¹ ₁ 0₀ ^{0 0} ₀ ⁰ _{0 1} ⁰ ₁ ⁰ _{1 6} ^. _{6 0} ^. _{6 0} ^. ₀ ^e _s ^U _{0 0 s} ^{5 5} ₀ ^s _{2 2} ⁵ _{2 e} ⁿⁱ _{T s} C P ^u -_B O ₅ ⁴ ₅ ⁴ ₅ ^{l W} _{- 2 2} ⁴ _a ^{r 7} _{2 e 2} ^{n 0} _{0 e} ^Y _{L 3 4 5} ^{G 1 1 1} _: ^O P ^{x x x n 2} _{2 E E E oi} ^t _a ^ci _fi ^s _s ^al _C ³ _. ^{4 1} _{. 7} ⁹ ₈ o _n ^o _n d_o ^{d o} _{o g} ^o _{g 1} ⁷ _{9 .} ^{5 7} _{. 8} ⁰ _{8 3} ⁵ _{5 .} ^{2 8} _{. 7} ⁷ ₃ 1_. ⁴ _{9 2} ³ _. ¹ _{2 7} ⁰ _{5 .} ^{8 0} _{. 4} ¹ ₃ 3_. ^{5 0} _{. 2} ⁹ ₁ %⁶ % 1 ⁴ ₁ 2₁ ^e _s ^U _s ^% ₄ ^% ₆ ^s _e ⁿⁱ _{T s} C P % %^u - ⁰ ₈ ⁰ _B O ₈ ^l _a ^W-^{r 7} _{e 2} ^{n 0} _{0 e} ^Y _{4 5 L e} ^{l x} E ^x E ^x E ^x E ^x E ^x E ^{x x x x x 1 1 G} _: ^{O n} _{P b} C C C C C C _E C _E C _E C _E C _E C ^x E ^x E ^x E ^x E _o ² _i ^t ₂ ^a _{T a} ^ci _fi ^s _s ^al _C Classification: General Business Use 22POLY0027-WO-PCT 13 It can be understood that non-woven fabrics made of bicomponent fibers having a PP core/ PE sheath configuration (CEx 2-11 and Ex 12-15) have a better smoothness than that made of fibers made only from PP (CEx 1). 5 When the sheath was made of DOW ASPUN 6850 or 6834 (CEx 2-3), the fibers had good spinnability and no dripping problem occurred. However the non-woven fabric did not show a good smoothness. 10 When the sheath was made of LDPE2-4 (CEx 4-6), the fibers had good spinnability and no dripping problem occurred. The non-woven fabric showed a good smoothness. However the fibers exhibited poor bonding and the non-woven fabric had low mechanical properties. 15 When the sheath was made of LDPE1 having a relatively low MFI (CEx 7), the fibers had poor spinnability and dripping problem occurred. When the sheath was made of LLDPE1 (CEx 8 and CEx 11), the fibers had good spinnability but dripping problem occurred. The addition of LDPE4 to LLDPE1 (Ex 12) 20 solved this dripping problem. The non-woven fabric of Ex 12 showed sufficiently high mechanical properties and very good smoothness. When the sheath was made of HDPE1 having a relatively low MFI (CEx 10), the fibers had poor spinnability and dripping problem occurred. 25 When the sheath was made of HDPE2 (CEx 9), the fibers had good spinnability but dripping problem occurred. The addition of LDPE4 to HDPE2 (Ex 13-15) solved this dripping problem. The non-woven fabric showed of Ex 13-15 sufficiently high mechanical properties and very good smoothness. In particular, Ex 14 in which 16% 30 HDPE / 4% LDPE was used led to outstanding results. It was accordingly found that the addition of LDPE to HDPE or LLDPE in the sheath of the fiber was found to substantially improve the processibility of the polyethylene composition and prevents dripping during the production of the fiber. The non-woven 35 fabric has an excellent smoothness.

Claims

Classification: General Business Use 22POLY0027-WO-PCT 14 CLAIMS 1. A bicomponent fiber having a core-sheath configuration, wherein the core comprises a polypropylene composition and 5 the sheath comprises a first polyethylene composition and a second polyethylene composition, wherein the first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min and comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE) and 10 the second polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min, wherein the second polyethylene composition comprises low density polyethylene (LDPE), wherein the LDPE has a density measured according to ISO1183 of 910-940 kg/m³. 15 2. The bicomponent fiber according to claim 1, wherein the LDPE has a density measured according to ISO1183 of 913-935 kg/m³, preferably 915-925 kg/m³, preferably wherein the LDPE is an ethylene homopolymer. 20 3. The bicomponent fiber according to any one of the preceding claims, wherein the melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of the first polyethylene composition is 7.5 to 10 dg/min. 4. The bicomponent fiber according to any one of the preceding claims, wherein the 25 first polyethylene composition comprises the HDPE and the HDPE has density measured according to ISO1183 of 941-970 kg/m³, more preferably 950-967 kg/m³, more preferably 960-967 kg/m³, preferably wherein the HDPE is an ethylene homopolymer. 30 5. The bicomponent fiber according to any one of the preceding claims, wherein the first polyethylene composition comprises the LLDPE and the LLDPE has a density m^{easured according to ISO1183 of of 910-940 kg/m3} _{, more preferably 920-940} kg/m³, more preferably 925-935 kg/m³, preferably wherein the LLDPE is a copolymer of ethylene and 1-butene, preferably wherein the amount of units 35 derived from 1-butene in the copolymer is 1.0 to 5.0 wt%. Classification: General Business Use 22POLY0027-WO-PCT 15 6. The bicomponent fiber according to any one of the preceding claims, wherein the weight ratio between the first polyethylene composition and the second polyethylene composition is 95:5 to 60:40, preferably 90:10 to 70:30. 5 7. The bicomponent fiber according to any one of the preceding claims, wherein the weight ratio between the first polyethylene composition and the second polyethylene composition is 85:15 to 75:25. 8. The bicomponent fiber according to any one of the preceding claims, wherein the 10 weight ratio between the core and the shell is 85:15 to 40:60, for example 80:20 to 50:50. 9. A process for making the fiber according to any one of the preceding claims, comprising the steps of providing a melt of the polypropylene composition and a 15 melt of the first polyethylene composition and the second polyethylene composition and extruding the melt of the polypropylene composition and the melt of the first polyethylene composition and the second polyethylene composition through a spinneret to obtain the fiber. 20 10. A non-woven fabric comprising the fiber according to any one of claims 1-8. 11. The non-woven fabric according to claim 10, wherein the non-woven fabric has a smoothness determined according to standards in the TSA (tissue softness analyzer) Leaflet Collection No.11 of 13 Nov.2014 issued by emtec Electronic 25 GmbH, Leipzig, DE of at most 110, more preferably at most 104, more preferably at most 95. 12. A process for making the non-woven fabric according to claim 10 or 11, comprising providing the fibers according to any one of claims 1-9 and bonding the fibers to 30 obtain the non-woven fabric. 13. An article comprising the non-woven fabric according to claim 10 or 11, preferably wherein said article is selected from the group consisting of upholstery, apparel, wall covering, carpet, diaper topsheet, diaper backsheet, medical fabric, surgical 35 wrap, hospital gown, wipe, textile, and geotextile. Classification: General Business Use 22POLY0027-WO-PCT 16 14. Use of LDPE having a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 15 to 50 dg/min for improving smoothness of a non-woven fabric comprising a bicomponent fiber having a core-sheath configuration, wherein the core comprises a polypropylene composition and the sheath comprises a first 5 polyethylene composition and a second polyethylene composition, wherein the first polyethylene composition has a melt flow index measured according to ISO1133-1:2011 at 190 ⁰C and 2.16 kg of 5.0 to 14 dg/min and comprises high density polyethylene (HDPE) and/or linear low density polyethylene (LLDPE) and the second polyethylene composition comprises the LDPE. 10