Bicomponent fiber

Abstract

The invention relates to a bicomponent fiber comprising a first component comprising a first polypropylene homopolymer and a second component comprising a second polypropylene homopolymer and an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof, wherein the amount of said additive with respect to the second component is 50 to 3000 ppm, wherein the first component has a melt flow index MFI1 determined according to ISO 1133-1:2011 at 230 ⁰C and 2.16 kg and the second component has a melt flow index MFI2 determined according to ISO 1133-1:2011 at 230 ⁰C and 2.16 kg of MFI2 and the difference between MFI1 and MFI2 is 0.0 to 25.0 dg / min.

Description

[0001] BICOMPONENT FIBER

[0002] 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 for making such non-woven fabric and an article comprising such non-woven fabric.

[0003] Polypropylene (PP) nonwoven fabrics are widely applied in hygiene, healthcare and medical fields, e.g., diapers, incontinence pads, sanitary wipes and surgical gowns and drapes, due to its roust mechanical properties over a variety range of processing conditions such as spunbond technology. However, traditional PP nonwovens often lack a good hand-touch feeling like natural fibers and fabrics (cotton), which originates from an absence of a crimped structure of PP fibers, as well as the “loft” or “bulk” space-filling characteristics of PP fibers. Currently, there is a greatly increasing demand for bulky and soft nonwovens in the hygiene market, and bicomponent spunbond process has demonstrated some advantages to impart “loft” properties to PP nonwovens in a cost-effective way, compared to staple fiber process.

[0004] WO2016 / 073713 discloses a crimped fiber spunbond nonwoven web made from bicomponent fibers. Figure 64 shows a graph depicting stress strain curves for spunbond nonwoven webs made from monocomponent fibers and bicomponent fibers. The spunbond nonwoven webs 6410 and 6420 were made from side-by-side configured bicomponent fibers where the first component of the bi-component fiber was a polypropylene from Lyondell Basell HP561 R and the second component was also a polypropylene from Lyondell Basell HP552R, both having an MFR of 25 dg / min (230 °C, 2.16 kg). The first and second components both comprised Techmer PPM17000 High Load Hydrophobic masterbatch. The second component additionally comprised 1% or 1.5% TiO2.

[0005] There is still a need for a non-woven fabric having a good skin-touch feeling such as loft and elastic properties.

[0006] It is an objective of the present invention to provide a fiber by which the above- mentioned and / or other needs are met.

[0007] Accordingly, the present invention provides a bicomponent fiber comprising a first component comprising a first polypropylene homopolymer and a second component comprising a second polypropylene homopolymer and an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof, wherein the amount of said additive with respect to the second component is 50 to 3000 ppm, wherein the first component has a melt flow index MFI1 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg and the second component has a melt flow index MFI2 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of MFI2 and the difference between MFI1 and MFI2 is 0.0 to 25.0 dg / min.

[0008] The invention further provides a non-woven fabric comprising the fiber according to the invention.

[0009] It was surprisingly found that the non-woven fabric according to the invention has a high loft represented by a high thickness and good elastic properties represented by a high elongation.

[0010] Bicomponent fiber

[0011] The fiber according to the invention may be a bicomponent fiber of any type, including core-sheath types, side-by-side types, hollow side-by-side types, island in sea types, layered types, as well as others, including modifications, such as eccentric core-sheath types.

[0012] Preferably, the bicomponent fiber according to the invention has a core-sheath configuration or a side-by-side configuration, most preferably a side-by-side configuration.

[0013] Preferably, the bicomponent fiber according to the invention consists of the first polymer component and the second polymer component.

[0014] Preferably, the weight ratio between the first component and the second component is 95:5 to 5:95, for example 90:10 to 10:90, 85:15 to 20:80, 85:15 to 30:70 or 85:15 to 35:65.

[0015] The bicomponent fiber according to the present invention may be prepared in any desired thickness depending upon the desired end use. Typical thicknesses are known to the skilled person and the fibers may have a linear mass density of e.g. 0.5 to 100 denier, such as 1 .0 to 50 denier.

[0016] First component

[0017] The first component of the bicomponent fiber has a melt flow index MFI1 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg.

[0018] Preferably, MFI1 is 5.0 to 50 dg / min, for example 10 to 40 dg / min. This is beneficial for the mechanical properties of the non-woven fabric such as tensile strength. In some preferred embodiments, MFI1 is 15 to 35 dg / min or 20 to 30 dg / min. In some preferred embodiments, MFI1 is more than 30 dg / min and at most 40 dg / min.

[0019] The first polypropylene homopolymer may have a melt flow index determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of 5.0 to 50 dg / min, for example 10 to 40 dg / min. This is beneficial for the mechanical properties of the non-woven fabric such as tensile strength. In some preferred embodiments, the first polypropylene homopolymer has a melt flow index determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of 15 to 35 dg / min or 20 to 30 dg / min. In some preferred embodiments, the first polypropylene homopolymer has a melt flow index determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of more than 30 dg / min and at most 40 dg / min.

[0020] Preferably, the first polypropylene homopolymer has Z-average molecular weight Mz of 300,000 to 600,000, more preferably 350,000 to 500,000, more preferably 380,000 to 500,000, more preferably 400,000 to 480,000.

[0021] Preferably, the first polypropylene homopolymer has weight average molecular weight Mw of 150,000 to 250,000, more preferably 170,000 to 230,000, more preferably 170,000 to 200,000.

[0022] Preferably, the first polypropylene homopolymer has Mn of 10,000 to 60,000, more preferably 20,000 to 50,000, more preferably 42,000 to 50,000.

[0023] Preferably, the first polypropylene homopolymer has Mz / Mw of at most 2.50, more preferably 1 .50 to 2.50, more preferably 1 .70 to 2.40.

[0024] Preferably, the first polypropylene homopolymer has Mw / Mn of 2.0 to 5.0, more preferably 2.5 to 4.5, more preferably 3.6 to 4.4. The first component further may comprise additives such as stabilizers, 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 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 to 5.0 wt%.

[0025] In some embodiments, the first component is substantially free of an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative. In some embodiments, the first component does not comprise an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative or the first component comprises less than 50 ppm, less than 30 ppm, less than 10 ppm of an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof.

[0026] The amount of the first polypropylene homopolymer with respect to the first component may 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 the first polypropylene homopolymer and the additives is 100 wt% with respect to the first component.

[0027] Second component

[0028] The second component of the bicomponent fiber has a melt flow index MFI2 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg.

[0029] Preferably, MFI2 is 5.0 to 50 dg / min, for example 7.0 to 40 dg / min, 10 to 30 dg / min or 15 to 25 dg / min. This is beneficial for the mechanical properties of the non-woven fabric such as tensile strength.

[0030] The second component comprises a second polypropylene homopolymer.

[0031] The second polypropylene homopolymer may have a melt flow index determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of 5.0 to 50 dg / min, for example 7.0 to 40 dg / min, 10 to 30 dg / min or 15 to 25 dg / min. Preferably, the second polypropylene homopolymer has Z-average molecular weight Mz of 550,000 to 750,000, more preferably 600,000 to 650,000. Mz of the second polypropylene homopolymer may be higher than Mz of the first polypropylene homopolymer.

[0032] Preferably, the second polypropylene homopolymer has weight average molecular weight Mw of 150,000 to 300,000, more preferably 170,000 to 270,000, more preferably 200,000 to 250,000. Mw of the second polypropylene homopolymer may be higher than Mw of the first polypropylene homopolymer.

[0033] Preferably, the second polypropylene homopolymer has number average molecular weight Mn of 10,000 to 60,000, more preferably 20,000 to 50,000, more preferably 42,000 to 50,000.

[0034] Preferably, the second polypropylene homopolymer has Mz / Mw of 2.40 to 3.00, more preferably 2.50 to 2.90, more preferably 2.55 to 2.80. Mz / Mw of the second polypropylene homopolymer may be higher than Mz / Mw of the first polypropylene homopolymer.

[0035] Preferably, the second polypropylene homopolymer has Mw / Mn of 3.0 to 6.0, preferably 4.5 to 5.5. Mw / Mn of the second polypropylene homopolymer may be higher than Mw / Mn of the first polypropylene homopolymer.

[0036] The second component comprises an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof.

[0037] The amount of the additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof with respect to the second component is 50 to 3000 ppm, for example 100 to 2000 ppm or 150 to 1200 ppm.

[0038] Preferably, the amount of the additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof with respect to the bicomponent fiber is 10 to 1500 ppm or 50 to 500 ppm In some preferred embodiments, the additive comprises or is talc and the amount of the talc with respect to the second component is 50 to 1200 ppm, preferably 100 to 1000 ppm, more preferably 200 to 800 ppm.

[0039] The talc may have D50 of e.g. less than 1 .0 pm or 1 .0 to 20 pm. Suitable commercially available examples of the talc include Luzenac 10M00S by Imerys having D50 of less than 1 .0 pm and Prever M30 having D50 of 5-15 pm.

[0040] In some preferred embodiments, the additive comprises or is the cyclic dicarboxylate salt compound and the amount of the cyclic dicarboxylate salt compound with respect to the second component is 100 to 500 ppm.

[0041] Preferably, the cyclic dicarboxylate salt compound is a bicyclic dicarboxylate metal salt, for example disodium bicyclo[2.2.1]heptane-2,3- dicarboxylate (commercially available as HPN-68 or HPN-68L from Milliken) or calcium bicyclo[2.2.1]heptane-2,3- dicarboxylate. More preferably, the cyclic dicarboxylate salt compound is a cyclic dicarboxylate salt compoundtiaving the formula:

[0042] This cyclic dicarboxylate salt compound is commercially available as Hyperform® HPN® 20E.

[0043] In some preferred embodiments, the additive comprises or is the phosphoric acid ester compound and the amount of the phosphoric acid ester compound with respect to the second component is 500 to 1500 ppm.

[0044] Preferably, the phosphoric acid ester compound ^represented by the following general formula: wherein R1to R4each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 9 carbon atoms, and R5represents an alkylidene group having 1 to 4 carbon atoms.

[0045] Examples of the linear or branched alkyl group having 1 to 9 carbon atoms represented by R1to R4in the general formula (1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an amyl group, a tert-amyl group, a hexyl group, a heptyl group, an octyl group, an isooctyl group, a tert-octyl group, a 2-ethylhexyl group, a nonyl group, and an isononyl group, and R' to R4are preferably tert-butyl group.

[0046] Examples of the alkylidene group having 1 to 4 carbon atoms represented by

[0047] R5include a methylene group, an ethylidene group, a propylidene group, and a butylidene group, and in the resin composition of the present invention, a methylene group is preferred.

[0048] Specific examples of the phosphoric acid ester compoundinclude compounds below:

[0049]

[0050] Most preferably, the phosphoric acid ester compound is sodium [2,2'-methylenebis(4,6- di-tert-butylphenyl)phosphate]. This phosphoric acid ester compound is commercially available as ADK STAB NA-11 .

[0051] In some preferred embodiments, the additive comprises or is the sorbitol derivative and the amount of the sorbitol derivative with respect to the second component is 1000 to 3000 ppm.

[0052] Preferably, the sorbitol derivative is selected from the group consisting of dimethyldibenzylidene sorbitol and 1 ,2,3-tridesoxy-4,6;5,7-bis-0-[(4-propylphenyl) methylene] nonitol sorbitol. This sorbitol derivative is commercially available as Millad® NX8000 from Milliken.

[0053] The second component may comprise further additives in addition to the additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof. Examples of the further additives include stabilizers, 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. The amount of the further additives may e.g. be 0.0-5.0 wt% with respect to the second component.

[0054] The amount of the second polypropylene homopolymer with respect to the second component may e.g. be at least 95 wt%, at least 98 wt%, at least 99 wt%, at least 99.5 wt%, at least 99.6 wt%, at least 99.7 wt%, at least 99.8 wt% or at least 99.9 wt%.

[0055] Preferably, the total amount of the second polypropylene homopolymer, the additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof and the further additives is 100 wt% with respect to the second component.

[0056] Preferably, the second component is substantially free of a triglyceride ester. Preferably, the second component comprises less than 1 .0 wt% preferably less than 0.1 wt% of a triglyceride ester with respect to the second component.

[0057] First component versus second component

[0058] The difference between MFI1 and MFI2 is 0.0 to 25 dg / min, for example 0.0 to 10.0 dg / min or more than 10.0 dg / min and at most 25.0 dg / min.

[0059] In some embodiments, the difference between MF1 and MFI2 is small or none. Accordingly, in some embodiments, the difference between MFI and MFI2 is less than 0.1 dg / min and / or the ratio of MFI1 to MFI2 is 0.99 to 1 .01 .

[0060] Preferably, MFI1 and MFI2 are selected differently. Accordingly, in some preferred embodiments, the difference between MFI1 and MFI2 is 0.1 to 25.0 dg / min, preferably 1 .0 to 23 dg / min, more preferably 2.0 to 20.0 dg / min, more preferably 3.0 to 19.0 dg / min, more preferably 4.0 to 18.0 dg / min. The ratio of MFI1 to MFI2 may e.g. be 0.45 to 0.99 or 1.01 to 1.95. The ratio of MFI1 to MFI2 may e.g. be 0.45 to 0.90 or 1.10 to 1 .95. Advantageously, this results in a lower density of the non-woven fabric made from the fibers according to the invention.

[0061] In some preferred embodiments, the difference between MFI1 and MFI2 is 0.1 to 10.0 dg / min, preferably 1 .0 to 10.0 dg / min, 2.0 to 9.0 dg / min, 3.0 to 8.0 dg / min or 4.0 to 7.0 dg / min. The ratio of MFI1 to MFI2 may e.g. be 0.70 to 0.99 or 1.01 to 1.40. The ratio of MFI1 to MFI2 may e.g. be 0.70 to 0.90 or 1.10 to 1.40. In some preferred embodiments, the difference between MFI1 and MFI2 is more than 10.0 dg / min and at most 25.0 dg / min, preferably 11.0 to 23.0 dg / min, 12.0 to 20.0 dg / min or 13.0 to 19.0 dg / min. The ratio of MFI1 to MFI2 may e.g. be 0.45 to 0.70 or 1 .40 to 1 .95. The ratio of MFI1 to MFI2 may e.g. be 0.50 to 0.65 or 1 .70 to 1 .90.

[0062] MFI2 is smaller than, equal to or greater than MFI1. Preferably, MFI2 is smaller than MFI1.

[0063] In some embodiments, the difference between Mw / Mn of the first polypropylene homopolymer and Mw / Mn of the second polypropylene homopolymer is less than 0.1.

[0064] Preferably, Mw / Mn of the first polypropylene homopolymer is lower than Mw / Mn of the second polypropylene homopolymer.

[0065] Preferably, the difference between Mw / Mn of the first polypropylene homopolymer and Mw / Mn of the second polypropylene homopolymer is 0.1 to 3.0, for example 0.2 to 2.5, 0.3 to 2.0 or 0.5 to 1 .5. Advantageously, this results in a lower density of the nonwoven fabric made from the fibers according to the invention.

[0066] Z-average molecular weight Mz, weight average molecular weight Mw and number average molecular weight Mn may be measured by Gel Permeation Chromatography, e.g. according to 18016014-1(2012). For calibration polystyrene standards may be used with Mark-Houwink correction.

[0067] Other aspects

[0068] 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 first component and a melt of the second component and extruding the melt of the first component and the melt of the second component through a spinneret to obtain the bicomponent fiber.

[0069] In the context of the present invention, the term “polypropylene homopolymer” refers to a polypropylene polymer comprising less than 0.3% comonomer, wherein the comonomer may be derived from ethylene or 1 -butene or 1 -hexene, preferably said polypropylene polymer is essentially free of comonomer, more preferably said polypropylene polymer consists of propylene unit. 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 30 gsm.

[0070] 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.

[0071] The present invention further provides a process for making the non-woven fabric according to the invention, comprising a) providing the fibers according to the fibers and b) bonding the fibers to obtain the non-woven fabric.

[0072] Preferably, step b) comprises calendering or hot air through bonding, more preferably calendering. The calendering preferably involves the use of semi-high loft calender over high loft calender for calendering. Semi-high loft calender is used for obtaining a structure in which a crimpled high loft spunbond layer is provided on an uncrimped or low crimped spunbond layer. High loft calender is used for obtaining a structure in which all layers are crimped.

[0073] It is noted that the invention relates to the subject-matter defined in the independent 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 composition according to the invention and features relating to the process according to the invention are described herein.

[0074] 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 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 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.

[0075] 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 limit are also understood to be disclosed.

[0076] The invention is now elucidated by way of the following examples, without however being limited thereto.

[0077] Materials

[0078] Following propylene homopolymers were used:

[0079] Table 1

[0080] MFR: ISO1133-1 :2011 at 230 °C and 2.16 kg

[0081] Mz, Mw, Mn: Gel Permeation Chromatography according to ISO16014-1 (2012)

[0082] Luzenac 10: talc with D50 < 1.0 pm

[0083] Prever M30: talc with D50 of 5-15 pm

[0084] HPN20E: Hyperform® HPN® 20E available from Milliken

[0085] NA-11 : ADK STAB NA-11 available from Adeka

[0086] NX8000: Millad® NX® 8000 available from Milliken

[0087] Experiment set 1

[0088] Bicomponent fibers having a side-to-side configuration and non-woven fabrics using these fibers were produced using the materials of Table 2.

[0089] The spunbound line used in the experiments consists of two single screw extruders A and B. Extruder A has 5 heating zones, a diameter of 2.5” and a L / D ratio of 30. Extruder B has 4 heating zones, a diameter of 2.0” and a L / D ratio of 30. Spinning pumps are used to feed the molten polymer to the line spinpack which consists of 1003 holes in side-by-side configuration through a 90 pm filter. The line was operated using the following settings:

[0090] Melt temperature A [°C] 244

[0091] Melt temperature B [°C] 244

[0092] Throughput per hole [g / min] 0.6 Spinning distance [mm] 950

[0093] Quench temperature [°C] 13

[0094] Fibre gap [mm] 6.5

[0095] Air pressure [bars] 1 .5

[0096] Laying distance [mm] 570

[0097] Compaction roll yes / no 0

[0098] Outlet speed [mpm] 29.8

[0099] Outlet web width [mm] 550 line speed [mpm] 30

[0100] Spunbond nonwoven fabrics were produced using the spun bicomponent fibers by hot air through bonding. The temperature of air-through bonding was 180°C and there were 5 different zones of air-through bonding each with a working length of 2 meters.

[0101] The basis weight and thickness of the nonwoven fabrics were measured and the results are shown in Table 2. The density and the softness of the nonwoven fabrics were also measured. The softness (TS7) was measured by a tissue softness analyzer.

[0102] Table 2

[0103] In Ex 1-20, the values of TS7 softness were 20 to 50% of that of CEx 21 which was 22.6. In Ex 1-20, the values of the densities were lower than or comparable with that of CEx 21 which was 47 kg / m3.

[0104] It was observed that the densities were lower in the examples where the second component comprise two types of polypropylene homopolymer with different MFI and Mw / Mn than the examples where the second component comprise one type of polypropylene homopolymer when the amounts of talc are comparable.

[0105] Best balance of softness and density was observed when the additive was talc, followed by HPN20E and NZ8000, followed by NA-11.

[0106] Experiment set 2

[0107] Bicomponent fibers having a side-to-side configuration and non-woven fabrics using these fibers were produced using the process parameters shown in Table 3.

[0108] The spunbound line used in the experiments comprises two single screw extruders. Spinning pumps were used to feed the molten polymer to the spinpack line which consists of 7377 holes in side-by-side configuration. Spunbond nonwoven fabrics were produced using the obtained spun bicomponent fibers by calendering (semi-high loft calendering).

[0109] Table 3. Process parameters

[0110] Various properties of the spunbond nonwoven fabrics produced were measured and are shown in Table 4.

[0111] Tensile strength in machine direction (MD) and cross direction (CD) was measured in accordance with ASTM D5035-11 .

[0112] Elongation in machine direction (MD) and cross direction (CD) was measured in accordance with ASTM D5035-11

[0113] Table 4

[0114] Table 4 It can be understood that the use of two components in making the fibers according to the invention resulted in higher elongation and higher thickness of the spunbond nonwoven fabrics than the use of one component in making the fibers. The weight ratio of PP511A:PP576P of 90:10 and 80:20 resulted in particularly high thickness. The weight ratio of PP519A:PP576P is around 90:10 and 80:20 resulted in particularly high thickness. The softness of the fabric according to the invention was sufficiently high. The air permeability of the fabric according to the invention was sufficiently high.

Claims

CLAIMS1. A bicomponent fiber comprising a first component comprising a first polypropylene homopolymer and a second component comprising a second polypropylene homopolymer and an additive selected from the group consisting of talc, a cyclic dicarboxylate salt compound, a phosphoric acid ester compound and a sorbitol derivative and combinations thereof, wherein the amount of said additive with respect to the second component is 50 to 3000 ppm, wherein the first component has a melt flow index MFI1 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg and the second component has a melt flow index MFI2 determined according to ISO 1133-1 :2011 at 230 °C and 2.16 kg of MFI2 and the difference between MFI1 and MFI2 is 0.0 to 25.0 dg / min.

2. The bicomponent fiber according to claim 1 , wherein the difference between MFI1 and MFI2 is 0.1 to 25.0 dg / min, preferably 1 .0 to 23 dg / min, more preferably 2.0 to 20.0 dg / min, more preferably 3.0 to 19.0 dg / min, more preferably 4.0 to 18.0 dg / min, preferably wherein MFI1 is higher than MFI2.

3. The bicomponent fiber according to any one of the preceding claims, wherein MFI1 is 5.0 to 50 dg / min, for example 10 to 40 dg / min, for example 15 to 35 dg / min or 20 to 30 dg / min or for example more than 30 dg / min and at most 40 dg / min and / or MFI2 is 5.0 to 50 dg / min, for example 7.0 to 40 dg / min, 10 to 30 dg / min or 15 to 25 dg / min.

4. The bicomponent fiber according to any one of the preceding claims, wherein the difference between Mw / Mn of the first polypropylene homopolymer and Mw / Mn of the second polypropylene homopolymer is 0.1 to 3.0, for example 0.2 to 2.5, 0.3 to 2.0 or 0.5 to 1 .5, preferably wherein Mw / Mn of the first polypropylene homopolymer is lower than Mw / Mn of the second polypropylene homopolymer.

5. The bicomponent fiber according to any one of the preceding claims, wherein the first polypropylene homopolymer has Mw / Mn of 3.0 to 6.0, preferably 3.5 to 4.4 and / or the second polypropylene homopolymer has Mw / Mn of 3.0 to 6.0, preferably 4.5 to 5.5.

6. The bicomponent fiber according to any one of the preceding claims, wherein said additive comprises or is talc.

7. The bicomponent fiber according to claim 6, wherein the amount of the talc with respect to the second component is 50 to 1200 ppm, preferably 100 to 1000 ppm, more preferably 200 to 800 ppm.

8. The bicomponent fiber according to any one of the preceding claims, wherein the weight ratio between the first component to the second component is 95:5 to 5:95, for example 90:10 to 10:90, 85:15 to 20:80, 85:15 to 30:70 or 85:15 to 35:65.

9. The bicomponent fiber according to any one of the preceding claims, wherein the bicomponent fiber has a core-sheath configuration or a side-by-side configuration, preferably a side-by-side configuration.

10. A process for making the bicomponent fiber according to any one of the preceding claims, comprising the steps of: providing a melt of the first component and a melt of the second component and extruding the melt of the first component and the melt of the second component through a spinneret to obtain the bicomponent fiber.

11. A non-woven fabric comprising the fiber according to any one of claims 1-10.

12. A process for making the non-woven fabric according to claim 11 , comprising a) providing the fibers according to any one of claims 1-10 and b) bonding the fibers to obtain the non-woven fabric.

13. The process according to claim 12, wherein step b) comprises calendering or hot air through bonding.

14. The process according to claim 12, wherein step b) comprises calendering.

15. An article comprising the non-woven fabric according to claim 11 , preferably wherein said 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.

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