NONWOVEN FABRIC AND PROCESS FOR THE PRODUCTION THEREOF

Abstract

The present invention relates to a process for the production of a nonwoven fabric. In particular, the present invention relates to the production of a nonwoven fabric having desirable tactile and haptic properties, as well as to the nonwoven fabric itself. The process requires the selection of specific materials and process conditions. The fabric is produced from a masterbatch of isotactic polypropylene homopolymer and a surface-treated calcium carbonate filler.

Claims

1.-15. (canceled)

16. A process for producing a nonwoven fabric, the process comprising the following steps: a) providing a surface-treated calcium carbonate-containing filler material, the surface-treated calcium carbonate-containing filler material comprising a calcium carbonate-containing filler material having prior to the surface treatment i) a weight median particle size (d.sub.50) value in the range from 0.1 μm to 7 μm, ii) a top cut (d.sub.98) value of 15 μm or less, iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and iv) a residual total moisture content from 0.01 wt.-% to 1 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material, and a surface-treatment layer on at least a part of the surface of the calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 3 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material, and wherein the surface treatment agent comprises at least one carboxylic acid and/or a salt or anhydride thereof, b) providing a first polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011, c) providing a second polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011, d) forming a masterbatch by compounding the surface-treated calcium carbonate-containing filler material of step a) in an amount of 60 wt.-% to 75 wt.-%, based on the total weight of the masterbatch, with the first polypropylene polymer of step b), e) mixing the masterbatch of step d) with the second polypropylene polymer of step c) to obtain a mixture having a surface-treated calcium carbonate-containing filler material content in the range of 5 wt.-% to 15 wt.-%, based on the total weight of the mixture, f) forming the mixture of step e) into fibers having an average fiber diameter in the range from 11 to 30 μm, g) forming a fibrous web from the fibers of step f), and h) forming the non-woven fabric by hydroentanglement of the fibrous web of step g), wherein the water pressure during hydroentanglement step h) does not exceed 170 bar and wherein the final bonding step during hydroentanglement is carried out at a water pressure in the range of 80 to 170 bar.

17. The process of claim 16, wherein the nonwoven fabric has a water vapor transmission rate of at least 1000 g/(m.sup.2 day), measured according to ASTM E398-13.

18. The process of claim 16, wherein the nonwoven fabric has a water vapor transmission rate of at least 3000 g/(m.sup.2 day), measured according to ASTM E398-13.

19. The process of claim 16, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a calcium carbonate-containing filler material having prior to the surface treatment i) a weight median particle size (d.sub.50) value in the range from 0.25 μm to 5 μm, and/or ii) a top cut (d.sub.98) value of 15 μm or less, and/or iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and/or iv) a residual total moisture content from 0.01 wt.-% to 0.2 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material.

20. The process of claim 16, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a calcium carbonate-containing filler material having prior to the surface treatment i) a weight median particle size (d.sub.50) value in the range from 1.0 to 3.5 μm, and/or ii) a top cut (d.sub.98) value of 7.5 μm or less, and/or iii) a specific surface area (BET) from 0.5 to 15 m.sup.2/g, as measured by the BET method, and/or iv) a residual total moisture content from 0.02 wt.-% to 0.15 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material.

21. The process of claim 16, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a surface-treatment layer on at least a part of the surface of the calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 2.5 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material.

22. The process of claim 16, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a surface-treatment layer on at least a part of the surface of the calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.2 to 0.8 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material.

23. The process of claim 16, wherein the surface treatment agent comprises at least one monocarboxylic acid and/or a salt or anhydride thereof.

24. The process of claim 16, wherein the surface treatment agent comprises stearic acid and/or a salt thereof.

25. The process of claim 16, wherein the surface treatment agent comprises at least one dicarboxylic acid and/or a salt or anhydride thereof.

26. The process of claim 16, wherein the surface treatment agent comprises at least one mono-substituted succinic anhydride.

27. The process of claim 16, wherein the first polypropylene polymer of step b) and/or the second polypropylene polymer of step c) is an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 20 to 35 g/10 min, as measured according to EN ISO 1133:2011.

28. The process of claim 16, wherein the first polypropylene polymer of step b) and/or the second polypropylene polymer of step c) is an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 25 to 35 g/10 min, as measured according to EN ISO 1133:2011 wherein the first polypropylene polymer of step b) and the second polypropylene polymer of step c) are the same polymer.

29. The process of claim 16, wherein the masterbatch is formed in step d) by compounding the surface-treated calcium carbonate-containing filler material of step a) in an amount of 65 wt.-% to 74 wt.-%, based on the total weight of the masterbatch, with the first polypropylene polymer of step b).

30. The process of claim 16, wherein the masterbatch is formed in step d) by compounding the surface-treated calcium carbonate-containing filler material of step a) in an amount of 68 wt.-% to 72 wt.-%, based on the total weight of the masterbatch, with the first polypropylene polymer of step b).

31. The process of claim 16, wherein the fibers formed in step f) are staple fibers having an average fiber diameter in the range from 14 to 30 μm, and/or a titer in the range from 1 to 6 dtex, as measured by EN ISO 2062:2009 and/or a staple fiber length in the range from 30 to 90 mm.

32. The process of claim 16, wherein the fibers formed in step f) are staple fibers having an average fiber diameter in the range from 14 to 25 μm, and/or a titer in the range from 1.5 to 4 dtex, as measured by EN ISO 2062:2009 and/or a staple fiber length in the range from 40 to 60 mm, wherein the staple fibers are formed from the mixture of step e) by a process comprising the steps of multifilament or monofilament extrusion and cutting, and/or wherein the staple fibers are formed into a fibrous web during step g) by carding.

33. The process of claim 16, wherein the fibers formed in step f) are filaments having an average fiber diameter in the range from 14 to 30 μm, and/or a titer in the range from 1 to 6 dtex, as measured by EN ISO 2062:2009.

34. The process of claim 16, wherein the fibers formed in step f) are filaments having an average fiber diameter in the range from 14 to 25 μm, and/or a titer in the range from 1.5 to 4 dtex, as measured by EN ISO 2062:2009, wherein the filaments are formed from the mixture of step e) by spunbonding and/or meltblowing.

35. The process of claim 16, wherein in hydroentanglement step h) the pre-bonding step is performed at a water pressure of 50 to 120 bar, and/or the water pressure does not exceed 160 bar, and/or the water pressure of the final bonding step is in the range of 90 to 160 bar, and/or at least 95% of the process water is reused, and/or the nonwoven fabric is dried after the final bonding step at a temperature below 135° C.

36. The process of claim 16, wherein in hydroentanglement step h) the pre-bonding step is performed at a water pressure of 65 to 105 bar, and/or the water pressure does not exceed 155 bar, and/or the water pressure of the final bonding step is in the range of 95 to 155 bar, and/or at least 99% of the process water is reused, and/or the nonwoven fabric is dried after the final bonding step at a temperature below 100° C.

37. A nonwoven fabric formed from fibers, wherein the fibers have an average fiber diameter in the range from 11 to 30 μm and are composed of a mixture comprising a first polypropylene polymer, being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011 a second polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011 and a surface-treated calcium carbonate-containing filler material, the surface-treated calcium carbonate-containing filler material comprising a calcium carbonate-containing filler material having prior to the surface treatment i) a weight median particle size (d.sub.50) value in the range from 0.1 μm to 7 μm, ii) a top cut (d.sub.98) value of 15 μm or less, iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and iv) a residual total moisture content of from 0.01 wt.-% to 1 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material, and a surface-treatment layer on at least a part of the surface of the calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 3 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material, and wherein the surface treatment agent comprises at least one carboxylic acid and/or a salt or anhydride thereof; wherein the surface-treated calcium carbonate-containing material is contained in the mixture in an amount from 5 wt.-% to 15 wt.-%, based on the total weight of the mixture, and wherein the nonwoven fabric has a water vapor transmission rate of at least 1000 g/(m.sup.2 day), measured according to ASTM E398-13.

38. The nonwoven fabric of claim 37, wherein the nonwoven fabric has a water vapor transmission rate of at least 2000 g/(m.sup.2 day), measured according to ASTM E398-13.

39. The nonwoven fabric of claim 37, wherein the nonwoven fabric has a water vapor transmission rate of at least 3000 g/(m.sup.2 day), measured according to ASTM E398-13.

40. An article comprising the nonwoven fabric as obtained in the process according to claim 16.

41. An article comprising the nonwoven fabric of claim 37.

Description

EXAMPLES

[0324] In the following, measurement methods and materials implemented in the examples are described.

Measurement Methods

Particle Size

[0325] The particle distribution of the calcium carbonate filler was measured using a Sedigraph 5120 from the company Micromeritics, USA. The method and the instruments are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement was carried out in an aqueous solution comprising 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high speed stirrer and supersonics.

Specific Surface Area

[0326] Throughout the present document, the specific surface area (in m.sup.2/g) is determined using the BET method (using nitrogen as adsorbing gas), which is well known to the skilled man (ISO 9277:2010). The total surface area (in m.sup.2) of the filler material is then obtained by multiplication of the specific surface area and the mass (in g) of the corresponding sample.

Total Moisture Content

[0327] The total moisture contents as defined herein are measured according to the Karl Fischer coulometric titration method, desorbing the moisture in an oven at 220° C. for 10 min and passing it continuously into a Karl Fischer coulometer (Mettler-Toledo coulometric KF Titrator C30, combined with Mettler-Toledo oven DO 0337) using dry nitrogen at 100 ml/min, e.g., for 10 min. A calibration curve using water is recorded and a blank of 10 min nitrogen flow without a sample is taken into account.

Titer or Linear density (Continuous Filaments)

[0328] The titer or linear density [dtex] was measured according to EN ISO 2062:2009 and corresponds to the weight in grams of 10 000 m fiber. A sample of 25 or 100 metres was wound up on a standard reel under a pretension of 0.5 cN/tex and weighted on analytical scale. The grams per 10 000 m fiber length were then calculated.

Fiber Diameter (Staple Fibers and Spunlaid Fibers)

[0329] The fiber diameter [μm] was measured according to EN ISO 137:2015. A nonwoven sample, or fiber sample was placed into a microscope (MESDAN Micro Lab 250E). The analysis consists of the measurement of the distance between each side of the fiber to determine the fiber diameter using the best optical degree. Generally, between 20 to 50 measures were taken to determine the mean value.

Fabric Weight

[0330] Fabric weight or mass per unit area [g/m2] was measured according to EDANA/INDA test procedure NWSP 130.1.RO (15) or ISO 9073-1:1989.

Ash Content

[0331] The ash content in [%] of the fibers and the masterbatches was determined by incineration of a sample in an incineration crucible which is put into an incineration furnace at 570° C. for 2 hours. The ash content is measured as the total amount of remaining inorganic residues.

Water Vapour Transmission Rate (WVTR)

[0332] The WVTR value of the nonwoven fabric as measured with a Lyssy L80-5000 (PBI-Dansensor A/S, Denmark) measuring device according to ASTM E398-13.

Materials

[0333] PP1: Polymer 1: Polypropylene homopolymer Borealis HG 475FB (MFR: 27 g/10 min (230° C., 2.16 kg) according to technical data sheet), commercially available from Borealis AG, Vienna, Austria.

[0334] PP2: Polymer 2: Polypropylene homopolymer Borealis HG 455FB (MFR: 27 g/10 min (230° C., 2.16 kg) according to technical data sheet), commercially available from Borealis AG, Vienna, Austria.

[0335] PP3: Polymer 3: Polypropylene homopolymer Total Polypropylene PPH 9099 (MFR: 25 g/10 min (230° C., 2.16 kg) according to technical data sheet), commercially available from Total Petrochemicals, Feluy, Belgium.

[0336] SF1: Staple fiber 1: Polypropylene staple fibers HY-Light-S (fiber length: 40 mm, titer: 3.3 dtex, according to technical data sheet), commercially available from ES Fibersvisions ApS, Varde, Denmark.

[0337] SF2: Staple fiber 2: Polyester staple fibers Max Model 140 (fiber length: 60 mm, titer: 3.3 dtex, according to technical data sheet), commercially available from Max Model SAS, Lyon, France.

[0338] SF3: Staple fiber 3: Viscose staple fibers Lenzing (fiber length: 60 mm, titer: 3.3 dtex, according to technical data sheet), commercially available from Lenzing AG, Lenzing, Austria.

[0339] CC1 (inventive): Natural ground calcium carbonate, commercially available from Omya International AG, Switzerland (d.sub.50: 1.7 μm; d.sub.98: 6 μm, content of particles <0.5 μm=12%), surface-treated with 0.7 wt. % alkenyl succinic anhydride (CAS [68784-12-3], concentration >93%), based on the total weight of the natural ground calcium carbonate. BET: 3.4 m.sup.2/g, residual moisture content: 0.1 wt.-%.

[0340] CC2 (inventive): Natural ground calcium carbonate, commercially available from Omya International AG, Switzerland (d.sub.50: 0.8 μm; d.sub.98: 3 μm, content of particles <0.5 μm=35%), surface-treated with 0.7 wt. % alkenyl succinic anhydride (CAS [68784-12-3], concentration >93%), based on the total weight of the natural ground calcium carbonate. BET: 8.5 m.sup.2/g, residual moisture content: 0.5 wt.-%.

Example 1

Preparation of Masterbatches

[0341] Polypropylene masterbatches containing the calcium carbonate fillers CC1 and CC2 and the polymer P1 were continuously prepared on a lab scale Buss kneader (Buss PR46 from Buss AG, Switzerland).

[0342] The compositions and filler contents of the prepared masterbatches are compiled in Table 1 below. The precise filler content was determined by the ash content.

TABLE-US-00001 TABLE 1 Composition and filler content of prepared masterbatches. Filler content Ash content Masterbatch Polymer Filler [wt.-%] [wt.-%] MB1 (inventive) PP1 CC1 70 68.9 MB2 (inventive) PP1 CC2 70 68.2

Example 2

Preparation of Nonwoven Fabrics (Via Spunlaid Process A with Hydro-Entanglement)

[0343] Masterbatches according to Example 1 were mixed with polymer PP2 and were directly dosed together into a single screw extruder equipped with a melt pump. Nonwoven fabrics were produced from these mixtures on a Hills spunbond pilot line, width 550 mm (Hills Inc. West Melbourne, Fla.; USA), equipped with a spin pack with 1003 holes/500 mm, 0.35 mm hole diameter. The extruder temperature was set at 235° C. with a throughput of 0.6 g/hole/min. The quenching temperature was 15° C. at 900 mm distance. The extruded filaments with 17 μm filament diameter were produced with filament speed at 2900 m/min with a fiber gap of 8 mm and 1.5 bar air pressure and formed into a nonwoven web. The filament laying distance was 400 mm and conveyor the belt speed was adjusted to receive 40 gsm nonwoven fabric weight.

[0344] The hydroentanglement process was used for bonding of the nonwoven web with an Andritz Jetlace 3000, machine width 600 mm (Andritz Perfojet SAS, Montbonnot, France). Pre-bonding was performed at 80 bar water pressure. The bonding was performed with 2 cylinders and 3 injectors (2112 strips at 2 rows with diameter 120 μm and 1.2 mm gap) in two bonding steps. Bonding step 1 was performed at cylinder 1 at a water pressure of 80 bar for injector 1 and 100 bar for injector 2. Bonding step 2 was performed at cylinder 2 at a water pressure of 100 bar for injector 1 and 80 bar for injector 2. The nonwoven fabrics were dried at 80° C. in an omega oven.

[0345] The final bonded nonwoven fabric had a target fabric weight of 40 g/m.sup.2, which was adjusted by the line speed. The compositions of the produced nonwoven materials are compiled in Table 2 below.

TABLE-US-00002 TABLE 2 Compositions of the prepared nonwoven fabrics (wt.-% is based on total weight of the sample). Masterbatch Ash content Sample [wt.-%] [wt.-%] 1 (comparative) — 0 2 (inventive) 14% MB1 9.6

Example 3

Preparation of Nonwoven Fabrics (Via Spunlaid Process B with Hydro-Entanglement)

[0346] Masterbatches according to Example 1 were mixed with polymer PP3 and were directly dosed together into a single screw extruder equipped with a melt pump. Nonwoven fabrics were produced from these mixtures on a Reicofil 4 pilot line, 1 meter width (Reifenhäuser Reicofil GmbH & Co. KG, Troisdorf, Germany), equipped with a spin pack with 7377 holes, core/sheath configuration, 0.6 mm hole diameter. Extruder temperature at 240° C. with a throughput of 0.56 g/hole/min. The quenching temperatures were at 25°/20° C. and the cabin pressure was set to 4500 Pa. The extruded filaments were formed into a nonwoven web.

[0347] The hydroentanglement process was used for bonding of the nonwoven web with a Fleissner Aquajet, machine width 600 mm (Trützschler Nonwovens GmbH, Dulmen, Germany). The bonding was performed with 2 cylinders and 3 injectors. The processing conditions for the hydro-entanglement are summarized in Table 3. The distance to belt 1 was kept at 35 mm and the distances to belt 2 and belt 3 were kept at 10 mm for all samples. The nonwoven fabrics were dried in an IR drier at 38° C. and an omega oven at 130° C.

[0348] The final bonded nonwoven fabrics had a target fabric weight of 40 g/m.sup.2, which was adjusted by the line speed. The compositions of the produced nonwoven materials are compiled in Table 3 below.

TABLE-US-00003 TABLE 3 Compositions of the prepared nonwoven fabrics (wt.-% is based on total weight of the sample) and the processing conditions for the hydro-entanglement Master- Ash Pressure Pressure Pressure batch content beam 1 beam 2 beam 3 Sample [wt.-%] [wt.-%] [bar] [bar] [bar] 6 (comparative) — 0 80 150 150 7 (inventive) 14% MB1 9.6 80 150 150 8 (comparative) 14% MB1 9.5 100 185 185

Example 4

Preparation of Multifilament Fibres

[0349] Multifilament fibres were produced by mixing of polymer PP1 and the masterbatches according to Tables 4 and 5 using a Hills multifilament pilot line (Hills Inc. West Melbourne, Fla.; USA), equipped with two single screw extruders with melt pump and spin pack (round shape bicomponent core sheath) with 74 filaments having a diameter of 0.35 mm.

TABLE-US-00004 TABLE 4 Compositions of the prepared PP multifilament fibers Sample Masterbatch [wt.-%] 4 (inventive) 14% MB 1

TABLE-US-00005 TABLE 5 Machine conditions for multifilament fiber spinning. Parameter Multifilament fibers with PP Extruder temperature 195-230° C. Adapter temperature 230° C. Spin head temperature 235° C. Godet Roll speed Roll 1: 385 m/min Roll 2: 1360 m/min Roll 3: 1370 m/min Draw ratio 2.8

[0350] The resulting multifilament fibers were converted to staple fibers with a cutting length of 40 mm using a lab pilot line in a conventional manner by unwinding, crimping, fixing the crimp in the oven and cutting them into staple fibers.

Example 5

Preparation of Nonwoven Fabrics (Via Carding Process with Hydro-Entanglement)

[0351] The bale opening and blending step was done on a Laroche Opening & Blending line (Laroche SA, Cours, France) with bale openers, horizontal opener and fine opener. The opened staple fibers were then fed into the carding line.

[0352] Carded nonwoven fabric samples were produced on an Andritz Nexline Spunlace carding pilot line (Andritz Asselin-Thibeau SAS, Elbeuf, France) equipped with main cylinder, breast roll, doffer, strippers and workers. Nonwoven samples were produced with the following settings: main cylinder at 1400 meter per minute [mpm], breast roll at 700 mpm, all other rolls between 130 and 230 mpm. The outlet speed was 22 mpm and the outlet width was 600 mm.

[0353] The hydroentanglement process was used for bonding of the nonwoven web with an Andritz Jetlace 3000, machine width 600 mm (Andritz Perfojet SAS, Montbonnot, France). Pre-bonding was performed at 70 bar water pressure. The bonding was performed with 2 cylinders and 4 injectors (2J12 strips at 2 rows with diameter 120 μm and 1.2 mm gap) with 80 bar water pressure at injector 1 and 100 bar water pressure at injector 2 on cylinder 1, 100 bar water pressure at injector 1 and 80 bar water pressure at injector 2 on cylinder 2. The nonwoven fabric was dried at 90° C. in an omega oven.

[0354] The final bonded nonwoven webs with 60 cm width had target fabric weights of 40 and 30 g/m.sup.2.

[0355] The compositions of the produced nonwoven materials are compiled in Table 6 below.

TABLE-US-00006 TABLE 6 Compositions of the prepared nonwoven fabrics (wt.-% is based on total weight of the sample). Staple fiber + Content of CC1 Fiber Targeted Sample CC1 or CC2 or CC2 [wt.-%] blends fabric weight 3 (comparative) SF1 none none 40 4 (inventive) PP1 + CC1 10% none 40 5 (comparative) SF2 + SF3 none none 40

Example 6

Tactile Properties Testing with Sensorics Panel

[0356] The tactile properties were evaluated with a sensorics panel. The purpose is to characterize the tactile properties of nonwoven fabric samples in a comparative way by means of human perception. The retained sensory methodology is an analytic quantitative approach permitting to describe and position the studied nonwoven fabrics on every pertinent tactile components generated by the panel (descriptors) in an adapted lexicon (monadic sensory profile: study one by one) based on the standard NF ISO 13299:2016.

[0357] The sensory expert tactile panel was composed of 9 experienced and trained persons. The descriptors, which were determined by the panel, are given in Table 7.

TABLE-US-00007 TABLE 7 Sensory descriptors Descriptor Rating Description Testing Method Softness  0—the least soft Overall feeling of Stroke the surface 10—the softest the touch of the of the material material with an without pressure individual and in both perceptive character. directions. Judge the pleasant aspect of the material. Downiness  0—the least downy Describes the Appose the hand 10—the most presence of fibers in flat on the surface downy the surface of the of the sample material. without pressure. Make microdeplacement of the digital pulp by small circular movements on the surface of the material, so as the fibers to roll under the fingers. Fluidity  0—the least fluid Describes the ease Seize the sample 10—the most fluid with which the by a corner and sample glides and slide the material flows between the in the hollow of finders (lack of the other hand. manipulation resistancy) Suppleness  0—the least supple Describes the ease Appose the hand 10—the most with which the flat on the surface supple sample deforms of the sample (absence of without pressure. resistance in the Slowly and deformation/folding) delicately close the hand by fixing the material with the palm to feel the material deforming.

[0358] The sensory test results were verified on statistical reliability by the mean of interferential statistic tools: ANOVA and Friedman Test.

[0359] The haptics characterization of the nonwoven samples revealed a tactile profile of the samples with large differences. These differences are statistically relevant and_unique. The results are summarized in Table 8.

TABLE-US-00008 TABLE 8 Results of the tactile properties testing. Descriptor Sample Softness Downiness Fluidity Suppleness 1 (comparative) 7.5 5.2 4.7 6.3 2 (inventive) 8.7 7.9 9.3 9.2 3 (comparative) 1.7 6.4 3.1 3.6 4 (inventive) 3.1 7.2 6.7 6.6 5 (comparative) 0.4 2.9 4.3 3.4 6 (comparative) 4.1 2.4 3.8 3.4 7 (inventive) 6.8 5.3 7.8 6.7 8 (comparative) 4.4 2.6 5.5 6.5

Example 7

Determination of Water Vapor Transmission Rate

[0360] The nonwoven fabric samples were tested on their water vapor transmission behaviour. The results are compiled in Table 9.

TABLE-US-00009 TABLE 9 Compositions of the prepared nonwoven fabrics and measured water vapor transmission rate (WVTR) values Sample WVTR [g/m.sup.2/day] 2 (inventive) Spunbond, GCC 3853 4 (inventive) Carded, GCC 4409 7 (inventive) Spunbond, GCC 4944 8 (comparative) Spunbond, GCC (higher 25 water pressure)

Clauses

[0361] The invention may be summarized in the following clauses:

[0362] Clause 1. A process for producing a nonwoven fabric, the process comprising the following steps: [0363] a) providing a surface-treated calcium carbonate-containing filler material, the surface-treated calcium carbonate-containing filler material comprising a calcium carbonate-containing filler material having prior to the surface treatment [0364] i) a weight median particle size (d.sub.50) value in the range from 0.1 μm to 7 μm, [0365] ii) a top cut (d.sub.98) value of 15 μm or less, [0366] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and [0367] iv) a residual total moisture content from 0.01 wt.-% to 1 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material, [0368] and a surface-treatment layer on at least a part of the surface of said calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 3 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material, and wherein the surface treatment agent comprises at least one carboxylic acid and/or a salt or anhydride thereof; [0369] b) providing a first polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011; [0370] c) providing a second polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011; [0371] d) forming a masterbatch by compounding the surface-treated calcium carbonate-containing filler material of step a) in an amount of 60 wt.-% to 75 wt.-%, based on the total weight of the masterbatch, with the first polypropylene polymer of step b); [0372] e) mixing the masterbatch of step d) with the second polypropylene polymer of step c) to obtain a mixture having a surface-treated calcium carbonate-containing filler material content in the range of 5 wt.-% to 15 wt.-%, based on the total weight of the mixture, [0373] f) forming the mixture of step e) into fibers having an average fiber diameter in the range from 11 to 30 μm, [0374] g) forming a fibrous web from the fibers of step f), and [0375] h) forming the non-woven fabric by hydroentanglement of the fibrous web of step g), wherein the water pressure during hydroentanglement step h) does not exceed 170 bar and wherein the final bonding step during hydroentanglement is carried out at a water pressure in the range of 80 to 170 bar.

[0376] Clause 2. The process of clause 1, wherein the nonwoven fabric has a water vapor transmission rate of at least 1000 g/(m.sup.2 day), preferably of at least 2000 g/(m.sup.2 day), and more preferably of at least 3000 g/(m.sup.2 day) measured according to ASTM E398-13.

[0377] Clause 3. The process of clause 1 or 2, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a calcium carbonate-containing filler material having prior to the surface treatment [0378] i) a weight median particle size (d.sub.50) value in the range from 0.25 μm to 5 μm, preferably from 0.5 to 4 μm, more preferably from 0.5 to 4 μm, most preferably from 1.0 to 3.5 μm, and/or [0379] ii) a top cut (d.sub.98) value of 15 μm or less, preferably of 12.5 μm or less, more preferably of 10 pm or less, most preferably of 7.5 μm or less, and/or [0380] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, preferably from 0.5 to 50 m.sup.2/g, more preferably from 0.5 to 35 m.sup.2/g, most preferably from 0.5 to 15 m.sup.2/g, as measured by the BET method, and/or [0381] iv) a residual total moisture content from 0.01 wt.-% to 0.2 wt.-%, preferably from 0.02 wt.-% to 0.15 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material.

[0382] Clause 4. The process of any of the preceding clauses, wherein the surface-treated calcium carbonate-containing filler material of step a) comprises a surface-treatment layer on at least a part of the surface of said calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 2.5 wt.-%, preferably 0.1 to 2.0 wt.-%, more preferably 0.1 to 1.0 wt.-%, and most preferably 0.2 to 0.8 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material.

[0383] Clause 5. The process of any of clauses 1 to 4, wherein the surface treatment agent comprises at least one monocarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one monocarboxylic acid and/or a salt thereof, and most preferably comprises stearic acid and/or a salt thereof.

[0384] Clause 6. The process of any of clauses 1 to 4, wherein the surface treatment agent comprises at least one dicarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one mono-substituted succinic anhydride and/or mono-substituted succinic acid and/or a salt thereof, and most preferably comprises at least one mono-substituted succinic anhydride.

[0385] Clause 7. The process of any of the preceding clauses, wherein the first polypropylene polymer of step b) and/or the second polypropylene polymer of step c) is an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 20 to 35 g/10 min, preferably 25 to 35 g/10 min, as measured according to EN ISO 1133:2011, wherein the first polypropylene polymer of step b) and the second polypropylene polymer of step c) are preferably the same polymer.

[0386] Clause 8. The process of any of the preceding clauses, wherein the masterbatch is formed in step d) by compounding the surface-treated calcium carbonate-containing filler material of step a) in an amount of 65 wt.-% to 74 wt.-%, preferably 68 wt.-% to 72 wt.-%, based on the total weight of the masterbatch, with the first polypropylene polymer of step b).

[0387] Clause 9. The process of any of the preceding clauses, wherein the fibers formed in step f) are staple fibers having [0388] an average fiber diameter in the range from 14 to 30 μm, preferably from 14 to 25 μm, or from 15 to 30 μm, and most preferably from 15 to 25 μm, and/or [0389] a titer in the range from 1 to 6 dtex, preferably 1.5 to 4 dtex, as measured by EN ISO 2062:2009 and/or [0390] a staple fiber length in the range from 30 to 90 mm, preferably 40 to 60 mm, [0391] wherein the staple fibers are preferably formed from the mixture of step e) by a process comprising the steps of multifilament or monofilament extrusion and cutting, and/or [0392] wherein the staple fibers are formed into a fibrous web during step g) preferably by carding.

[0393] Clause 10. The process of any of clauses 1 to 8, wherein the fibers formed in step f) are filaments having [0394] an average fiber diameter in the range from 14 to 30 μm, preferably from 14 to 25 μm, or from 15 to 30 μm, and most preferably from 15 to 25 μm, and/or [0395] a titer in the range from 1 to 6 dtex, preferably 1.5 to 4 dtex, as measured by EN ISO 2062:2009, [0396] wherein the filaments are preferably formed from the mixture of step e) or e2) by spunbonding and/or meltblowing.

[0397] Clause 11. The process of any of the preceding clauses, wherein in hydroentanglement step h) [0398] the pre-bonding step is performed at a water pressure of about 50 to 120 bar, preferably 60 to 110 bar, more preferably 65 to 105 bar, and/or [0399] the water pressure does not exceed 160 bar, preferably 155 bar, and/or [0400] the water pressure of the final bonding step is in the range of 90 to 160 bar, preferably 95 to 155 bar, and/or [0401] at least 95%, preferably at least 98%, more preferably at least 99% of the process water is reused, and/or [0402] the nonwoven fabric is dried after the final bonding step at a temperature below 135° C., more preferably below 120° C., even more preferably below 100° C.

[0403] Clause 12. A nonwoven fabric formed from fibers, [0404] wherein the fibers have an average fiber diameter in the range from 11 to 30 μm and are composed of a mixture comprising [0405] a first polypropylene polymer, being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011; [0406] a second polypropylene polymer being an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 15 to 40 g/10 min, as measured according to EN ISO 1133:2011, and [0407] a surface-treated calcium carbonate-containing filler material, the surface-treated calcium carbonate-containing filler material comprising a calcium carbonate-containing filler material having prior to the surface treatment [0408] i) a weight median particle size (d.sub.50) value in the range from 0.1 μm to 7 μm, [0409] ii) a top cut (d.sub.98) value of 15 μm or less, [0410] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and [0411] iv) a residual total moisture content of from 0.01 wt.-% to 1 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material, [0412] and a surface-treatment layer on at least a part of the surface of said calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 3 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material, and wherein the surface treatment agent comprises at least one carboxylic acid and/or a salt or anhydride thereof; [0413] wherein the surface-treated calcium carbonate-containing material is contained in the mixture in an amount from 5 wt.-% to 15 wt.-%, based on the total weight of the mixture, and wherein the nonwoven fabric has a water vapor transmission rate of at least 1000 g/(m.sup.2 day), measured according to ASTM E398-13.

[0414] Clause 13. The nonwoven fabric of clause 12, wherein the nonwoven fabric has a water vapor transmission rate of at least 2000 g/(m.sup.2 day), and preferably of at least 3000 g/(m.sup.2 day), measured according to ASTM E398-13.

[0415] Clause 14. The nonwoven fabric of clause 12 or 13, wherein the surface-treated calcium carbonate-containing filler material comprises a calcium carbonate-containing filler material having prior to the surface treatment [0416] i) a weight median particle size (d.sub.50) value in the range from 0.25 μm to 5 μm, preferably from 0.5 to 4 μm, more preferably from 0.5 to 4 μm, most preferably from 1.0 to 3.5 μm, and/or [0417] ii) a top cut (d.sub.98) value of 15 μm or less, preferably of 12.5 μm or less, more preferably of 10 μm or less, most preferably of 7.5 μm or less, and/or [0418] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, preferably from 0.5 to 50 m.sup.2/g, more preferably from 0.5 to 35 m.sup.2/g, most preferably from 0.5 to 15 m.sup.2/g, as measured by the BET method, and/or [0419] iv) a residual total moisture content from 0.01 wt.-% to 0.2 wt.-%, preferably from 0.02 wt.-% to 0.15 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material.

[0420] Clause 15. The nonwoven fabric of any of clauses 12 to 14, wherein the surface-treated calcium carbonate-containing filler material comprises a surface-treatment layer on at least a part of the surface of said calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 2.5 wt.-%, preferably 0.1 to 2.0 wt.-%, more preferably 0.1 to 1.0 wt.-%, and most preferably 0.2 to 0.8 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material.

[0421] Clause 16. The nonwoven fabric of any of clauses 12 to 15, wherein the surface treatment agent comprises at least one monocarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one monocarboxylic acid and/or a salt thereof, and most preferably comprises stearic acid and/or a salt thereof.

[0422] Clause 17. The nonwoven fabric of any of clauses 12 to 15, wherein the surface treatment agent comprises at least one dicarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one mono-substituted succinic anhydride and/or mono-substituted succinic acid and/or a salt thereof, and most preferably comprises at least one mono-substituted succinic anhydride.

[0423] Clause 18. The nonwoven fabric of any of clauses 12 to 17, wherein the first polypropylene polymer and/or the second polypropylene polymer is an isotactic polypropylene homopolymer having a melt flow rate MFR (230° C./2.16 kg) in the range of 20 to 35 g/10 min, preferably 25 to 35 g/10 min, as measured according to EN ISO 1133:2011, wherein the first polypropylene polymer and the second polypropylene polymer are preferably the same polymer.

[0424] Clause 19. The nonwoven fabric of any of clauses 12 to 18, wherein the fibers are staple fibers having [0425] an average fiber diameter in the range from 14 to 30 μm, preferably from 14 to 25 μm, or from 15 to 30 μm, and most preferably from 15 to 25 μm, and/or [0426] a titer in the range from 1 to 6 dtex, preferably 1.5 to 4 dtex, as measured by EN ISO 2062:2009 and/or [0427] a staple fiber length in the range from 30 to 90 mm preferably 40 to 60 mm, [0428] wherein the staple fibers are preferably formed from the mixture of step e) by a process comprising the steps of multifilament or monofilament extrusion and cutting, and/or [0429] wherein the staple fibers are formed into a fibrous web during step g) preferably by carding.

[0430] Clause 20. The nonwoven fabric of any of clauses 12 to 18, wherein the fibers are filaments having [0431] an average fiber diameter in the range from 14 to 30 μm, preferably from 14 to 25 μm, or from 15 to 30 μm, and most preferably from 15 to 25 μm, and/or [0432] a titer in the range from 1 to 6 dtex, preferably 1.5 to 4 dtex, as measured by EN ISO 2062:2009, [0433] wherein the filaments are preferably formed from the mixture of step e) or e2) by spunbonding and/or meltblowing.

[0434] Clause 21. Use of a surface-treated calcium carbonate-containing filler material for the manufacture of a nonwoven fabric having a water vapor transmission rate of at least 1000 g/(m.sup.2 day), measured according to ASTM E398-13, preferably of at least 2000 g/(m.sup.2 day), and more preferably of at least 3000 g/(m.sup.2 day), wherein the surface-treated calcium carbonate-containing filler material comprises a calcium carbonate-containing filler material having prior to the surface treatment [0435] i) a weight median particle size (d.sub.50) value in the range from 0.1 μm to 7 μm, [0436] ii) a top cut (d.sub.98) value of 15 μm or less, [0437] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, as measured by the BET method, and [0438] iv) a residual total moisture content of from 0.01 wt.-% to 1 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material, and a surface-treatment layer on at least a part of the surface of said calcium [0439] carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 3 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material, and wherein the surface treatment agent comprises at least one carboxylic acid and/or a salt or anhydride thereof.

[0440] Clause 22. The use of clause 21, wherein the surface-treated calcium carbonate-containing filler material comprises a calcium carbonate-containing filler material having prior to the surface treatment [0441] i) a weight median particle size (d.sub.50) value in the range from 0.25 μm to 5 μm, preferably from 0.5 to 4 μm, more preferably from 0.5 to 4 μm, most preferably from 1.0 to 3.5 μm, and/or [0442] ii) a top cut (d.sub.98) value of 15 μm or less, preferably of 12.5 μm or less, more preferably of 10 pm or less, most preferably of 7.5 μm or less, and/or [0443] iii) a specific surface area (BET) from 0.5 to 120 m.sup.2/g, preferably from 0.5 to 50 m.sup.2/g, more preferably from 0.5 to 35 m.sup.2/g, most preferably from 0.5 to 15 m.sup.2/g, as measured by the BET method, and/or [0444] iv) a residual total moisture content from 0.01 wt.-% to 0.2 wt.-%, preferably from 0.02 wt.-% to 0.15 wt.-%, based on the total dry weight of the at least one calcium carbonate-containing filler material.

[0445] Clause 23. The use of any of clauses 21 or 22, wherein the surface-treated calcium carbonate-containing filler material comprises a surface-treatment layer on at least a part of the surface of said calcium carbonate-containing filler material, wherein the surface-treatment layer is formed by contacting the calcium carbonate-containing filler material with a surface treatment agent in an amount from 0.1 to 2.5 wt.-%, preferably 0.1 to 2.0 wt.-%, more preferably 0.1 to 1.0 wt.-%, and most preferably 0.2 to 0.8 wt.-%, based on the total dry weight of the calcium carbonate-containing filler material.

[0446] Clause 24. The use of any of clauses 21 to 23, wherein the surface treatment agent comprises at least one monocarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one monocarboxylic acid and/or a salt thereof, and most preferably comprises stearic acid and/or a salt thereof.

[0447] Clause 25. The use of any of clauses 21 to 23, wherein the surface treatment agent comprises at least one dicarboxylic acid and/or a salt or anhydride thereof, preferably comprises at least one mono-substituted succinic anhydride and/or mono-substituted succinic acid and/or a salt thereof, and most preferably comprises at least one mono-substituted succinic anhydride.

[0448] Clause 26. An article comprising the nonwoven fabric of clauses 12 to 20 and/or the nonwoven fabric as obtained in the process according to any of clauses 1 to 11.