High barrier nonwoven fabric

Abstract

The invention relates to a method for making a nonwoven fabric comprising forming polymer fibers from a melt of the polymer material and using these fibers to obtain a nonwoven fabric during a subsequent nonwoven fabric formation procedure, wherein the melt of the polymer material comprises a melt additive, wherein the method comprises thermal bonding at a temperature higher than 40° C. below the melting point of the polymer material and, additionally, one or both of the following steps: a. improving the mobility of the additive by heat-treating the nonwoven fabric at 100° C. or more for 0.1 seconds or more after the nonwoven fabric formation procedure and/or including a filler having a higher thermal conductivity than the polymer material to the polymer material; b. influencing the polymer crystallinity by including a nucleating agent, branched polymers and/or random co-polymers to the polymer material.

Claims

1. A method for making a nonwoven fabric comprising: forming polymer fibers from a melt of the polymer material and using these fibers to obtain a nonwoven fabric during a subsequent nonwoven fabric formation procedure, wherein the polymer material comprises a thermoplastic polyolefin and wherein the melt of the polymer material comprises a melt additive which comprises a fatty acid ester derived from C.sub.8-25 unsaturated or saturated carboxylic acids, thermal bonding at a temperature higher than 40° C. below the melting point of the polymer material and, additionally, one or both of the following steps: a. improving the mobility of the additive by including a filler having a higher thermal conductivity than the polymer material to the polymer material; and b. influencing the polymer crystallinity by including a nucleating agent, branched polymers and/or random co-polymers to the polymer material.

2. The method of claim 1, wherein the polymer material consists of or comprises a thermoplastic polymer.

3. The method of claim 1, wherein the filler has a thermal conductivity that is higher than the thermal conductivity of the polymer material by at least 0.2 W.Math.m.sup.−1.Math.K.sup.−1.

4. The method of claim 1, wherein the average particle size of the filler is 10 μm or smaller or wherein its thermal conductivity at room temperature is 1 W.Math.m.sup.−1.Math.K.sup.−1.

5. The method of claim 1, wherein the filler comprises CaCO.sub.3 and preferably ground or precipitated CaCO.sub.3.

6. The method of claim 1, wherein the nucleating agent comprises a nonitol, a trisamide, a sorbitol-based nucleating agent and/or an inorganic particulate having a particle size of 10 μm.

7. The method of claim 1, further comprising forming multicomponent polymer fibers from the melt of the one polymer material and a melt of another polymer material, wherein the other polymer material includes less or no additive, wherein at least the majority of the fiber surface is covered by the one polymer material and wherein thermal bonding is carried out at a temperature higher than 40° C. below the melting point of the lower melting polymer material.

8. The method of claim 7, wherein the multicomponent fiber is a bicomponent fiber or is of core-sheath configuration with the component going back to the one polymer material accounting for the sheath.

9. The method of claim 8, wherein the one and the other polymer material both are made of or comprise a thermoplastic polymer.

10. The method of claim 1, wherein the method comprises a continuous process for making a nonwoven fabric, where the fibers are continuously spun and directly dispersed on a carrier belt.

11. The method of claim 1, wherein the additive comprises a fatty acid ester derived from C.sub.8-25, C.sub.10-20 or C.sub.14-18 unsaturated or saturated carboxylic acids.

12. A nonwoven fabric obtainable by the process of: forming polymer fibers from a melt of the polymer material and using these fibers to obtain a nonwoven fabric during a subsequent nonwoven fabric formation procedure, wherein the polymer material comprises a thermoplastic polyolefin and wherein the melt of the polymer material comprises a melt additive which comprises a fatty acid ester derived from C.sub.8-25 unsaturated or saturated carboxylic acids, thermal bonding at a temperature higher than 40° C. below the melting point of the polymer material and, additionally, one or both of the following steps: improving the mobility of the additive by heat-treating the nonwoven fabric at 100° C. or more for 0.1 seconds or more after the nonwoven fabric formation procedure and/or including a filler having a higher thermal conductivity than the polymer material to the polymer material; influencing the polymer crystallinity by including a nucleating agent, branched polymers and/or random co-polymers to the polymer material, the fabric comprising polymer fibers where the melt additive is included in the polymer matrix, where the concentration of the melt additive is higher in a surface region than in a core region of the fibers and wherein the fibers comprise a rugged surface topography.

13. The method of claim 1, wherein the polymer material consists of or comprises of a polyolefin of at least one of polypropylene, polyethylene and Ethylene-Propylene copolymer or a combination of these.

14. The method of claim 1, wherein the average particle size of the filler is 1 μm or smaller and its thermal conductivity at room temperature is 2.0 W.Math.m.sup.−1.Math.K.sup.−1 or more.

15. The method of claim 1, wherein the nucleating agent comprises a nonitol, a trisamide, a sorbitol-based nucleating agent or an inorganic particulate having a particle size of 1 μm or smaller.

16. The method of claim 8, wherein the one and the other polymer material both are made of or comprise of at least one of a polyolefin, polyethylene and Ethylene-Propylene copolymer or a combination of these.

17. The method of claim 1, wherein the method comprises making a spunbonded or meltblown nonwoven fabric.

18. The method of claim 1, wherein the additive comprises a triglyceride.

19. A method for making a nonwoven fabric comprising: forming polymer fibers from a melt of the polymer material and using these fibers to form a nonwoven fabric, wherein the polymer material comprises a thermoplastic polyolefin, and wherein the melt of the polymer material comprises a melt additive which comprises a fatty acid ester derived from C.sub.8-25 unsaturated or saturated carboxylic acids, thermal bonding at a temperature higher than 40° C. below the melting point of the polymer material; heat-treating the nonwoven fabric at 100° C. or more for 0.1 seconds or more after forming the nonwoven fabric to improve the mobility of the additive; adding a filler having a higher thermal conductivity than the polymer material to the polymer material; and adding a nucleating agent, branched polymers or random co-polymers to the polymer material to influence the polymer crystallinity.

20. The method of claim 1, further comprising heat-treating the nonwoven fabric in an additional step after the thermal bonding.

Description

EXAMPLES 1-4

(1) Spunbonded (S) single layer nonwoven fabrics were produced from 100-x wt % Ziegler-Natta polypropylene and x wt % of a hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layers had a weight of 20 g/m2. The contents of the hydrophobic additive in Examples 1-4 are summarized in Table 1.

(2) TABLE-US-00001 TABLE 1 Example X [wt %] 1 0 2 3 3 6 4 10

(3) Examples 1-4 were tested for Low Surface Tension Strike Through (LST-ST). The results are summarized in Table 2.

(4) TABLE-US-00002 TABLE 2 LST-ST Example 1 2 3 4 5.20 14.13 8.25 10.22 5.12 7.04 12.45 16.70 4.27 6.97 11.93 9.84 4.15 8.20 11.64 19.81 4.80 7.41 14.13 12.64 4.95 7.54 9.87 13.26 3.80 7.53 10.16 11.41 4.30 7.16 13.05 9.39 4.66 8.68 9.25 20.75 4.30 7.37 12.17 8.80 5.08 6.98 10.32 10.40 6.11 7.24 10.16 16.93 4.74 7.89 11.65 14.83 5.21 9.47 11.72 12.56 6.25 8.58 11.19 16.33 Average 4.86 8.15 11.20 13.59 Std. Dev 0.68 1.81 1.53 3.81 Min 3.80 6.97 8.25 8.80 Max 6.25 14.13 14.13 20.75

EXAMPLE 5-7

(5) Three S single layer nonwovens were produced from 100% Ziegler-Natta polypropylene and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwovens they were thermally treated with an in-line Omega Drying oven at 90° C., 120° C. and 135° C., for Example 5, 6 and 7, respectively.

EXAMPLE 8

(6) An S single layer nonwoven was produced from 100% Ziegler-Natta polypropylene and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process the nonwoven was thermally treated with an in-line IR-heater set to 65% power at the center and 60% at the edge of the nonwoven web.

EXAMPLE 9

(7) An S single layer nonwoven was produced from 100% Ziegler-Natta polypropylene and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process the nonwoven was thermally treated with an in-line Omega Drying oven at 120° C. Opposite Example 6, the through put had been decreased in the production of the material, resulting in a decreased line speed to increase the duration of the heat treatment. The resulting heat treatment of Example 9 was 15% longer than that of Example 6.

(8) Table 3 below shows the resulting LST-ST measured on Example 5-9.

(9) TABLE-US-00003 TABLE 3 Example 5 6 7 8 9 6.93 8.15 8.41 5.73 6.45 6.98 6.56 9.00 7.45 8.82 7.36 6.97 7.21 6.57 7.59 5.88 7.30 6.63 8.21 8.31 6.30 7.54 6.01 6.84 7.40 7.57 7.39 6.41 6.62 10.42 3.27 5.95 7.18 8.17 8.14 6.30 6.31 6.83 6.46 6.99 6.15 6.99 6.56 6.23 5.97 5.96 8.25 6.03 6.60 7.97 Average 6.27 7.14 7.03 6.89 7.81 Std. Dev 1.21 0.74 0.98 0.81 1.26 Min 3.27 5.95 6.01 5.73 5.97 Max 7.57 8.25 9.00 8.21 10.42

EXAMPLES 10-13

(10) Four S single layer nonwovens were produced from 90 wt % Ziegler-Natta polypropylene and 10 wt % of a hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwovens they were thermally treated with an in-line Omega Drying oven set to 90° C., 105° C., 120° C. and 135° C. for Example 10, 11, 12 and 13, respectively.

EXAMPLES 14-17

(11) Four S single layer nonwovens were produced from 90 wt % Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwovens they were thermally treated with an in-line IR-heater set to 50% power at the center and 45% at the edge of the nonwoven web, 60% power at the center and 55% at the edge of the nonwoven web, 65% power at the center and 50% at the edge of the nonwoven web, and 70% power at the center and 65% at the edge of the nonwoven web for Example 14, 15, 16 and 17, respectively.

EXAMPLE 18

(12) An S single layer nonwoven was produced from 90 wt % Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwoven it was thermally treated with an in-line IR-heater set to 65% power at the center and 60% at the edge of the nonwoven web, followed by heating in an Omega Drying oven at 120° C.

(13) The hydrophobic additive content and heat treatment for Examples 10-18 are summarized in Table 4 below.

(14) TABLE-US-00004 TABLE 4 Configuration S 20 g/m2 PPM17000 in S IR heater, Omega Drying oven Example [%] center/edge [%] temperature [° C.] 10 10 N/A  90 11 10 N/A 105 12 10 N/A 120 13 10 N/A 135 14 10 50/45 N/A 15 10 60/55 N/A 16 10 65/60 N/A 17 10 70/65 N/A 18 10 65/60 120

(15) LST-ST was measured on Example 10-18. The results are shown in Table 7.

(16) TABLE-US-00005 TABLE 5 Example 10 11 12 13 14 15 16 17 18 76.00 101.24 234.77 395.48 15.26 14.84 104.54 98.37 215.35 61.97 49.95 276.72 657.52 17.00 12.71 152.30 111.38 110.34 46.90 112.09 146.37 430.89 20.50 14.10 112.22 110.01 198.74 74.91 88.00 273.29 474.56 19.56 28.91 266.32 98.23 410.14 42.44 109.78 58.76 198.51 15.18 18.06 95.32 126.05 217.10 79.87 142.88 305.67 494.47 22.90 19.65 156.70 55.01 38.29 40.85 140.77 538.19 11.38 15.53 304.52 64.02 67.46 37.91 196.46 380.06 18.17 20.92 138.70 113.62 35.59 93.40 51.80 609.90 24.31 25.86 301.90 70.28 65.22 213.77 178.43 437.63 19.12 16.57 211.70 74.74 20.24 16.76 270.70 52.05 16.97 19.58 317.12 86.01 36.15 30.45 216.29 33.97 12.96 30.45 273.13 76.24 19.00 14.05 408.33 96.01 Average 58.87 98.99 186.30 461.72 19.25 19.90 221.99 84.40 230.33 Std. Dev 16.65 52.77 88.53 128.77 5.81 6.15 93.35 26.36 109.69 Min 35.59 37.91 51.80 198.51 11.38 12.71 95.32 33.97 110.34 Max 79.87 213.77 305.67 657.52 36.15 30.45 408.33 126.05 410.14

EXAMPLE 19

(17) An S single layer nonwoven was produced from 90 wt % Ziegler-Natta polypropylene and 10 wt % hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layer had a weight of 20 g/m2. Compared to Example 4, the temperature of the calender thermally bonding the nonwoven was increased with +10° C.

(18) Table 6 below shows the LST-ST results from Example 19.

(19) TABLE-US-00006 TABLE 6 LST ST [s] Example 19 19.34 14.72 20.11 14.50 60.64 15.93 27.21 18.45 32.66 46.12 36.68 16.23 17.71 26.82 41.66 Average 27.25 Std. dev. 13.75 Min 14.50 Max 60.64

(20) It can be see that when increasing the calender temperature with 10° C., the LST ST increases from 13.59 seconds (4) to 27.25 seconds (19).

EXAMPLE 20

(21) An S single layer nonwoven was produced from 90% Ziegler-Natta polypropylene and 10 wt % of a hydrophobic melt additive (PPM17000 High Load Hydrophobic) and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process the nonwoven was thermally treated with an in-line Omega Drying oven at 120° C. As Example 13, the through put had been decreased in the production of the material, resulting in a decreased line speed to increase the duration of the in-line heat treatment. The resulting heat treatment of Example 20 was 15% longer than that of Example 12 and comparable to the heat treatment of Example 6.

(22) Table 7 below shows the LST-ST results from Example 20.

(23) TABLE-US-00007 TABLE 7 LST ST [s] Example 20 254.16 342.97 386.78 134.31 656.06 Average 354.86 Std. dev. 194.08 Min 134.31 Max 656.06

(24) It can be seen that when increasing the heat treatment time with 15%, it increases the performance in terms of LST ST from 186.30 seconds (12) to 354.86 seconds (20).

EXAMPLE 21

(25) A Spunbond single layer fabric was produced with bicomponent core/sheath configuration, consisting of 70 wt % core and 30 wt % sheath. The core comprised 100% Ziegler-Natta polypropylene. The sheath comprised 67 wt % Ziegler-Natta polypropylene and 33 wt % hydrophobic melt additive (PPM17000 High Load Hydrophobic). The nonwoven was thermally bonded. The single S-layer had a weight of 20 g/m2.

EXAMPLE 22-24

(26) Spunbond single layer fabrics were produced with bicomponent core/sheath configuration, consisting of 70 wt % core and 30 wt %. The core comprised 100 wt % Ziegler-Natta polypropylene. The sheath comprised 100-X wt % Ziegler-Natta polypropylene and X wt % hydrophobic melt additive (PPM17000 High Load Hydrophobic). The nonwoven was thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwovens they were thermally treated by an in-line IR-heater set to 65% power at the center and 50% at the edge of the nonwoven web.

(27) The contents of the hydrophobic additive in the sheath of the fiber in Examples 22-24 are summarized in below Table 8.

(28) TABLE-US-00008 TABLE 8 Example X [wt %] 22 10 23 20 24 33

(29) Table 9 below shows LST-ST results on Examples 21-24.

(30) TABLE-US-00009 TABLE 9 Example 21 22 23 24 28.11 14.3 82.41 240.61 17.14 13.56 43.19 273.30 36.59 16.44 62.41 153.60 12.35 15.81 72.28 147.92 22.51 11.42 73.37 146.09 41.57 10.70 117.86 502.41 19.49 12.32 62.87 483.81 25.87 12.74 110.75 262.96 40.68 20.02 89.87 262.52 30.65 14.95 91.99 370.45 50.5 12.17 68.66 303.56 10.03 16.71 51.44 249.07 39.32 15.62 58.81 250.07 20.28 13.28 94.30 354.30 31.93 11.71 91.45 150.39 Average 28.47 14.12 78.11 276.74 Std. Dev 11.73 2.50 21.32 112.54 Min 10.03 10.70 43.19 146.09 Max 50.50 20.02 117.86 502.41

EXAMPLE 25

(31) A spunbond single layer fabric was produced with bicomponent core/sheath configuration, consisting of 70 wt % core and 30 wt %. The core comprised 100 wt % Ziegler-Natta polypropylene. The sheath comprised 67 wt % propylene-based elastomer (consisting of approx. 15 wt % ethylene) and 33 wt % of a hydrophobic melt additive (PPM17000 High Load Hydrophobic). The nonwoven was thermally bonded. The single S-layer had a weight of 20 g/m2.

(32) Table 10 below shows the LST-ST results on Example 25:

(33) TABLE-US-00010 TABLE 10 Example 25 136.81 77.96 134.97 74.01 118.13 57.90 38.32 132.20 138.89 94.23 Average 100.34 Std. Dev 36.86 Min 38.32 Max 138.89

(34) Example 21 to Example 25 reveals an increase in LST-ST from 28.47 seconds to 100.34 seconds when substituting Ziegler-Natta polypropylene in the sheath of the bicomponent fiber with a propylene-based elastomer in the sheath of the bicomponent fiber.

EXAMPLE 26

(35) A spunbond single layer fabric was produced was produced from 80 wt % Ziegler-Natta polypropylene, 10 wt % of a hydrophobic melt additive (PPM17000 High Load Hydrophobic), and 10 wt % of a Calcium Carbonate masterbatch (Fiberlink 201S). The fabric was thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwoven it was thermally treated by an in-line IR-heater set to 65% power at the center and 60% at the edge of the nonwoven web followed by in-line heating in an Omega Drying oven at 120° C.

EXAMPLE 27

(36) A spunbond single layer fabric was produced was produced from 90 wt % Ziegler-Natta polypropylene, and 10 wt % of Calcium Carbonate masterbatch (Fiberlink 201S) and thermally bonded. The single S-layer had a weight of 20 g/m2. After the web making process of the nonwoven it was thermally treated in an in-line Omega Drying oven at 120° C.

(37) An overview of Example 26 and 27 is provided in Table 11 below.

(38) TABLE-US-00011 TABLE 11 Configuration S 20 g/m2 Omega PPM17000 Fiberlink Drying oven IR heater, Example in S [%] 201S [%] temperature [° C.] center/edge [%] 26 10 10 120 65/60 27 0 10 120 N/A

(39) LST-ST results on Examples 26 and 27 are illustrated in Table 12 below.

(40) TABLE-US-00012 TABLE 12 LST-ST [s] Example 26 27 604.02 4.93 530.34 5.93 898.10 5.55 685.93 5.63 838.60 6.84 522.90 4.55 5.45 5.33 5.21 5.69 Average 679.98 5.51 Std. dev. 158.50 0.61 Min 522.90 4.55 Max 898.10 6.84

(41) The LST-ST results reveal a LST ST of 5.51 seconds for Example 27, which shows that the presence of CaCO3 alone does not increase the LST-ST performance. The LST-ST of Example 26 compared to Example 18, reveals that the presence of CaCO3 and the applied heat treatments of the IR-heater and Omega Drying oven increases the LST ST from 230.33 seconds to 679.98 seconds. When comparing the state of the art of Example 4 to Example 26, the performance increases from 13.59 seconds to 679.98 seconds.

EXAMPLES 28-29

(42) Two SMMS-multilayered nonwoven fabrics were produced from Ziegler-Natta polypropylene. The fabrics we added a hydrophobic additive (PPM17000 High Load Hydrophobic) to the various layers as described in Table 13. After the web making process of Example 29 the fabric was added a heat treatment with an in-line Omega Drying oven.

(43) Table 13 gives an overview on material layup, additive content and heat treatment.

(44) TABLE-US-00013 TABLE 13 Lay-up [g] Configuration S M M S SMMS 5.5 1 1 5.5 13 Omega Drying Total oven temperature Example PPM17000 per beam [%] PPM17000 [%] [° C.] 28 0 6 6 6 3.5 N/A 29 0 6 6 6 3.5 120

(45) Examples 28-29 were tested for Low Surface Tension Strike Through (LST-ST). The results are summarized in Table 14.

(46) TABLE-US-00014 TABLE 14 LST-ST [s] Example 28 29 18.35 23.99 22.44 25.67 21.70 28.36 16.52 28.99 23.13 30.71 21.09 36.43 24.01 33.29 22.42 35.08 21.30 30.98 30.27 30.78 28.86 31.71 30.13 31.09 17.95 29.27 25.50 34.52 28.48 31.24 19.34 24.87 25.11 32.50 20.44 37.55 27.07 34.13 26.68 30.61 27.65 33.90 30.11 40.04 17.50 32.49 36.19 26.82 30.73 27.60 Average 24.52 31.30 Std. dev. 5.03 4.70 Min 16.52 40.60 Max 36.19 59.50

EXAMPLES 30-32

(47) Three SS materials were produced with the spunbond fibers in both layers being bicomponent fibers of core/sheath configuration with a polyethylene sheath, accounting for 30 wt % of the total fiber, and polypropylene core, accounting for 70 wt % of the total fiber. A hydrophobic additive (PM16310) was added in 17% to the bicomponent's PE sheath of both of S layers for Examples 30-32. After the web making process of Example 31-32 the fabrics were added a heat treatment with an in-line Omega Drying oven of 100° C. and 120° C. for Example 31 and Example 32, respectively.

(48) Table 15 gives an overview on material layup, additive content and heat treatment.

(49) TABLE-US-00015 TABLE 15 Lay-up [g] S S Core Sheath Core Sheath Configuration (PP) (PE) (PP) (PE) SS 8.75 3.75 8.75 3.75 25 Total Omega Ex- PPM17000 in PPM17000 Drying oven ample sheath per beam [%] [%] temperature [° C.] 30 17 17 5.1 N/A 31 17 17 5.1 100 32 17 17 5.1 120

(50) Examples 30-32 were tested for Low Surface Tension Strike Through (LST-ST). The results are summarized in Table 16.

(51) TABLE-US-00016 TABLE 16 LST-ST [s] Example 30 31 32 21.19 16.97 16.97 33.40 22.91 22.91 12.02 18.31 18.31 22.27 22.74 22.74 12.20 22.07 22.07 24.97 28.60 37.35 23.32 15.60 20.47 26.33 44.03 33.25 24.18 26.22 33.32 16.26 20.00 37.67 26.33 23.13 37.84 20.08 29.65 29.83 41.91 20.15 24.42 47.98 20.91 43.57 15.03 17.98 26.59 13.90 17.99 42.61 34.62 17.22 27.74 25.18 12.88 22.61 12.25 16.47 30.74 32.08 18.53 35.16 34.70 26.60 31.49 13.69 21.61 43.26 45.44 34.48 54.21 21.81 14.35 35.09 36.77 32.79 40.69 Average 25.52 22.49 31.64 Min 12.02 12.88 16.97 Max 47.98 44.03 54.21 Std. dev. 10.31 7.00 9.10