RU2811530C2 - Method for producing nonwoven fabric from spunbond nonwoven material with high elasticity - Google Patents

Abstract

FIELD: fabric manufacturing.

SUBSTANCE: present invention is related to a method for producing a nonwoven fabric from a spunbond nonwoven material with high elasticity containing crimped multicomponent fibres, the method includes continuous spinning of the fibres, directing the fibres onto the spinning conveyor by means of deflectors and/or air flows, laying out the fibres on the spinning conveyor and preliminary consolidation of the fibres after lay-up using one or more pre-consolidation rolls to form a pre-consolidated mesh, wherein the first fibre component comprises a PP homopolymer and the second fibre component comprises a PP/PE copolymer, wherein the pre-consolidation rolls operate at temperatures below 110°C and/or with a linear contact force less than 5 N/mm.

EFFECT: method for producing nonwoven fabric is proposed.

18 cl, 10 tbl, 4 dwg

Description

The present invention relates to a method for producing a spunbond nonwoven fabric with high elasticity containing crimped multicomponent fibers. In addition, the present invention relates to non-woven fabrics obtained using such a method.

Spunbonded nonwoven layers with high resiliency can contribute to nonwovens having high softness, as desired for personal care products such as diapers, sanitary napkins, and the like. Nonwovens containing layers of high-resilience spunbonded nonwoven based on crimped fibers are known in the art.

One of the high-resilience spunbonded nonwovens is described in US Pat. No. 6,454,989 B1. The crimp of the fibers is achieved when using multicomponent fibers, where the two components have different melt flow rates. Another spunbond nonwoven material with high elasticity is described in EP 2 343 406 B1. Fiber crimp is achieved when using multicomponent fibers, where the two components have similar melt flow rates and melting temperatures, but a certain difference in terms of Z-average and weight average molecular weight distributions. Another spunbond nonwoven fabric with high elasticity is described in EP 1 369 518 B1. The crimp of the fibers is achieved by using multicomponent fibers, where one of the components is a homopolymer and the other component is a copolymer.

None of the nonwoven materials known from the literature is completely satisfactory in terms of elasticity, softness and tensile properties. The aim of the present invention is to provide a method for producing spunbonded nonwoven materials with high elasticity, which are more satisfactory in terms of these properties.

Against the background of the prior art, the present invention relates to a method for producing a nonwoven fabric from a spunbond nonwoven material with high elasticity containing crimped multicomponent fibers, the method includes continuous spinning of the fibers, directing the fibers onto the spinning conveyor by means of baffles and/or air flows, laying out the fibers on the spinning conveyor and pre-consolidating the fibers after lay-up using one or more pre-consolidating rolls to form a pre-consolidating web, wherein the first fiber component comprises a PP homopolymer and the second fiber component comprises a PP/PE copolymer, and wherein the pre-consolidating rolls are operated at a temperature below 110 °C and/or with a linear contact force less than 5 N/mm.

Both PP homopolymer and PP/PE copolymer are thermoplastic. In one embodiment, the PP homopolymer and the PP/PE copolymer, respectively, are the only polymers contained in the first and second component, respectively. The first and second components, respectively, may consist of a PP homopolymer and a PP/PE copolymer, respectively, and optionally non-polymer additives.

In one embodiment, the PP homopolymer and/or the PP component of the PP/PE copolymer may contain a mixture of several PP-based polymers.

The fibers are preferably helically crimped and/or continuous fibers.

The fabric produced by the method of the present invention, while having a very soft feel, similar to microfleece fabric, has high tensile properties. The addition of PE/PP copolymer is said to eliminate the unwanted dry or cottony feel.

In one embodiment, the preconsolidation rolls are operated at a temperature of 50-100°C, preferably 60-80°C and/or a linear contact force of 1-4 N/mm, preferably 2-3 N/mm. A linear contact force of 1-2.5 N/mm may also be preferred. Temperatures of 20-<110°C, 40-90°C or 55-75°C may also be preferred.

In one embodiment, the content of ethylene-derived repeating units in the PP/PE copolymer is 1-10% by weight, preferably 2-6% by weight, and more preferably 3-5% by weight. A content of >0-5% by weight may also be preferred.

In one embodiment, the PP/PE copolymer is a random copolymer.

In one embodiment, the PP homopolymer is isotactic.

In one embodiment, the melt flow rates and/or polydispersities of the PP homopolymer and the PP/PE copolymer differ by less than 30%, less than 25%, or less than 20%. In terms of absolute MFR (melt flow rate) values, the PP homopolymer and/or PP/PE copolymer may be in the range of 20 to 40 or 25 to 35, for example at about 25, 30 or 35 g/10 min.

In one embodiment, the melting temperatures (TM) of the PP homopolymer and the PP/PE copolymer differ by 5°C or 10°C or more and/or they differ by 20°C or less. The difference in TM (melting temperatures) can be within 5-20°C. In terms of absolute values, for example, a PP homopolymer may exhibit a melting point in the range of 155-165°C or 159-163°C, and a PP/PE copolymer may exhibit a melting temperature in the range of 140-148°C or 142-146°C . Melting points can be determined using DSC (differential scanning calorimetry).

In one embodiment, the fibers have a density of 1.2-3.0 denier.

In one embodiment, the multicomponent fibers are bicomponent fibers.

In one embodiment, the multicomponent fibers are in a side-by-side configuration. In an alternative embodiment, the multicomponent fibers may have an (eccentric) sheath-core configuration or a trilobed configuration.

In one embodiment, the weight ratio of the first and second component in the multicomponent fibers is 40/60-80/20, preferably 40/60-60/40.

In one embodiment, the method further includes binding the pre-consolidated web using one or more calendering rolls, at least one of which is grooved. In one embodiment, the structure of the bonds that are introduced using the calendering rolls contains a bond area of 10-16% and/or a point density of 20-45 points/cm ² and/or a point size of 0.35-0.55 mm ² per one point to leave enough space for as many of the crimped fibers as possible to protrude from the structure. In one embodiment, the calendering rolls operate at a temperature of from 120 to 145°C.

In one embodiment, the method further includes binding the pre-consolidated web using hot air through-blown binding. In one embodiment, the air used when associated with the hot air through-purge has a temperature of 120 to 145°C.

In one embodiment, the method uses a hybrid process wherein the preconsolidated tissue is further activated or bonded in a final bonding process using at least two bonding technologies consisting of thermal roll bonding, IR bonding, and hot through-blown bonding. air combined.

In one embodiment, the method of the present invention forms part of a general method for forming a laminated nonwoven fabric, such as, for example, a spunmelt nonwoven fabric of the SMS, S _H S _S S _H , S _S S _H , or other type.

The general process may include additional methods of the present invention for forming layers of spunbonded nonwoven material with high resiliency, wherein each layer is preconsolidated using preconsolidation rolls operating at a described temperature and/or a described linear contact force. In one embodiment of such a general method, bonding can only occur after all layers have been laid out and pre-consolidated.

In one embodiment, the overall process includes the use of at least one layer of meltblown material (M) and/or at least one layer of spunbonded nonwoven material with standard elasticity (S _S ), where these the additional layers form a nonwoven laminate with at least one layer of spunbonded high resiliency ( _SH ) nonwoven fabric produced by the process of the present invention, preferably an SMS type, S _H S _S S _H type, or S type nonwoven laminate _S S _H .

The term 'conventional nonwoven' is used herein simply to refer to a corresponding different layer of spunbond nonwoven that will have a lower level of resilience due to the traditional non-crimped and typically single-component fibers. However, this term is also purely qualitative and does not imply a specific maximum level of elasticity. However, the present invention assumes that the density of the high-resilience spunbond nonwoven layer is lower than the density of the standard nonwoven layer.

In one embodiment, additional layer(s) of melt atomized material may be formed on one or both surfaces of the _SH layer. Since the crimped fibers of the _SH layers may be intertwined with the substrate, such as on a spinning conveyor during fabric production , coating with a melt-blown material can improve release properties.

In one embodiment, the fabric comprises at least one layer of meltblown material (M) sandwiched between at least one layer of standard stretch spunbonded nonwoven (S _S ) and at least one one layer of spunbonded nonwoven material with high elasticity ( _SH ). Such possible SMS laminates include S _S MS _H , S _S MMS _H , S S S S MS H, S _{S MS H} S _H , S _{S S S} MMS _H , S _S MMS _{H S H ,} S _S S _S MMS laminates _H S _H , and the like.

Layers of spunbonded nonwovens with standard resilience (S _S ) can contribute to improving the mechanical stability of the laminate, for example, improving tear and puncture resistance. Layers of meltblown materials (M) can contribute to improved barrier properties, which is desirable, for example, for so-called barrier diaper cuffs for personal care products.

In the present embodiment, the present invention provides for combining good barrier properties with the soft and bulky textile character of nonwovens by combining 'traditional' spunbonded nonwovens with spunbonded nonwovens containing crimped fibers in accordance with the present invention.

Of course, in one alternative embodiment, in each of the SMS laminates discussed above, a different S _H may be used instead of all (or each layer) of S _S (S _H MS _H . and so on). The other _SH layer may be the same as or different from the first _SH layer formed by the method of the present invention. For example, it can also be formed using the method in accordance with the present invention, but using different fiber configurations (one layer S _H has a side-by-side configuration and the other a sheath-core configuration) or they can be formed using any known method obtaining S _H layers with high elasticity. This is particularly interesting for products where a high level of stealth is desired.

In one embodiment, where the method of the present invention forms part of an overall process for forming a laminate nonwoven material, the laminate material may comprise at least one layer of spunbonded nonwoven material with standard elasticity and at least one layer of spunbonded nonwoven material with high elasticity, formed in accordance with the present invention. The resulting fabrics may be of the general type S _H S _S S _H (including variants such as S _H S _S S _S S _H , S _H S _S S _H S _H , S _H S _{S S S} S _H S _H and etc). In the present embodiment, a sandwich structure is obtained comprising a first layer of high-resilience spunbond nonwoven ( _SH ) and a central layer of standard-resilience spunbond nonwoven ( _SS ) followed by another layer of high-resilience spunbond nonwoven. layer ( _SH ). This should result in a structure where, in comparison to the meltspun structure S _H MS _H , the central layer of melt-atomized material (M) is replaced by a layer S _S . The addition of a layer of substantially non-crimped standard spunbond nonwoven material S _S sandwiched between two or more layers of high resiliency spunbond nonwoven material ( _SH ) results in increased strength and stability of the material. At the same time, both outer layers of these embodiments exhibit the desirable high softness of a spunbonded nonwoven with high resiliency ( _SH ).

In yet another embodiment, the resulting fabrics may be of the general type S _H S _S (including variants such as S _S S _H , S _S S _H S _H , S _S S _S S _H S _H , and so on) . In the present embodiment, a layered structure is obtained comprising a first standard-resilience spunbond nonwoven base layer (S _S ) and a high-resilience spunbond nonwoven top layer ( _SH ). Again, adding a layer(s) of substantially non-crimped spunbonded nonwoven material with standard resilience S _S to the layer(s) of spunbonded nonwoven material with high resilience ( _SH ) results in increased strength and stability of the material while the top layer exhibits the desired high softness.

Against the background of the previously described prior art, the present invention further relates to a nonwoven material produced by the method of the present invention. The fabric may have a specific strength greater than 20 N·cm ³ ·g ^-2 and/or a density less than 6·10 ^-2 g·cm ^-3 .

Additional details and advantages of the present invention are described with reference to the figures and the following working examples. The figures show:

Figure 1: technological line for implementing the method according to the present invention (single-line);

Figure 2: another production line for implementing the method of the present invention (2 beams for spunbond nonwoven material and 2 beams for melt-atomized material);

Figure 3: Process line in Figure 2, supplemented with an Omega furnace for through-blow hot air binding; And

Figure 4: Schematic configurations of bicomponent fiber: side-by-side, eccentric sheath-core, and trilobed.

The following terms and abbreviations may be used in working examples.

MFR: melt flow rate as measured according to ISO 1133, with values shown in g/10 min and under conditions representing 230°C and 2.16 kg

MD: machine direction

CD: transverse direction

Denier: thread g/9000 m

Change in material thickness is measured in accordance with WSP.120.1 (R4), Option A.

Crimp: Typically helically crimped fibers

Necking: the tendency of materials to shrink across their width when exposed to a given rupture/stress in MD

Density: g/cm ³ units of mass per unit of volume

GSM: grams per square meter

TM: Melting point in °C, as determined according to DSC (Differential Scanning Calorimetry), method ISO 11357-3

GPC: Gel Permeation Chromatography

Specific strength: to obtain specific strength in units of H⋅cm ³ /g ² , mass per unit area is taken in grams

The values of average molecular weights ( _Mz , _Mw and _Mn ), molecular weight distribution (MWD) and its width, described using the polydispersity coefficient, PDI= _Mw / _Mn (where _Mn is the number average molecular weight and _Mw represents the weight average molecular weight) as used herein shall be understood to be determined by GPC in accordance with ISO 16014-1:2003, ISO 16014-2:2003, ISO 16014-4:2003 and ASTM D 6474-12, using the following formulas:

For a constant elution volume interval, ΔV _i , where A _i and M _i are the area of the chromatographic peak interval and the polyolefin molecular weight (MW), respectively, associated with the elution volume, V _i , where N is equal to the number of data points obtained from the chromatograms in limits of integration.

A high temperature GPC instrument is used, equipped with either an infrared (IR) detector (IR4 or IR5 from PolymerChar (Valencia, Spain) or a differential refractometer (RI) from Agilent Technologies, equipped with 3x Agilent-PLgel Olexis and 1x Agilent-PLgel Olexis Guard columns. The solvent and mobile phase used is 1,2,4-trichlorobenzene (TCB), stabilized with 250 mg/L 2,6-di-tert-butyl-4-methylphenol). The chromatography system is operated at 160°C and a constant flow rate of 1 ml/min. For one analysis, 200 μl of sample solution is injected. Data acquisition is performed using either Agilent Cirrus version 3.3 software or PolymerChar GPC-IR control software.

The column setup is calibrated using a universal calibration (in accordance with ISO 16014-2:2003) with 19 polystyrene (PS) standards with a narrow MWD ranging from 0.5 kg/mol to 11500 kg/mol. PS standards are dissolved at room temperature for several hours. Conversion of molecular weights of polystyrene peaks to molecular weights of polyolefins is carried out using the Mark-Houwink equation and the following Mark-Houwink constants:

K _PS =19 × 10 ^-3 ml/g, a _PS =0.655

K _PE =39 × 10 ^-3 ml/g, a _PE =0.725

K _PP =19 × 10 ^-3 ml/g, a _PP =0.725

A third degree polynomial fit is used to fit the calibration data.

All samples are prepared in the concentration range from 0.5 to 1 mg/ml and dissolved at 160°C for 2.5 hours.

Figure 1 illustrates a process line for implementing the method of the present invention, more specifically, a method for producing a two-component spunbond nonwoven material. The production line is equipped with two independent extruders A1 and A2, which process different polymers. The polymers are directed into the corner feed channel in separate channels. An extension head consisting of several guide plates is installed under the angular supply channel, which makes it possible to obtain various transverse fiber segments.

The typical configuration of bicomponent fibers is a sheath-core configuration. Other configurations may exist where the two polymer streams are arranged in a side-by-side configuration, an eccentric shell-core arrangement, a trilobed arrangement, and the like, as illustrated in Figure 4.

When extruder A1 processes homopolymer and extruder A2 processes random copolymer, and the die die is configured as a side-by-side configuration, helically crimped fibers are generated under certain spinning conditions.

After leaving the spinneret, the thread heads are cooled in node 1 by means of conditioned process air. The same process air is used to draw the yarns in the draw stretch unit 2 to produce yarns with the correct denier and thereby generate internal strength in the fibers by aligning the polymer chains in the same direction.

After the fibers are laid out on the spinning conveyor 4, the process air is pumped out by means of a vacuum chamber 3. The fibers are then exposed for crimping for the purpose of preliminary consolidation by means of a set of rolls, one compacting roll 5 and one support roll 6, below, on the spinning conveyor.

The resulting and pre-consolidated web 7, after leaving the pre-consolidation process, is deposited onto the spinning conveyor without applying any force and with the fibers being lightly pressed against each other, sufficient to withstand further processing.

It has been found that when processing two polymers, where one first polymer is a conventional PP homopolymer, combined with one second PP/PE random copolymer in a side-by-side arrangement, the fibers can generate helical crimp.

The resulting material 7 has a very soft feel, comparable to the feel of the well-known microfleece. Since crimped fibers from this combination of polymers produce very uniform and consistent levels of crimp, the resulting fabric from such fibers will exhibit high tensile properties.

In one example, the first polymer, the homopolymer used in A1, has a traditional spunbond quality with a narrow distribution of molecules, with M _w /M _n (polydispersity) in the range of 4.33-4.93, measured by GPC, as described in Terms and Conditions, and with an MFR measured in accordance with ISO 1133 in the range of 19-35 g/10 min, and a T _M of 159-161°C measured using DSC in accordance with ISO 11357-3. As the second polymer, a random copolymer with a M _w /M _n value (polydispersity) of 4.54 is used and, therefore, with a narrow distribution of molecules, like polymer A1. The MFR of the polymer in A2, measured in accordance with ISO 1133, is in the range of 30 g/10 min and TM at 144°C, as measured with DSC in accordance with ISO 11357-3. The second polymer is a PP/PE random copolymer containing a C2 level of approximately 4% and is nucleated to a certain extent.

The parameter settings on rolls 5 and 6 for consolidation have an important influence on the quality of the material. In methods known from the literature, consolidation rolls are typically operated at pressures and temperatures within the range of linear contact forces of 5 N/mm and temperatures of 110-130°C. When processing crimped fibers as described above under such conditions, however, the crimp is smoothed out and the materials exhibit poor thickness and softness. Therefore, in accordance with the present invention, the rollers 5 and 6 operate at temperatures and linear contact forces lower than those of the prior art.

Figures 2 and 3 show complete lines for producing spunmelt nonwovens, including a line for producing spunbond nonwovens, as described in Figure 1. In addition to line 10, as described in Figure 1, the devices additionally include lines 11 for producing melt atomized materials and a bonding apparatus 12 comprising a corrugated calender roll 13 and a back-up roll 14 and, in the case of Figure 3, a hot air through-blown Omega bonding oven 15.

All examples described below use the line as described in Figure 1.

The examples discussed below use polymers as listed in Table 1.

Table 1:

Type MFR TM (DSC) Mn Mw Mz Mw/Mn Mw/Mz g/10 min C G/
mole G/
mole G/
mole A1 Moplen HP561R Propylene homopolymer 25 161 34300 160500 333500 4.68 2.08 Borealis
HF420FB Propylene homopolymer 19 161 45150 195500 431000 4.33 2.20 Exxon 3155 Propylene homopolymer 35 159 30150 148500 307500 4.93 2.07 A2 Moplen
RP248R Propylene copolymer thirty 144 33600 152500 308000 4.54 2.02

The comparative examples discussed below use the polymers as listed in Table 2.

Table 2:

Type MFR TM (GPC) Mn Mw Mz Mw/Mn Mw/Mz g/10 min C G/
mole G/
mole G/
mole A1 Moplen HP561R Propylene homopolymer 25 161 34300 160500 333500 4.68 2.08 A2 Moplen
RP552R Propylene homopolymer 25 163 25900 176500 514000 6.81 2.91 Moplen HP561R Propylene homopolymer 25 161 34300 160500 333500 4.68 2.08

Examples 1-5:

The general conditions of the method for producing spunbond nonwoven material in examples 1-5 are as follows.

Approximately 4900 capillary openings/m

Side-by-side head die configuration

Chamber pressure 3700 Pa

Process air temperature approx. 20°C

Melt temperature A1 and A2 between 245 and 250°C

Mass flow through one capillary hole within 0.53 g/hole/min

Titre range 1.5-2.0 denier

Consolidation roller: linear contact force 2.5 N/mm and temperature 70°C

Calendering rolls: 135°C on grooved roll for spot bonding and 125°C on smooth roll with 60 N/mm linear contact force

Bonding structure: binding structure with 12.1% open dots with dot diameter 0.8mm and 24 dots/ ^cm2 , groove depth 0.75mm

The results are shown in Table 3.

Table 3:

Example Polymer A1 Polymer A2 A1/A2 ratio Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm TEMD
% TSCD
N/50 mm TECD
% 10 Exxon 3155 RP248R 50/50 20.6 0.37 0.0557 29.2 74.9 17.5 78.0 2 Exxon 3155 RP248R 70/30 21.2 0.33 0.0642 33.2 56.2 17.8 62.4 3 HP561R RP248R 50/50 20.7 0.42 0.0493 27.8 104.0 17.0 119.0 4 HP561R RP248R 70/30 20.6 0.35 0.0589 36.7 96.8 25.4 116.8 5 HF420FB RP248R 50/50 20.0 0.44 0.0455 26.9 135 17.8 137.0

Above you can see the results of studies of the parameters of the resulting material with varying combinations of A1/A2 polymers in the MFR range of 35/30 g/10 min, 25/30 g/10 min and 19/30 g/10 min. As can be seen, all combinations generate crimp in the sense that the thickness is measured from 0.33 mm to 0.44 mm. The tensile properties in MD are positively high and the elongation properties remain at an acceptable low level.

Examples 6-10:

The general process conditions for the spunbond nonwoven fabric production method in Examples 6-10 are as follows.

Approximately 4900 capillary openings/m

Side-by-side head die configuration

Chamber pressure 3700 Pa

Process air temperature approx. 20°C

Melt temperature A1 and A2 between 245 and 250°C

Mass flow through one capillary hole ranging from 0.53 g/hole/min

Titre range 1.5-2.0 denier

Consolidation roller: linear contact force 2.5 N/mm and temperature 40°C

Calendering rolls: 135°C on grooved roll for spot bonding and 125°C on smooth roll with 60 N/mm linear contact force

Bonding structure: binding structure with 12.1% open dots with dot diameter 0.8mm and 24 dots/ ^cm2 , groove depth 0.75mm

The results are shown in Table 4.

Table 4:

Example Polymer A1 Polymer A2 A1/A2 ratio Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm TEMD
% TSCD
N/50 mm TECD
% 6 HP561R RP248R 40/60 21.5 0.60 0.0358 21.4 121 12.7 129 7 HP561R RP248R 50/50 21.9 0.49 0.0447 32.3 137 17.5 129 8 HP561R RP248R 60/40 20.9 0.36 0.0581 35.4 112 21.4 131 9 HP561R RP248R 70/30 20.1 0.34 0.0591 45.3 112 26.0 125 10 HP561R RP248R 80/20 20.0 0.34 0.0588 48.3 100 26.7 103

The illustrative list above shows the results of varying the polymer ratios between A1 and A2, but holding all other parameters constant, the consolidation rollers operate in all versions at a contact force of 2.5 N/mm and at a temperature of approximately 40°C.

Note that the maximum level of crimp is observed for the 40/60 ratio version where the thickness is measured at 0.6mm, but this ratio is also noted to produce relatively low tensile properties ranging from 21.4N/50mm in MD and 12.7 N/50 mm on CD.

Examples 11-17:

The general process conditions for the spunbond nonwoven fabric production method in Examples 11-17 are as follows.

Approximately 4900 capillary openings/m

Side-by-side head die configuration

Chamber pressure 3700 Pa

Process air temperature approx. 20°C

Melt temperature A1 and A2 between 245 and 250°C

Mass flow through one capillary hole ranging from 0.53 g/hole/min

Titre range 1.5-2.0 denier

Consolidation roller: linear contact force 2.5 N/mm and temperature range 50°C-110°C

Calendering rolls: 135°C on grooved roll for spot bonding and 125°C on smooth roll with 60 N/mm linear contact force

Bonding structure: binding structure with 12.1% open dots with dot diameter 0.8mm and 24 dots/ ^cm2 , groove depth 0.75mm

The results are shown in Table 5.

Table 5:

Example Polymer A1 Polymer A2 A1/A2 ratio TM°C Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm TEMD % TSCD
N/50 mm TECD
% eleven HF420FB RP248R 50/
50 50 20.0 0.476 0.0420 25.7 130 18.1 154 12 HF420FB RP248R 50/
50 60 19.7 0.476 0.0414 27.0 136 17.1 138 13 HF420FB RP248R 50/
50 71 20.0 0.470 0.0426 28.0 139 17.3 149 14 HF420FB RP248R 50/
50 82 20.2 0.448 0.0451 27.3 130 17.4 156 15 HF420FB RP248R 50/
50 91 19.8 0.432 0.0458 26.5 132 18.8 165 16 HF420FB RP248R 50/
50 97 20.0 0.370 0.0541 27.6 135 17.7 152 17 HF420FB RP248R 50/
50 110 19.8 0.358 0.0553 26.0 126 17.1 151

In Examples 11-17 above, all process parameters are kept the same with the exception of the temperature at the consolidation roller. The rollers in all versions operate at a contact force of 2.5 N/mm and the temperatures are adjusted in increments from 50°C to 110°C in steps of approximately 10°C.

Examples 18-23:

The general process conditions for the spunbond nonwoven fabric production method in Examples 18-23 are as follows.

Approximately 4900 capillary openings/m

Side-by-side head die configuration

Chamber pressure 3700 Pa

Process air temperature approx. 20°C

Melt temperature A1 and A2 between 245 and 250°C

Mass flow through one capillary hole ranging from 0.53 g/hole/min

Titre range 1.5-2.0 denier

Consolidation roller: linear contact force 2.5 N/mm and temperature 40°C

Calendering rolls: 135°C on grooved roll for spot bonding and 125°C on smooth roll with 60 N/mm linear contact force

Bonding structure: binding structure with 12.1% open dots with dot diameter 0.8mm and 24 dots/ ^cm2 , groove depth 0.75mm

The results are shown in Table 6.

Table 6:

Example Polymer A1 Polymer A2 A1/A2 ratio Tem. ovens
°C Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm TEMD
% TSCD
N/50 mm TECD
% 118 HF420FB RP248R 50/
50 120 19.0 0.39 0.0487 28.8 113.6 16.8 132.2 119 HF420FB RP248R 50/
50 125 19.3 0.42 0.0460 30.2 109.9 17.1 129.7 220 HF420FB RP248R 50/
50 130 20.0 0.41 0.0488 29.5 99.6 15.9 122.0 221 HF420FB RP248R 50/
50 135 20.9 0.38 0.0550 31.5 99.3 15.7 121.8 222 HF420FB RP248R 50/
50 140 19.5 0.38 0.0513 30.1 97.1 14.9 137.1 223 HF420FB RP248R 50/
50 145 20.0 0.40 0.0500 29.2 71.4 12.8 130.0

In the examples discussed above, all process parameters are held constant and the crimped, consolidated and calendered web is finally activated in the oven using a through-air bonding process, where the air flow through the consolidated web is held constant and the air temperature in the oven varies from 120°C to 145° C.

General observations of the processing versions listed in Examples 1-23:

Various combinations of polymer ratios are processed without any negative observations. The conditions of the method are very stable and make it possible to implement it smoothly, including transitions from one version to another. In the spinning process, the curtain of fibers is stable under all conditions and there is no fiber breakage resulting in drips or drips.

Comparative examples 24-26:

The general process conditions for the spunbond nonwoven fabric production method in Comparative Examples 24 to 26 are as follows.

Approximately 4900 capillary openings/m

Side-by-side head die configuration

Chamber pressure 4000 Pa

Process air temperature approx. 18°C

Melt temperature A1 and A2 between 245 and 248°C

Mass flow through one capillary hole ranging from 0.58 g/hole/min

Titre range 1.5-2.0 denier

Consolidation roller: linear contact force of 2.5 N/mm and temperature varying from 41 to 88°C

Calendering rolls: 160°C on the grooved roll for spot bonding and 145°C on the smooth roll with a linear contact force of 60 N/mm

Bonding structure: binding structure with 12.1% open dots with dot diameter 0.8mm and 24 dots/ ^cm2 , groove depth 0.75mm

The results are shown in Table 7.

Table 7:

Example Polymer A1 Polymer A2 A1/A2 ratio CR
C Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm TEMD
% TSCD
N/50 mm TECD
% 24 HP561R HP552R/
HP561R 70/30
(50/50) 41 20.4 0.66 0.0309 18.1 91.3 9.4 123.9 25 HP561R HP552R/
HP561R 70/30
(50/50) 62 20.6 0.67 0.0307 15.1 107.1 10.4 132.7 26 HP561R HP552R/
HP561R 70/30
(50/50) 88 20.5 0.65 0.0315 15.8 109.5 9.5 126.9

Shown above are data obtained from the reference versions, from a well-known crimped consolidated PP/PP style fabric with an aggressive crimp. The polymer ratios between A1 and A2 are 70/30, and a polymer mixture of 50% HP561R and 50% HP552R (narrow and broad mass distribution) is injected into extruder A2. All process parameters are kept constant, with the exception of the temperature of the consolidation roll. The consolidation roller is maintained at a constant linear contact force of 2.5 N/50 mm, but the temperature varies from 41°C to 88°C. The calendering temperature is 160°C on a grooved roll and 145°C on a smooth roll.

Examples 27-31 and Comparative Example 32:

These examples serve to demonstrate the superior strength-to-weight ratio of nonwovens produced in accordance with the present invention. Examples are shown in Table 8.

Table 8:

Example Polymer A1 Polymer A2 A1/A2 ratio Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50mm Specific strength
N⋅cm ³ /g ² 27 HP561R RP248R 40/60 21.5 0.60 0.0358 21.4 27.9 28 HP561R RP248R 50/50 21.9 0.49 0.0447 32.3 33.3 29 HP561R RP248R 60/40 20.9 0.36 0.0581 35.4 29.2 thirty HP561R RP248R 70/30 20.1 0.34 0.0591 45.3 38.0 31 HP561R RP248R 80/20 20.0 0.34 0.0588 48.3 41.2 32 HF420FB N.A. 100 19.3 0.31 0.0623 50.4 42.1

Comparative Example 32 is a reference one-component material that is processed at significantly higher calender bonding temperatures at 162°C (calender oil temperature) for a grooved roll and at 145°C (calender oil temperature) for a smooth roll. All other examples are carried out at 135°C (calender oil temperature) for the grooved roll and at 125°C (calender oil temperature) for the smooth roll. All other established parameters of the method are identical.

From the above it can be seen that the maximum obtainable tensile strength in MD is 50.4 N/50 mm, which is measured for the non-crimp version (Comparative Example 32), this results in a specific strength of 42.1 N cm ³ /g ² . It can be seen that for lower density versions at different polymer ratios and at lower densities due to crimped fibers, the absolute tensile strength decreases, resulting in a decrease in specific strength. The optimum relationship between crimp/softness/thickness and specific strength was found for a 50/50 ratio of polymers, homopolymer and copolymer, resulting in a specific strength of 33.3 Ncm ³ /g ² .

The specific strength is compensated for the individual density and bulk of the materials.

Comparative examples 33-35:

These examples constitute reference versions of high elasticity for specific strength. Examples are shown in Table 9.

Table 9:

Example Polymer A1 Polymer A2 A1/A2 ratio CR
C Bw gsm Thickness
mm Density
g/cm ³ TSMD
N/50 mm Specific strength N⋅cm ³ /g ² 33 HP561R HP552R 70/30 90 21.1 0.43 0.0500 21.1 22.7 34 Exxon 3155 HP552R 70/30 90 20.6 0.42 0.0490 21.4 21.3 35 HP561R HP552R/
HP561R 70/30
(50/50) 88 20.5 0.65 0.0315 15.8 24.5

The following Table 10 compares the specific strength parameters obtained for examples 27-35 discussed above. Comparative Example 32 is considered to be the optimum for what is possible under the given process conditions, and this specific strength is set to 100% for the ranges for the other high-resilience versions, which is calculated as follows.

Table 10:

Example Polymer A1 Polymer A2 A1/A2 ratio Specific strength
N⋅cm ³ /g ² Grade 32 HF420FB N.A. 100 42.1 100 27 HP561R RP248R 40/60 27.9 66.2 28 HP561R RP248R 50/50 33.3 79.1 29 HP561R RP248R 60/40 29.2 69.4 thirty HP561R RP248R 70/30 38.0 90.2 31 HP561R RP248R 80/20 41.2 97.9 33 HP561R HP552R 70/30 22.7 53.7 34 Exxon 3155 HP552R 70/30 21.3 50.5 35 HP561R HP552R/HP561R 70/30 (50/50) 24.5 58.2

The materials of the present invention have been found to have high specific strength. As shown in Example 28 with a 50/50 ratio of two different polymers, this appears to represent the best estimate at scale when low density/high thickness is at the same time a priority. Apparently, when the ratio of the two polymers changes from a 50/50 blend towards a more one-component blend that generates less crimp, the specific tensile strength increases, and in reality, the 80/20 blend version is very close to a conventional single-component material in terms of specific strength.

When comparing basic PP/PP crimped nonwovens made from two homopolymers with different molecular weight distributions (one distribution is narrow and the other is broader), it is clear that these versions perform poorly when scaled up relative to specific strength. All versions, both medium and aggressive crimp, range between 50.5 and 58.2 on the scale, with 100 representing the maximum value for a single-component material. The materials of the present invention, by comparison, are close to 80% at this scale.

Claims (18)

1. A spunbonded nonwoven fabric containing crimped multicomponent fibers, including a first component that contains a PP homopolymer and a second component that contains a PP/PE copolymer, and obtained by a process including continuously spinning the multicomponent fibers, directing the multicomponent fibers onto a spinning conveyor using baffles and/or air flows, laying the multicomponent fibers onto a spinning conveyor, and preconsolidating the multicomponent fibers after laying out using one or more preconsolidation rolls to form a preconsolidated web, wherein the preconsolidation rolls are operated at a temperature of 91°C or lower and at linear contact force is less than 5 N/mm and where the material has a specific strength greater than 20 N⋅cm ³ ⋅g ^-2 and/or a density less than 6⋅10 ^-2 g⋅cm ^-3 . 2. The spunbonded nonwoven fabric according to claim 1, wherein the preconsolidation rolls operate at 20°C to below 91°C. 3. Spunbonded nonwoven material according to claim 1, where the pre-consolidation rollers operate at a linear contact force of 1-4 N/mm. 4. Spunbonded nonwoven fabric according to claim 1, in which the content of ethylene-derived repeating units in the PP/PE copolymer is >0-5% by weight. 5. Spunbonded nonwoven material according to claim 1, wherein the PP/PE copolymer is a random copolymer. 6. Spunbonded nonwoven fabric according to claim 1, wherein the PP homopolymer is isotactic. 7. Spunbonded nonwoven material according to claim 1, in which the melt flow rates and/or polydispersity of the PP homopolymer and the PP/PE copolymer differ by less than 30%. 8. The spunbond nonwoven fabric according to claim 1, wherein the melting temperatures of the PP homopolymer and the PP/PE copolymer differ by 10°C or more. 9. The spunbonded nonwoven fabric of claim 1, wherein the multicomponent fibers are bicomponent fibers and/or have a side-by-side configuration. 10. Spunbonded nonwoven material according to claim 1, in which the mass ratio of the first and second components is 40/60-80/20. 11. Spunbonded nonwoven fabric according to claim 1, where the method further includes binding the pre-consolidated web using one or more calendering rolls, at least one of which is grooved, and/or binding through hot air blowing. 12. The spunbonded nonwoven fabric according to claim 11, wherein the calendering rolls operate at a temperature of 120-145°C and/or the air used for binding through hot air blowing has a temperature of 120-145°C. 13. Spunbonded nonwoven material according to claim 1, where the pre-consolidation rollers operate at a temperature of 40-90°C. 14. Spunbonded nonwoven material according to claim 1, where the pre-consolidation rollers operate at a temperature of 55-75°C. 15. Spunbonded nonwoven material according to claim 1, where the pre-consolidation rollers operate at a linear contact force of 1-2.5 N/mm. 16. Spunbonded nonwoven material according to claim 1, in which the melt flow rates and/or polydispersity of the PP homopolymer and the PP/PE copolymer differ by less than 20%. 17. The spunbond nonwoven fabric according to claim 1, wherein the melting temperatures of the PP homopolymer and the PP/PE copolymer differ by 20°C or less. 18. Spunbonded nonwoven material according to claim 1, in which the mass ratio of the first and second components is 40/60-60/40.