U.S. patent application number 13/730262 was filed with the patent office on 2014-07-03 for elastic nonwovens with improved haptics and mechanical properties.
This patent application is currently assigned to Dow Brasil S.A.. The applicant listed for this patent is DOW BRASIL S.A., DOW GLOBAL TECHNOLOGIES LLC. Invention is credited to Andy C. Chang, Gert J. Claasen, Angels Domenech, Emil Hersche, Edward N. Knickerbocker, Hong Peng, Aleksandar Stoiljkovic, Jozef J. Van Dun.
Application Number | 20140187114 13/730262 |
Document ID | / |
Family ID | 49920676 |
Filed Date | 2014-07-03 |
United States Patent
Application |
20140187114 |
Kind Code |
A1 |
Peng; Hong ; et al. |
July 3, 2014 |
ELASTIC NONWOVENS WITH IMPROVED HAPTICS AND MECHANICAL
PROPERTIES
Abstract
The present invention is an extensible nonwoven comprising a
polyolefin elastomer fiber wherein the surface of the fiber further
comprises an inorganic filler or PDMS or combinations thereof,
wherein the inorganic filler, if present, has D-90 particle size of
5 microns or less.
Inventors: |
Peng; Hong; (Columbus,
OH) ; Hersche; Emil; (Wollerau, CH) ; Van Dun;
Jozef J.; (Horgen, CH) ; Knickerbocker; Edward
N.; (Lake Jackson, TX) ; Chang; Andy C.;
(Houston, TX) ; Domenech; Angels; (Sao Paulo,
BR) ; Stoiljkovic; Aleksandar; (Waedenswil, CH)
; Claasen; Gert J.; (Richterswil, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DOW GLOBAL TECHNOLOGIES LLC
DOW BRASIL S.A. |
Midland
Sao Paulo - Sp |
MI |
US
BR |
|
|
Assignee: |
Dow Brasil S.A.
Sao Paulo - Sp
MI
Dow Global Technologies LLC
Midland
|
Family ID: |
49920676 |
Appl. No.: |
13/730262 |
Filed: |
December 28, 2012 |
Current U.S.
Class: |
442/329 |
Current CPC
Class: |
Y10T 442/602 20150401;
D04H 3/16 20130101; D04H 3/007 20130101; D01F 6/46 20130101; D01F
1/10 20130101; D01F 8/06 20130101; D04H 3/147 20130101; D04H 13/00
20130101 |
Class at
Publication: |
442/329 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Claims
1. An extensible nonwoven comprising a polyolefin elastomer fiber
wherein the surface of the fiber further comprises an inorganic
filler or PDMS or combinations thereof, wherein the inorganic
filler, if present, has D-90 particle size of 5 microns or
less.
2. The extensible nonwoven of claim 1 wherein the inorganic filler,
if present, has D-90 particle size of 2 microns or less.
3. The extensible nonwoven of claim 1 wherein the polyolefin
elastomer is selected from the group consisting of propylene based
plastomers or elastomers (PBPEs) and olefin block copolymers
(OBCs).
4. The extensible nonwoven of claim 1 wherein the inorganic filler
is present and is selected from the group consisting of CaCO.sub.3,
AlSiO.sub.3, talc, and untreated fused silica.
5. The extensible nonwoven of claim 1 wherein the fiber is a
monocomponent fiber and CaCO.sub.3 is present in an amount of from
1 to 15% by weight of the fiber.
6. The extensible nonwoven of claim 1 wherein the fiber is a
monocomponent fiber and untreated fused silica is present in an
amount of from 0.25 to 5% by weight of the fiber.
7. The extensible nonwoven of claim 1 wherein the fiber is a
bicomponent fiber in the form of sheath/core and CaCO.sub.3 is
present in an amount of from 5 to 50 percent by weight of the
sheath.
8. The extensible nonwoven of claim 1 wherein the fiber is a
bicomponent fiber in the form of sheath/core and AlSiO.sub.3 is
present in an amount of from 5 to 30 percent by weight of the
sheath.
9. The extensible nonwoven of claim 1 wherein the fiber is a
bicomponent fiber and an inorganic filler is present in an amount
of from 2 to 15 percent by weight of the fiber.
10. The extensible nonwoven of claim 1 wherein polydimethylsiloxane
is present and has an average particle size when in powder form of
between 2 and 5 microns.
11. The extensible nonwoven of claim 1 wherein the fiber is a
monocomponent fiber and polydimethylsiloxane is present in an
amount of from 0.5 to 1% by weight of the fiber.
12. The extensible nonwoven of claim 1 wherein the fiber is a
bicomponent fiber in the form of sheath/core and
polydimethylsiloxane is present in an amount of from 0.5 to 10 by
weight of the sheath.
Description
FIELD OF INVENTION
[0001] The present invention relates to nonwoven fabrics having
improved haptics while maintaining mechanical performance
BACKGROUND AND SUMMARY OF INVENTION
[0002] Propylene-based polymers, particularly homo-polypropylene
(hPP) are well known in the art, and have long been used in the
manufacture of fibers. Fabrics made from hPP, particularly nonwoven
fabrics, exhibit high modulus but poor elasticity. These fabrics
are commonly incorporated into multicomponent articles, e.g.,
diapers, wound dressings, feminine hygiene products and the like.
While polyethylene-based elastomers, and the fibers and fabrics
made from these polymers, exhibit low modulus and good elasticity,
they also exhibit poor tenacity, stickiness and hand feel which are
generally considered to be unacceptable for commercial
applications.
[0003] Tenacity is important because the manufacture of
multicomponent articles typically involves multiple steps (e.g.,
rolling/unrolling, cutting, adhesion, etc.). Fibers with a high
tensile strength are advantaged over fibers with a low tensile
strength because the former will experience fewer line breaks (and
thus greater productivity). Moreover, the end-use typically
requires a level of tensile strength specific to the function of
the component. Optimized fabrics have the minimum material
consumption (basis weight) to achieve the minimum required tensile
strength for the manufacture and end-use of the fiber, component
(e.g., nonwoven fabric) and article.
[0004] Low modulus is one aspect of hand feel. Fabrics made from
fibers with a low modulus will feel "softer", all else equal, than
fabrics made from fibers with a high modulus. A fabric comprised of
lower modulus fibers will also exhibit lower flexural rigidity
which translates to better drapability and better fit. In contrast,
a fabric made from a higher modulus fiber, e.g., hPP, will feel
harsher (stiffer) and will drape less well (e.g., it will have a
poorer fit). However, fabrics made from polyethylene-based
elastomers tend to feel tacky and clammy to the skin.
[0005] 63635
[0006] Fiber elasticity is also important because it translates to
better comfort-fit as the article made from the fiber will be more
body conforming. Diapers with elastic components will have less
sagging in general as body size and shape and movement vary. With
improved fit, the general well being of the user is improved
through improved comfort, reduced leakage and a closer resemblance
of the article to cotton underwear.
[0007] Most elastomeric materials have been characterized as having
an undesirable rubbery touch or waxy feel. Not surprisingly,
elastic nonwoven fabrics made from such materials also possess
texture that is perceived by end-users and sticky, rubbery or
waxy.
[0008] Thus new nonwoven fabrics are desired which are extensible,
durable, and have improved haptics. It has been discovered that
using olefin based elastomers with different additives improved the
perceptions of materials without unduly affecting the mechanical
performance of the fabrics. Accordingly, in one aspect, the present
invention is an extensible nonwoven comprising a polyolefin
elastomer fiber wherein the surface of the fiber further comprises
an inorganic filler or PDMS or combinations thereof, wherein the
inorganic filler, if present, has D-90 particle size of 5 microns
or less.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a set of SEM images of nonwovens with different
fillers according the present invention
DETAILED DESCRIPTION OF THE INVENTION
[0010] As used herein, the term "nonwoven web" or "nonwoven fabric"
or "nonwoven", refers to a web that has a structure of individual
fibers or threads which are interlaid, but not in any regular,
repeating manner. Nonwoven webs have been formed by a variety of
processes, such as, for example, air laying processes, meltblowing
processes, spunbonding processes and carding processes, including
bonded carded web processes.
[0011] As used herein, the term "meltblown", refers to the process
of extruding a molten thermoplastic material through a plurality of
fine, usually circular, die capillaries as molten threads or
filaments into a high velocity gas (e.g., air) stream which
attenuates the filaments of molten thermoplastic material to reduce
their diameter, which may be to a microfiber diameter. Thereafter,
the meltblown fibers are carried by the high velocity gas stream
and are deposited on a collecting surface to form a web of randomly
dispersed meltblown fibers.
[0012] As used herein, the term "spunbonded", refers to the process
of extruding a molten thermoplastic material as filaments from a
plurality of fine, usually circular, capillaries of a spinneret
with the diameter of the extruded filaments then being rapidly
reduced by drawing the fibers and collecting the fibers on a
substrate.
[0013] As used herein, the term "microfibers", refers to small
diameter fibers having an average diameter not greater than about
100 microns. Fibers, and in particular, spunbond and meltblown
fibers used in the present invention can be microfibers. More
specifically, the spunbond fibers can advantageously be fibers
having an average diameter of about 14-28 microns, and having a
denier from about 1.2-5.0, whereas the meltblown fibers can
advantageously be fibers having an average diameter of less than
about 15 microns, or more advantageously be fibers having an
average diameter of less than about 12 microns, or even more
advantageously be fibers having an average diameter of less than
about 10 microns. It also contemplated that the meltblown fibers
may have even smaller average diameters, such as less than 5
microns.
[0014] As used herein, the term "polymer" generally includes, but
is not limited to, homopolymers, copolymers, such as, for example,
block, graft, random and alternating copolymers, terpolymers, etc.,
and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometrical configurations of the material. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
[0015] "Polyethylene" shall mean polymers comprising greater than
50% by weight of units which have been derived from ethylene
monomer. This includes polyethylene homopolymers or copolymers
(meaning units derived from two or more comonomers). Common forms
of polyethylene known in the art include Low Density Polyethylene
(LDPE); Linear Low Density Polyethylene (LLDPE); Medium Density
Polyethylene (MDPE); and High Density Polyethylene (HDPE). These
polyethylene materials are generally known in the art; however the
following descriptions may be helpful in understanding the
differences between some of these different polyethylene resins
[0016] The term "LDPE" may also be referred to as "high pressure
ethylene polymer" or "highly branched polyethylene" and is defined
to mean that the polymer is partly or entirely homopolymerized or
copolymerized in autoclave or tubular reactors at pressures above
14,500 pounds per square inch (psi) [100 megapascals (MPa)] with
the use of free-radical initiators, such as peroxides (see for
example U.S. Pat. No. 4,599,392, herein incorporated by reference).
LDPE resins typically have a density in the range of 0.916 to 0.940
grams per cubic center (g/cm.sup.3).
[0017] "LLDPE" refers to linear ethylene alpha olefin copolymers
having a density in the range of from about 0.855 about 0.912
g/cm.sup.3 to about 0.925 g/cm.sup.3. "LLDPE" may be made using
chromium, Ziegler-Natta, metallocene, constrained geometry, or
single site catalysts. The term "LLDPE" includes znLLDPE, uLLDPE,
and mLLDPE. "znLLDPE" refers to linear polyethylene made using
Ziegler-Natta or chromium catalysts and typically has a density of
from about 0.912 to about 0.925 g/cm.sup.3 and a molecular weight
distribution greater than about 2.5, "uLLDPE" or "ultra linear low
density polyethylene" refers to linear polyethylene having a
density of less than 0.912 g/cm.sup.3, but which is made using
chromium or Ziegler-Natta catalysts and thus typically have a
molecular weight distribution ("MWD") greater than 2.5. "mLLDPE"
refers to LLDPE made using metallocene, constrained geometry, or
single site catalysts. These polymers typically have a molecular
weight distribution ("MWD") in the range of from 1.5 to 8.0. These
resins will typically have a density in the range of from about
0.855 to 0.925 g/cm.sup.3. The alpha olefin monomer to be
copolymerized with the ethylene monomer is preferably an alpha
olefin having from 3 to 20 carbon atoms. Preferred copolymers
include 1-hexene and 1-octene.
[0018] "MDPE" refers to linear polyethylene having a density in the
range of from greater than 0.925 g/cm.sup.3 to about 0.940
g/cm.sup.3. "MDPE" is typically made using chromium or
Ziegler-Natta catalysts or using metallocene, constrained geometry,
or single cite catalysts, and typically have a molecular weight
distribution ("MWD") greater than 2.5.
[0019] "HDPE" refers to linear polyethylene having a density in the
range greater than or equal to 0.940 g/cm.sup.3. "HDPE" is
typically made using chromium or Ziegler-Natta catalysts or using
metallocene, constrained geometry, or single cite catalysts and
typically have a molecular weight distribution ("MWD") greater than
2.5.
[0020] "Polypropylene" shall mean polymers comprising greater than
50% by weight of units which have been derived from propylene
monomer. This includes homopolymer polypropylene, random copolymer
polypropylene, impact copolymer polypropylene, and propylene based
plastomers and elastomers. These polypropylene materials are
generally known in the art.
[0021] As used herein, the term "polypropylene based plastomers
(PBP) or elastomers (PBE)" (collectively, these may be referred to
as "PBPE") includes reactor grade copolymers of propylene having
heat of fusion less than about 100 Joules/gram (J/g) as measured
using differential scanning Calorimetry (DSC) and MWD<3.5. The
PBPs generally have a heat of fusion less than about 100 J/g while
the PBEs generally have a heat of fusion less than about 40 J/g.
The PBPs typically have a weight percent ethylene in the range of
about 3 to about 10 weight percent (wt %) ethylene, with the
elastomeric PBEs having an ethylene content of from about 10 to 15
wt % ethylene.
[0022] As used herein, the term "extensible" refers to any nonwoven
material which, upon application of a biasing force, is able to
undergo elongation to at least about 50 percent strain and more
preferably at least about 70 percent strain without experiencing
catastrophic failure.
[0023] As used herein, the term "tensile strength" describes the
peak force for a given basis weight when pulled in either the
machine direction (MD) or cross direction (CD) of a nonwoven when
pulled to break. The peak force may or may not correspond to the
force at break or strain at break. "Elongation" unless otherwise
specified, refers to the strain corresponding to the tensile
strength.
[0024] The following analytical methods are used in the present
invention:
[0025] Density is determined in accordance with ASTM D792.
[0026] "Melt index" also referred to as "MI" or "I.sub.2" is
determined according to ASTM D1238 (190.degree. C., 2.16 kg). "Melt
flow rate" or "MFR" is determined according to ASTM D1238
(230.degree. C., 2.16 kg). Melt index is generally associated with
polyethylene polymers, while melt flow rate is associated with
propylene based polymers
[0027] "Softness" is determined using the Handle-o-meter
(manufactured by Edana, part number WSP 90.3 (05)). The method uses
10.times.10 cm, min 3 samples, a slit width of 5 mm, and an arm
weight of 100 grams. Measurements are done in machine direction
(MD) and cross-direction stiffness (CD), and reported as
combination or for specific direction.
[0028] "D-90" refers to the Particle Size at which 90% of the
particles in a cumulative particle size distribution will be less
than or equal to the value. Thus in a particle size distribution
having a D-90 of 5 microns, 90% of the particles will have a
particle size of 5 microns or less.
[0029] "Particle Size"--dynamic light scattering (DLS) is used for
accurately determining the particle size distribution according to
ISO 22412:2008 which specifies a method for the application of DLS
to the estimation of an average particle size and the measurement
of the broadness of the size distribution as well as the D10, D50
and D90 of mainly sub micrometer-sized particles or droplets
dispersed in liquids.
[0030] Differential scanning calorimetry (DSC) is a common
technique that can be used to examine the melting and
crystallization of semi-crystalline polymers. General principles of
DSC measurements and applications of DSC to studying
semi-crystalline polymers are described in standard texts (e.g., E.
A. Turi, ed., Thermal Characterization of Polymeric Materials,
Academic Press, 1981). Certain of the copolymers of this invention
are characterized by a DSC curve with a T.sub.m that remains
essentially the same and a T.sub.max that decreases as the amount
of unsaturated comonomer in the copolymer is increased. Tm (or
alternatively T.sub.me) means the temperature at which the melting
ends. T.sub.max means the peak melting temperature.
[0031] Differential Scanning Calorimetry (DSC) analysis is
determined using a model Q1000 DSC from TA Instruments, Inc.
Calibration of the DSC is done as follows. First, a baseline is
obtained by running the DSC from -90.degree. C. to 290.degree. C.
without any sample in the aluminum DSC pan. Then 7 milligrams (mg)
of a fresh indium sample is analyzed by heating the sample to
180.degree. C., cooling the sample to 140.degree. C. at a cooling
rate of 10.degree. C./min followed by keeping the sample
isothermally at 140.degree. C. for 1 minute, followed by heating
the sample from 140.degree. C. to 180.degree. C. at a heating rate
of 10.degree. C./min The heat of fusion and the onset of melting of
the indium sample are determined and checked to be within
0.5.degree. C. from 156.6.degree. C. for the onset of melting and
within 0.5 J/g from 28.71 J/g for the heat of fusion. Then
deionized water is analyzed by cooling a small drop of fresh sample
in the DSC pan from 25.degree. C. to -30.degree. C. at a cooling
rate of 10.degree. C./min The sample is kept isothermally at
-30.degree. C. for 2 minutes and heated to 30.degree. C. at a
heating rate of 10.degree. C./min The onset of melting is
determined and checked to be within 0.5.degree. C. from 0.degree.
C.
[0032] The samples are pressed into a thin film at a temperature of
190.degree. C. About 5 to 8 mg of sample is weighed out and placed
in the DSC pan. The lid is crimped on the pan to ensure a closed
atmosphere. The sample pan is placed in the DSC cell and the heated
at a high rate of about 100 degrees Celsius per minute (.degree.
C./min) to a temperature of about 30 60.degree. C. above the melt
temperature. The sample is kept at this temperature for about 3
minutes. Then the sample is cooled at a rate of 10.degree. C./min
to -40.degree. C., and kept isothermally at that temperature for 3
minutes. Consequently the sample is heated at a rate of 10.degree.
C./min until complete melting. The resulting enthalpy curves are
analyzed for peak melt temperature, onset and peak crystallization
temperatures, heat of fusion and heat of crystallization, Tme, and
any other DSC analyses of interest.
[0033] Molecular weight and molecular weight distributions of the
propylene-alpha olefin copolymers are determined using gel
permeation chromatography (GPC) on a Polymer Laboratories
PL-GPC-220 high temperature chromatographic unit equipped with four
linear mixed bed columns (Polymer Laboratories (20-micron particle
size)). The oven temperature is at 160.degree. C. with the
autosampler hot zone at 160.degree. C. and the warm zone at
145.degree. C. The solvent is 1,2,4-trichlorobenzene containing 200
ppm 2,6-di-t-butyl-4-methylphenol. The flow rate is 1.0
milliliter/minute and the injection size is 100 microliters. About
0.2% by weight solutions of the samples are prepared for injection
by dissolving the sample in nitrogen purged 1,2,4-trichlorobenzene
containing 200 ppm 2,6-di-t-butyl-4-methylphenol for 2.5 hrs at
160.degree. C. with gentle mixing.
[0034] The molecular weight determination is deduced by using ten
narrow molecular weight distribution polystyrene standards (from
Polymer Laboratories, EasiCal PS1 ranging from 580-7,500,000
g/mole) in conjunction with their elution volumes. The equivalent
propylene-alpha olefin copolymer molecular weights are determined
by using appropriate Mark-Houwink coefficients for polypropylene
(as described by Th. G. Scholte, N. L. J. Meijerink, H. M.
Schoffeleers, and A.M.G. Brands, J. Appl. Polym. Sci., 29,
3763-3782 (1984)) and polystyrene (as described by E. P. Otocka, R.
J. Roe, N. Y. Hellman, P. M. Muglia, Macromolecules, 4, 507 (1971))
in the Mark-Houwink equation:
{N}=KMa
[0035] where Kpp=1.90E-04 , app=0.725 and Kps=1.26E-04,
aps=0.702.
[0036] Standard CRYSTAF Method:
[0037] Branching distributions are determined by crystallization
analysis fractionation (CRYSTAF) using a CRYSTAF 200 unit
commercially available from Polymer Char, Valencia, Spain. The
samples are dissolved in 1,2,4 trichlorobenzene at 160.degree. C.
(0.66 mg/mL) for 1 hr and stabilized at 95.degree. C. for 45
minutes. The sampling temperatures range from 95 to 30.degree. C.
at a cooling rate of 0.2.degree. C./min An infrared detector is
used to measure the polymer solution concentrations. The cumulative
soluble concentration is measured as the polymer crystallizes while
the temperature is decreased. The analytical derivative of the
cumulative profile reflects the short chain branching distribution
of the polymer.
[0038] The CRYSTAF peak temperature and area are identified by the
peak analysis module included in the CRYSTAF Software (Version
2001.b, Polymer Char, Valencia, Spain). The CRYSTAF peak finding
routine identifies a peak temperature as a maximum in the dW/dT
curve and the area between the largest positive inflections on
either side of the identified peak in the derivative curve. To
calculate the CRYSTAF curve, the preferred processing parameters
are with a temperature limit of 70.degree. C. and with smoothing
parameters above the temperature limit of 0.1, and below the
temperature limit of 0.3, analytical temperature-rising elution
fractionation (ATREF) Peak Comonomer Composition Measurement by
Infra-Red Detector. The comonomer composition of the
temperature-rising elution fractionation (TREF) peak can be
measured using an IR4 infra-red detector available from Polymer
Char, Valencia, Spain (http://www.polymerchar.com/).
[0039] The "composition mode" of the detector is equipped with a
measurement sensor (CH.sub.2) and composition sensor (CH.sub.3)
that are fixed narrow band infra-red filters in the region of
2800-3000 cm.sup.-1. The measurement sensor detects the methylene
(CH.sub.2) carbons on the polymer (which directly relates to the
polymer concentration in solution) while the composition sensor
detects the methyl (CH.sub.3) groups of the polymer. The
mathematical ratio of the composition signal (CH.sub.3) divided by
the measurement signal (CH.sub.2) is sensitive to the comonomer
content of the measured polymer in solution and its response is
calibrated with known ethylene alpha-olefin copolymer
standards.
[0040] The detector when used with an ATREF instrument provides
both a concentration (CH.sub.2) and composition (CH.sub.3) signal
response of the eluted polymer during the TREF process. A polymer
specific calibration can be created by measuring the area ratio of
the CH.sub.3 to CH.sub.2 for polymers with known comonomer content
(preferably measured by NMR). The comonomer content of an ATREF
peak of a polymer can be estimated by applying the reference
calibration of the ratio of the areas for the individual CH.sub.3
and CH.sub.2 response (i.e. area ratio CH.sub.3/ CH.sub.2 versus
comonomer content).
[0041] The area of the peaks can be calculated using a full
width/half maximum (FWHM) calculation after applying the
appropriate baselines to integrate the individual signal responses
from the TREF chromatogram. The full width/half maximum calculation
is based on the ratio of methyl to methylene response area
[CH.sub.3/ CH2] from the ATREF infra-red detector, wherein the
tallest (highest) peak is identified from the base line, and then
the FWHM area is determined. For a distribution measured using an
ATREF peak, the FWHM area is defined as the area under the curve
between T1 and T2, where T1 and T2 are points determined, to the
left and right of the ATREF peak, by dividing the peak height by
two, and then drawing a line horizontal to the base line, that
intersects the left and right portions of the ATREF curve.
[0042] The application of infra-red spectroscopy to measure the
comonomer content of polymers in this ATREF-infra-red method is, in
principle, similar to that of GPC/FTIR systems as described in the
following references: Markovich, Ronald P.; Hazlitt, Lonnie G.;
Smith, Linley; "Development of gel-permeation
chromatography-Fourier transform infrared spectroscopy for
characterization of ethylene-based polyolefin copolymers".
Polymeric Materials Science and Engineering (1991), 65, 98-100.;
and Deslauriers, P. J.; Rohlfing, D. C.; Shieh, E. T.; "Quantifying
short chain branching microstructures in ethylene-1-olefin
copolymers using size exclusion chromatography and Fourier
transform infrared spectroscopy (SEC-FTIR)", Polymer (2002), 43,
59-170, both of which are incorporated by reference herein in their
entirety.
[0043] Nonwoven
[0044] In one aspect, the present invention is an extensible
nonwoven comprising a polyolefin elastomer fiber wherein the
surface of the fiber further comprises an inorganic filler or PDMS
or combinations thereof, wherein the inorganic filler, if present,
has D-90 particle size of 5 microns or less.
[0045] The nonwoven web of the present invention is comprised of
monocomponent or bicomponent fibers wherein the monocomponent or
bicomponent fibers comprise an elastomer. An elastomer is defined
to mean a polymer which has elastic properties. For purposes of the
present invention the term "elastic" is used herein to mean any
material which, upon application of a biasing force, is
stretchable, that is, elongatable, to a stretched, biased length
which is at least about 150 percent of its relaxed unbiased length,
and which will recover at least 50 percent of its elongation upon
release of the stretching, elongating force in less than one
minute. A hypothetical example would be a one (1) inch sample of a
material which is elongatable to at least 1.50 inches and which,
upon being elongated to 1.50 inches and released, will recover to a
length of not more than 1.25 inches in less than one minute. Many
elastic materials may be stretched by much more than 50 percent of
their relaxed length, for example, 80 percent or more, and many of
these will recover to substantially their original relaxed length,
for example, to within 105 percent of their original relaxed
length, upon release of the stretching force.
[0046] The fibers which make up the nonwoven web may be
monocomponent or bicomponent fibers. In either case, it is
preferred that the surface of the fiber comprise an elastomeric
material.
[0047] If bicomponent fibers are used, it is preferred that the
fibers be in a sheath-core form, with the sheath comprising an
elastomeric material. The core of such fibers may comprise
homopolymer polypropylene (hPP), polyester or an elastomeric
polymer. It is preferred that the sheath comprise from 10 to 50
percent by weight of the fiber.
[0048] It is also contemplated that the nonwoven web for uses in
the structure of the present invention may comprise bicomponent
staple fibers thermally bonded to a nonwoven web. The bicomponent
staple fibers can be in a sheath-core form, with the sheath
comprising an elastomeric material. The core of such fibers may
comprise homopolymer polypropylene (hPP), polyester or an
elastomeric polymer. It is preferred that the sheath comprise from
20 to 50 percent by weight of the fiber.
[0049] The fiber can be made from any polyolefin elastomer.
Preferred elastomers include LLDPE having a density less than 0.905
g/cc, PBPEs, and olefin block copolymers (OBC). Preferred
elastomeric LLDPEs are ethylene-octene copolymers having a density
between 0.86 and 0.905 g/cm.sup.3 and a melt index (MI, 2.16 kg @
190.degree. C.) between 2 to 25 g/10 min, preferably between 5 and
15 g/10 min
[0050] Preferred PBPEs are those comprising from 5 and 18% of units
derived from ethylene, preferably from 7 to 15%, more preferably
from 8 to 12%, and a melt flow rate (MFR, 2.16 kg @ 230.degree. C.)
of at least about 0.01, preferably at least about 0.05, more
preferably at least about 1 and most preferably at least about 10.
The maximum MFR typically does not exceed about 2,000, preferably
it does not exceed about 1000, more preferably it does not exceed
about 500, further more preferably it does not exceed about 80 and
most preferably it does not exceed about 50. Preferred PBPEs have a
relatively low crystallinity (or heat of fusion, AH), preferably in
the range of 0 to 80 J/g, preferably from 15 to 65 J/g, more
preferably from 30 to 60 J/g, a most preferably does not exceed
about 50 J/g as measured by DSC.
[0051] The weight average molecular weight (Mw) of the preferred
PBPEs of this invention can vary widely, but typically it is
between about 10,000 and 1,000,000 g/mol (with the understanding
that the only limit on the minimum or the maximum Mw is that set by
practical considerations). For copolymers used in the manufacture
of meltblown fibers, preferably the minimum Mw is about 20,000
g/mol, more preferably about 25,000 g/mol as measured by GPC.
[0052] The polydispersity of the copolymers of this invention is
typically between about 2 and about 4. "Narrow polydisperity",
"narrow molecular weight distribution", "narrow MWD" and similar
terms mean a ratio (Mw/Mn) of weight average molecular weight (Mw)
to number average molecular weight (Mn) of less than about 3.5,
preferably less than about 3.0, more preferably less than about
2.8, more preferably less than about 2.5, and most preferably less
than about 2.3. Polymers for use in fiber applications typically
have a narrow polydispersity. Blends comprising two or more of the
copolymers of this invention, or blends comprising at least one
copolymer of this invention and at least one other polymer, may
have a polydispersity greater than 4 although for spinning
considerations, the polydispersity of such blends is still
preferably between about 2 and about 4.
[0053] PBPEs are a relatively new class of propylene/alpha-olefin
copolymers which are further described in details in the U.S. Pat.
Nos. 6,960,635 and 6,525,157, incorporated herein by reference.
Such propylene/alpha-olefin copolymers are commercially available
from The Dow Chemical Company, under the tradename VERSIFY.TM., or
from ExxonMobil Chemical Company, under the tradename
VISTAMAXX.TM.. Other suitable propylene-based polymers included
TAFMER.TM. and NOTIO.TM. from Mitsui Chemicals Group and L-MODU.TM.
from Idemitsu Kosan.
[0054] Olefin block copolymers (OBC), are a relatively new class of
material which are more fully described in WO 2005/090427,
US2006/0199931, US2006/0199930, US2006/0199914, US2006/0199912,
US2006/0199911, US2006/0199910, US2006/0199908, US2006/0199907,
US2006/0199906, US2006/0199905, US2006/0199897, US2006/0199896,
US2006/0199887, US2006/0199884 (now U.S. Pat. No. 7,514,517),
US2006/0199872, US2006/0199744, US2006/0199030, US2006/0199006 and
US2006/0199983; each publication being fully incorporated herein by
reference. OBCs are commercially available from The Dow Chemical
Company under the INFUSE.TM. trademark.
[0055] The multi-block polymers typically comprise various amounts
of "hard" and "soft" segments. "Hard" segments refer to blocks of
polymerized units in which ethylene is present in an amount greater
than about 95 weight percent, and preferably greater than about 98
weight percent based on the weight of the polymer. In other words,
the comonomer content (content of monomers other than ethylene) in
the hard segments is less than about 5 weight percent, and
preferably less than about 2 weight percent based on the weight of
the polymer. In some embodiments, the hard segments comprise all or
substantially all ethylene. "Soft" segments, on the other hand,
refer to blocks of polymerized units in which the comonomer content
(content of monomers other than ethylene) is greater than about 5
weight percent, preferably greater than about 8 weight percent,
greater than about 10 weight percent, or greater than about 15
weight percent based on the weight of the polymer. In some
embodiments, the comonomer content in the soft segments can be
greater than about 20 weight percent, greater than about 25 weight
percent, greater than about 30 weight percent, greater than about
35 weight percent, greater than about 40 weight percent, greater
than about 45 weight percent, greater than about 50 weight percent,
or greater than about 60 weight percent.
[0056] The soft segments can often be present in a block
interpolymer from about 1 weight percent to about 99 weight percent
of the total weight of the block interpolymer, preferably from
about 5 weight percent to about 95 weight percent, from about 10
weight percent to about 90 weight percent, from about 15 weight
percent to about 85 weight percent, from about 20 weight percent to
about 80 weight percent, from about 25 weight percent to about 75
weight percent, from about 30 weight percent to about 70 weight
percent, from about 35 weight percent to about 65 weight percent,
from about 40 weight percent to about 60 weight percent, or from
about 45 weight percent to about 55 weight percent of the total
weight of the block interpolymer. Conversely, the hard segments can
be present in similar ranges.
[0057] The soft segment weight percentage and the hard segment
weight percentage can be calculated based on data obtained from DSC
or NMR as is generally known in the art, and referenced in U.S.
Pat. No. 7,514,517.
[0058] The term "crystalline" if employed, refers to a polymer that
possesses a first order transition or crystalline melting point
(Tm) as determined by differential scanning calorimetry (DSC) or
equivalent technique. The term may be used interchangeably with the
term "semicrystalline". The term "amorphous" refers to a polymer
lacking a crystalline melting point as determined by differential
scanning calorimetry (DSC) or equivalent technique.
[0059] The term "multi-block copolymer" or "segmented copolymer"
refers to a polymer comprising two or more chemically distinct
regions or segments (referred to as "blocks") preferably joined in
a linear manner, that is, a polymer comprising chemically
differentiated units which are joined end-to-end with respect to
polymerized ethylenic functionality, rather than in pendent or
grafted fashion. In a preferred embodiment, the blocks differ in
the amount or type of comonomer incorporated therein, the density,
the amount of crystallinity, the crystallite size attributable to a
polymer of such composition, the type or degree of tacticity
(isotactic or syndiotactic), regio-regularity or
regio-irregularity, the amount of branching, including long chain
branching or hyper-branching, the homogeneity, or any other
chemical or physical property. The multi-block copolymers are
characterized by unique distributions of both polydispersity index
(PDI or Mw/Mn), block length distribution, and/or block number
distribution due to the unique process making of the copolymers.
More specifically, when produced in a continuous process, the
polymers desirably possess PDI from 1.7 to 2.9, preferably from 1.8
to 2.5, more preferably from 1.8 to 2.2, and most preferably from
1.8 to 2.1. When produced in a batch or semi-batch process, the
polymers possess PDI from 1.0 to 2.9, preferably from 1.3 to 2.5,
more preferably from 1.4 to 2.0, and most preferably from 1.4 to
1.8.
[0060] In another aspect, the olefin block copolymers are
characterized by a .DELTA.T, in degree Celsius, defined as the
temperature for the tallest Differential Scanning Calorimetry
("DSC") peak minus the temperature for the tallest Crystallization
Analysis Fractionation ("CRYSTAF") peak and a heat of fusion in
J/g, .DELTA.H, and .DELTA.T and .DELTA.H satisfy the following
relationships:
.DELTA.T>-0.1299(.DELTA.H)+62.81, and preferably
.DELTA.T>-0.1299(.DELTA.H)+64.38, and more preferably
.DELTA.T>-0.1299(.DELTA.H)+65.95,
[0061] for .DELTA.H up to 130 J/g. Moreover, .DELTA.T is equal to
or greater than 48 .degree. C. for .DELTA.H greater than 130
J/g.
[0062] In yet another aspect, the olefin block copolymers have a
molecular fraction which elutes between 40.degree. C. and
130.degree. C. when fractionated using Temperature Rising Elution
Fractionation ("TREF'), characterized in that said fraction has a
molar comonomer content higher, preferably at least 5 percent
higher, more preferably at least 10 percent higher, than that of a
comparable random ethylene interpolymer fraction eluting between
the same temperatures, wherein the comparable random ethylene
interpolymer contains the same comonomer(s), and has a melt index,
density, and molar comonomer content (based on the whole polymer)
within 10 percent of that of the block interpolymer. Preferably,
the Mw/Mn of the comparable interpolymer is also within 10 percent
of that of the block interpolymer and/or the comparable
interpolymer has a total comonomer content within 10 weight percent
of that of the block interpolymer.
[0063] In still another aspect, the olefin block copolymers are
characterized by an elastic recovery, Re, in percent at 300 percent
strain and 1 cycle measured on a compression-molded film of an
ethylene/.alpha.-olefin interpolymer, and has a density, d, in
grams/cubic centimeter, wherein the numerical values of Re and d
satisfy the following relationship when ethylene/.alpha.-olefin
interpolymer is substantially free of a cross-linked phase:
Re>1481-1629(d); and preferably
Re>1491-1629(d); and more preferably
Re>1501-1629(d); and even more preferably
Re>1511-1629(d).
[0064] Comonomer content may be measured using any suitable
technique, with techniques based on nuclear magnetic resonance
("NMR'') spectroscopy preferred. Moreover, for polymers or blends
of polymers having relatively broad TREF curves, the polymer
desirably is first fractionated using TREF into fractions each
having an eluted temperature range of 10.degree. C. or less. That
is, each eluted fraction has a collection temperature window of
10.degree. C. or less. Using this technique, said block
interpolymers have at least one such fraction having a higher molar
comonomer content than a corresponding fraction of the comparable
interpolymer.
[0065] Preferably, for interpolymers of ethylene and 1-octene, the
block interpolymer has a comonomer content of the TREF fraction
eluting between 40 and 130.degree. C. greater than or equal to the
quantity (-0.2013) T+20.07, more preferably greater than or equal
to the quantity (-0.2013) T+21.07, where T is the numerical value
of the peak elution temperature of the TREF fraction being
compared, measured in .degree. C.
[0066] In still another aspect, the olefin block copolymer is
characterized by multiple blocks or segments of two or more
polymerized monomer units differing in chemical or physical
properties (blocked interpolymer), most preferably a multi-block
copolymer, said block interpolymer having a molecular fraction
which elutes between 40.degree. C. and 130.degree. C., when
fractionated using TREF increments, characterized in that every
fraction having a comonomer content of at least about 6 mole
percent, has a melting point greater than about 100.degree. C. For
those fractions having a comonomer content from about 3 mole
percent to about 6 mole percent, every fraction has a DSC melting
point of about 110.degree. C. or higher. More preferably, said
polymer fractions, having at least 1 mol percent comonomer, have a
DSC melting point that corresponds to the equation:
Tm>(-5.5926)(mol percent comonomer in the fraction)+135.90.
[0067] In yet another aspect, the olefin block copolymer is
characterized by multiple blocks or segments of two or more
polymerized monomer units differing in chemical or physical
properties (blocked interpolymer), most preferably a multi-block
copolymer, said block interpolymer having a molecular fraction
which elutes between 40.degree. C. and 130.degree. C., when
fractionated using TREF increments, characterized in that every
fraction that has an ATREF elution temperature greater than or
equal to about 76.degree. C., has a melt enthalpy (heat of fusion)
as measured by DSC, corresponding to the equation:
Heat of fusion in Joules per gram (J/gm)<(3.1718)(ATREF elution
temperature in Celsius)-136.58,
[0068] The block interpolymers for use in the present invention
have a molecular fraction which elutes between 40.degree. C. and
130.degree. C., when fractionated using TREF increments,
characterized in that every fraction that has an ATREF elution
temperature between 40.degree. C. and less than about 76.degree.
C., has a melt enthalpy (heat of fusion) as measured by DSC,
corresponding to the equation:
Heat of fusion (J/gm)<(1.1312)(ATREF elution temperature in
Celsius)+22.97.
[0069] In other embodiments, the inventive ethylene/.alpha.-olefin
interpolymer is characterized by an average block index, ABI, which
is greater than zero and up to about 1.0 and a molecular weight
distribution, Mw/Mn, greater than about 1.3. The average block
index, ABI, is the weight average of the block index ("BI") for
each of the polymer fractions obtained in preparative TREF from
20.degree. C. and 110.degree. C., with an increment of 5.degree. C.
:
[0070] where BIi is the block index for the ith fraction of the
inventive ethylene/.alpha.-olefin interpolymer obtained in
preparative TREF, and wi is the weight percentage of the ith
fraction.
[0071] For each polymer fraction, BI is defined by one of the two
following equations (both of which give the same BI value):
[0072] or
[0073] where TX is the preparative ATREF elution temperature for
the ith fraction (preferably expressed in Kelvin), PX is the
ethylene mole fraction for the ith fraction, which can be measured
by NMR or IR as described above. PAB is the ethylene mole fraction
of the whole ethylene/.alpha.-olefin interpolymer (before
fractionation), which also can be measured by NMR or IR. TA and PA
are the ATREF elution temperature and the ethylene mole fraction
for pure "hard segments" (which refer to the crystalline segments
of the interpolymer). As a first order approximation, the TA and PA
values are set to those for high density polyethylene homopolymer,
if the actual values for the "hard segments" are not available. For
calculations performed herein, TA is 372.degree. K, PA is 1.
[0074] TAB is the ATREF temperature for a random copolymer of the
same composition and having an ethylene mole fraction of PAB. TAB
can be calculated from the following equation:
Ln PAB=.alpha./TAB+.beta.
[0075] where .alpha. and .beta. are two constants which can be
determined by calibration using a number of known random ethylene
copolymers. It should be noted that .alpha. and .beta. may vary
from instrument to instrument. Moreover, one would need to create
their own calibration curve with the polymer composition of
interest and also in a similar molecular weight range as the
fractions. There is a slight molecular weight effect. If the
calibration curve is obtained from similar molecular weight ranges,
such effect would be essentially negligible. In some embodiments,
random ethylene copolymers satisfy the following relationship:
Ln P=-237.83/TATREF+0.639
[0076] TXO is the ATREF temperature for a random copolymer of the
same composition and having an ethylene mole fraction of PX. TXO
can be calculated from LnPX=.alpha./TXO+.beta.. Conversely, PXO is
the ethylene mole fraction for a random copolymer of the same
composition and having an ATREF temperature of TX, which can be
calculated from Ln PXO=.alpha./TX+.beta..
[0077] Once the block index (BI) for each preparative TREF fraction
is obtained, the weight average block index, ABI, for the whole
polymer can be calculated. In some embodiments, ABI is greater than
zero but less than about 0.3 or from about 0.1 to about 0.3. In
other embodiments, ABI is greater than about 0.3 and up to about
1.0. Preferably, ABI should be in the range of from about 0.4 to
about 0.7, from about 0.5 to about 0.7, or from about 0.6 to about
0.9. In some embodiments, ABI is in the range of from about 0.3 to
about 0.9, from about 0.3 to about 0.8, or from about 0.3 to about
0.7, from about 0.3 to about 0.6, from about 0.3 to about 0.5, or
from about 0.3 to about 0.4. In other embodiments, ABI is in the
range of from about 0.4 to about 1.0, from about 0.5 to about 1.0,
or from about 0.6 to about 1.0, from about 0.7 to about 1.0, from
about 0.8 to about 1.0, or from about 0.9 to about 1.0.
[0078] Preferred elastomers for the fiber surface are propylene
based plastomers or elastomers (PBPEs) and olefin block
copolymers.
[0079] Additive
[0080] The material which makes up the fiber, used in the
extensible nonwovens of the present invention further comprises an
inorganic filler or PDMS or combinations thereof. The inorganic
filler, if present, has D-90 particle size of 5 microns or less,
more preferably 2 microns or less. Any inorganic filler known in
the art can be used with this invention, however, for many
applications it is preferred that the filler be selected from the
group consisting of CaCO.sub.3, AlSiO.sub.3, talc, untreated or
treated fused silica and combinations thereof. The amount of
filler, when present, can vary depending on the type of filler used
as well as the form of the fiber (that is whether the fiber is a
monocomponent fiber or a bicomponent fiber). For monocomponent
fibers with CaCO.sub.3, it is generally preferred that the filler
be added in an amount of from 1-15% by weight the fiber, more
preferably from 5-8%. For bicomponent fibers with CaCO.sub.3, it is
generally preferred that the filler be added in an amount of from
5-50% by weight by weight of elastomeric materials used for the
surface of the fiber of the fiber, more preferably from 15-30%. For
monocomponent fibers with untreated fused silica, it is generally
preferred that the filler be added in an amount of from 0.25% to 5%
by weight the fiber, more preferably from 0.5-2%. For bicomponent
fibers with aluminum silicate, it is generally preferred that the
filler be added in an amount of from 5-30% by weight by weight of
elastomeric materials used for the surface of the fiber of the
fiber, more preferably from 15-20%. It is also contemplated that 2
or more fillers may be simultaneously used.
[0081] When polydimethylsiloxane (PDMS) is used, the PDMS used can
be a hydroxyl-terminated, ultra high molecular weight
poly(dimethylsiloxane) powder. The average particle size of the
PDMS powders is between 2 and 5 microns . The formulated PDMS
preferably has a molecular weight such that the material has a
viscosity greater than 15 million cSt.
[0082] The PDMS is conveniently added to the polymer composition in
the form of a masterbatch, in a polyethylene based carrier
material, in an amount so that the final composition used for the
material which will make up the surface of the fiber contains the
desired amount. For monocomponent fibers it is generally preferred
that the PDMS be added in an amount of from 0.05 to 1% by weight of
the fiber, preferably from 0.1 to 0.3%. For bicomponent fibers it
is preferred that the PDMS be added in an amount of from 0.5 to 10%
by weight of the material which makes up the surface of the fiber,
preferably from 1 to 2%.
[0083] The PDMS can be added to the polymer in any way known to the
art. The PDMS is ideally added prior to extrusion/fiber formation,
but may be added after fiber formation, for example as a coating.
Conveniently, the PDMS may be added to the polyolefin material via
a masterbatch with additional polyolefin material as the carrier
medium.
[0084] The PDMS may be used by itself or with one or more of the
inorganic fillers described above.
[0085] The nonwoven fabrics of the present invention can be
characterized in terms of a good balance of elongation, permanent
set, and bending modulus while exhibiting the improved hand-feel
characteristics.
EXAMPLES
[0086] The following resins are used to make a series of nonwoven
fabrics:
[0087] Resin A is an ethylene 1-octene block copolymer elastomer
having 15 g/10 min melt flow index (ASTM D1238, 190.degree. C.,
2.16 kg) and density of 0.866 g/cc (ASTM D792). The comonomer
(1-octene) content the resin is as follows: .about.18 mol. % in
soft segment and <1 mol. % in hard segment. The hard segment
content is .about.25 wt. %.
[0088] Resin B is a higher density linear low density polyethylene
having 17 g/10 min melt flow index (ASTM D1238, 190.degree. C.,
2.16 kg) and density of 0.955 g/cc (ASTM D792). The comonomer is
1-octene.
[0089] Several bico elastic/extensible nonwoven samples with
core/sheath ratio of 90/10 (by weight) and having different amounts
of additive C, D or E (as indicated below) in the sheath were
prepared to show the effect of additives on hand-feel perception
and mechanical properties of the elastic nonwovens. All samples are
fabricated on a Reicofil 3 pilot plant line. The processing
conditions and equipment details are summarized in Table 1, Table 2
and Table 3. The additives are described in Table 4. The fabricated
samples are shown in Table 5.
Comparative Eexample Ex 1
[0090] The core material was Resin A. The sheath material is 100%
Resin B. The bonding temperature is 100.degree. C.
Example 2
[0091] The core material is resin A and the sheath material was a
blend of 96 wt % of resin B (same resin as used in Comp. Ex. 1)
with 4 wt % masterbatch C and the bonding temperature is
100.degree. C.
Example 3
[0092] Example 2 is repeated except that the bonding temperature is
110.degree. C.
Example 4
[0093] Example 3 is repeated except that the sheath comprises 98 wt
% of resin B and 2 wt % of the additive Masterbatch C.
Example 5
[0094] Example 4 is repeated except that the bonding temperature is
100.degree. C.
Example 6
[0095] The core material is resin A, The sheath material was a
blend of 60 wt % resin B and 40 wt % of masterbatch D. The bonding
temperature was 100.degree. C.
Example 7
[0096] The core material is resin A, The sheath material was a
blend of 70 wt % resin B and 30 wt % of masterbatch E. The bonding
temperature was 95.degree. C.
Example 8
[0097] Example 7 is repeated except that the sheath comprises 40%
resin A and 60% masterbatch E.
Example 9
[0098] Example 8 is repeated except that the bonding temperature is
100.degree. C.
TABLE-US-00001 TABLE 1 Line details A1 Extruder A2 Extruder Type
Single screw, compression Single screw, barrier Diameter (mm) 100
80 Length (D) 25.5 30 Compression 3.75:1 --
TABLE-US-00002 TABLE 2 Spinnerete Length Type # of holes Hole
diameter (mm) L/D ratio (mm) BICO 5297 0.6 4 1200
TABLE-US-00003 TABLE 3 Processing conditions Output (kg/hour) 160
Quench air temperature (.degree. C.) 18-23 Cabine pressure (mbar)
20-15 Slot gap (mm) 18 Suction blower (%) 70 Temperature of the
spinneret 230-235 Bonding temperature (.degree. C.) 95, 100,
110
TABLE-US-00004 TABLE 4 Masterbatches Masterbatch Additive
Composition Comment Provided by MB C PDMS 40 of PDMSO Ultrahigh MW
Dow Corning (Polydimethylsiloxane) wt. % masterbatch in Resin B MB
D POLESTAR 400 40 wt. % of Al D90 = 1.5 .mu.m IMERYS (Al Silicate)
Silicate in Resin B MB E FiberLink 101S 50 wt.% Resin B D90 = 3.5
.mu.m IMERYS (CaCO.sub.3)
TABLE-US-00005 TABLE 5 Fabricated samples Additive in the Config-
Bonding Example sheath uration Core: Sheath: T, .degree. C. GSM
Comparative 0% BICO Resin RESIN B 100 20 Ex 1 90/10 A Ex 2 2% BICO
Resin RESIN B + 4% 100 20 PDMSO 90/10 A MB C Ex 3 2% BICO Resin
RESIN B + 4% 110 20 PDMSO 90/10 A MB C Ex 4 1% BICO Resin RESIN B +
2% 100 20 PDMSO 90/10 A MB C Ex 5 1% BICO Resin RESIN B + 2% 110 20
PDMSO 90/10 A MB C Ex 6 16% Al BICO Resin RESIN B + 40% 100 20
Silicate 90/10 A MB D Ex 7 15% BICO Resin RESIN B + 30% 95 20 CaCO3
90/10 A MB E Ex 8 30% BICO Resin RESIN B + 60% 95 20 CaCO3 90/10 A
MB E Ex 9 30% BICO Resin RESIN B + 60% 100 20 CaCO3 90/10 A MB
E
[0099] The tensile properties of the fabrics are measured using 5
cm wide strips with a 10 cm gauge length and a strain rate of
200%/min (20 cm/min) according to DIN 53857 (also labelled 42 ADC
Std Tensile)
[0100] Permanent set of the samples are measured according to the
same internal method; the data is being presented for comparative
purposes.
[0101] Frank bending of the fabricated samples is conducted
according to ASTM D747 standard.
[0102] Coefficient of friction (CoF) measurements of the nonwoven
samples are done according to ISO 8295/95 standard.
TABLE-US-00006 TABLE 6 Maximum force (CD/MD) (20 gsm samples)
Bonding MD CD T Fmax, N Force .sigma. Force .degree. C. GSM
Comparative Ex 1 3.4 0.15 2.1 0.33 100 20 Ex 2 3.3 0.14 1.8 0.16
100 20 Ex 3 3.0 0.17 1.8 0.11 110 20 Ex 4 3.5 0.41 2.2 0.31 100 20
Ex 5 3.2 0.1 1.9 0.24 110 20 Ex 6 4.2 0.44 2.4 0.23 100 20 Ex 7 5.2
0.42 3.0 0.2 95 20 Ex 8 3.8 0.14 2.5 0.1 95 20 Ex 9 5.1 0.26 2.8
0.24 100 20
TABLE-US-00007 TABLE 7 Elongation at F.sub.max (CD/MD) (20 gsm
samples) Bonding Elongation MD CD T at Fmax % .sigma. % .degree. C.
GSM Comparative Ex 1 145 9 197 30 100 20 Ex 2 145 12 187 24 100 20
Ex 3 110 8 170 16 110 20 Ex 4 150 23 210 33 100 20 Ex 5 120 6 172
33 110 20 Ex 6 130 11 182 21 100 20 Ex 7 175 14 220 23 95 20 Ex 8
140 8 200 9 95 20 Ex 9 200 6 220 16 100 20
TABLE-US-00008 TABLE 8 Permanent set (CD/MD) (20 gsm samples)
Bonding MD CD T Permanent set % .sigma. % .degree. C. GSM
Comparative Ex 1 36 1 42 2 100 20 Ex 2 37 2 44 1 100 20 Ex 3 39 1
42 2 110 20 Ex 4 34 4 43 1 100 20 Ex 5 41 1 43 1 110 20 Ex 6 32 1
40 1 100 20 Ex 7 32 1 35 2 95 20 Ex 8 31 1 37 3 95 20 Ex 9 30 1 34
2 100 20
TABLE-US-00009 TABLE 9 Frank bending (Fmax-CD/MD (70 gsm samples)
Bonding MD CD T Frank bending-Fmax N N .degree. C. GSM Comparative
Ex 1 11.7 8.5 100 20 Ex 2 5.6 4.0 100 20 Ex 3 7.2 4.4 110 20 Ex 4
7.1 5.5 100 20 Ex 5 8.4 6.5 110 20 Ex 6 8.3 5.8 100 20 Ex 7 7.6 5.5
95 20 Ex 8 8.2 6.4 95 20 Ex 9 7.3 6.4 100 20
TABLE-US-00010 TABLE 10 Coefficient of Friction (Outside/Metal and
Outside/Outside) (20 gsm samples) Bonding T CoF NW/NW NW/Metal
.degree. C. GSM Comparative Ex 1 1 1 100 20 Ex 2 0.38 0.76 100 20
Ex 3 0.43 0.67 110 20 Ex 4 0.46 0.72 100 20 Ex 5 0.58 0.88 110 20
Ex 6 0.7 0.34 100 20 Ex 7 0.7 0.46 95 20 Ex 8 0.81 0.57 95 20 Ex 9
0.77 0.57 100 20 (note that a value of `1` indicates that the
sample is completely blocked)
Sensory Panel--Attribute Waxy
[0103] The fabricated samples are submitted to a Sensory Science
Lab for smoothness, thermal, stiffness, tensile stretch (CD/MD) and
waxy analysis
[0104] Handfeel of nonwoven fabrics was evaluated by human sensory
panel. The panel consists of Dow employees who have been trained
for the sense of touch. The ranking method is used to evaluate
attributes.
[0105] Between 18 and 20 panelists were participated in each panel
session. Each attribute is analyzed using an F-statistic in
Analysis of Variance (ANOVA) to determine if there are any
significant differences among the samples in the multiple
comparisons. The F-ratio in the ANOVA indicates samples to be
significantly different, so a Fisher's Least Significant
[0106] Difference (LSD) is calculated to determine One-at-a-Time
multiple comparisons. The Fisher's LSD test is used for pairwise
comparisons when a significant F-value has been obtained
[0107] The bonded side of the nonwoven fabrics is evaluated.
Attribute Waxy
[0108] Technique: A sample is laid flat on the counter top. Each of
the panelist moves his/her finger across the surface of the sample
using the weight of his/her hand and forearm. [0109] Sample
preparations: The attribute is analyzed using a nonwoven fabric
sheet (21.times.14.5 cm.sup.2) [0110] Anchors/Controls for
attribute Waxy:
TABLE-US-00011 [0110] Waxy Rating Scale Value Fabric Type Source
2.0 AFFINITY .TM. LLDPE Produced by Dow Chemical non-woven 9.3
Filament nylon 6 Testfabrics ID #322 tricot-bright 13.0 100%
pre-shrunk cotton Hanes Her Way for Girls
TABLE-US-00012 TABLE 11 Samples used for sensory panel evaluation
Additive in Config- Bonding Example the sheath uration Core:
Sheath: T, .degree. C. GSM Comparative 0 % BICO Resin RESIN B 100
20 Ex 1 90/10 A Ex 2 2% BICO Resin RESIN B + 100 20 PDMSO 90/10 A
4% MB C Ex 4 1% BICO Resin RESIN B + 100 20 PDMSO 90/10 A 2% MB C
Ex 6 16% Al BICO Resin RESIN B + 100 20 Silicate 90/10 A 40% MB D
Ex 7 15% BICO Resin RESIN B + 95 20 CaCO3 90/10 A 30% MB E Ex 8 30%
BICO Resin RESIN B + 95 20 CaCO3 90/10 A 60% MB E Significantly
Different Sample Mean Group Than Sample Example 6 7.44 A
Comparative example, (16% Al Silicate) Example 7, Example 8 Example
4 (1% PDMS) 7.35 A B Comparative example, Example 7, Example 8
Example 2 (2% PDMS) 7.02 A B Comparative example, Example 7,
Example 8 Comparative example 5.93 C Example 7, Example 8 Example 7
(15% CaCO.sub.3) 4.87 D Example 7 Example 8 (30% CaCO.sub.3) 3.59
E
SEM analysis
[0111] NOVA Nansen 600--FEI with accelerating voltage of 3 kV). The
cross sectional cut of the fibers was done with a microtone
(ULTRACUT S FCS--REICHERT-LEICA) and specimens were stained with
RuO4 vapor. The results are shown in FIG. 1.
* * * * *
References