U.S. patent application number 15/779260 was filed with the patent office on 2018-12-13 for bicomponent filaments.
The applicant listed for this patent is DOW GLOBAL TECHNOLOGIES LLC. Invention is credited to Aleksandar Stoiljkovic.
Application Number | 20180355516 15/779260 |
Document ID | / |
Family ID | 57590826 |
Filed Date | 2018-12-13 |
United States Patent
Application |
20180355516 |
Kind Code |
A1 |
Stoiljkovic; Aleksandar |
December 13, 2018 |
BICOMPONENT FILAMENTS
Abstract
A bicomponent filament comprising a first region comprising an
ethylene-based polymer; a second region comprising a
propylene-based polymer; and a compatibilizer comprising a
crystalline block composite having (1) a crystalline ethylene-based
polymer (2) a crystalline alpha-olefin-based polymer, and (3) a
block copolymer having a crystalline ethylene block and a
crystalline alpha-olefin block, wherein the crystalline ethylene
block is essentially the same composition as the crystalline
ethylene-based polymer and the crystalline alpha-olefin block is
essentially the same composition as the crystalline
alpha-olefin-based polymer; wherein the compatibilizer is present
in at least one of the first region or the second region.
Inventors: |
Stoiljkovic; Aleksandar;
(Waedenswil, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DOW GLOBAL TECHNOLOGIES LLC |
Midland |
MI |
US |
|
|
Family ID: |
57590826 |
Appl. No.: |
15/779260 |
Filed: |
November 23, 2016 |
PCT Filed: |
November 23, 2016 |
PCT NO: |
PCT/US16/63497 |
371 Date: |
May 25, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62259806 |
Nov 25, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01F 8/06 20130101; C08L
2203/12 20130101; C08L 2205/08 20130101; D01D 5/34 20130101; C08L
23/04 20130101; C08L 2205/035 20130101; C08L 23/04 20130101; C08L
2205/03 20130101; D01F 1/10 20130101; C08L 53/00 20130101; C08L
23/10 20130101; C08L 23/10 20130101; C08L 23/04 20130101; D01F 6/46
20130101; C08L 23/04 20130101; C08L 53/00 20130101; C08L 23/10
20130101 |
International
Class: |
D01F 8/06 20060101
D01F008/06; D01F 6/46 20060101 D01F006/46 |
Claims
1. A bicomponent filament comprising: a first region comprising an
ethylene-based polymer; a second region comprising a
propylene-based polymer; and a compatibilizer comprising a
crystalline block composite having (1) a crystalline ethylene-based
polymer (2) a crystalline alpha-olefin-based polymer, and (3) a
block copolymer having a crystalline ethylene block and a
crystalline alpha-olefin block, wherein the crystalline ethylene
block is essentially the same composition as the crystalline
ethylene-based polymer and the crystalline alpha-olefin block is
essentially the same composition as the crystalline
alpha-olefin-based polymer; wherein the compatibilizer is present
in at least one of the first region or the second region.
2. The bicomponent filament of claim 1, wherein the crystalline
ethylene-based polymer has an ethylene content of greater than 90
mol. %.
3. The bicomponent filament of claim 1, wherein the crystalline
alpha-olefin-based polymer has greater than 90 mol. % units derived
from propylene and a comonomer selected from the group consisting
of C.sub.4-C.sub.10 alpha-olefins.
4. The bicomponent filament of claim 1, wherein the ethylene-based
polymer has a density of 0.920 to 0.965 g/cc and a melt index,
I.sub.2, of 0.5 to 150 g/10 minutes determined according to ASTM
D1238 at 190.degree. C. and 2.16 kg.
5. The bicomponent filament of claim 1, wherein the compatibilizer
is present only in the first region in an amount of from 1 wt. % to
less than 50 wt. %, based on the total weight of polymers present
in the first region.
6. The bicomponent filament of claim 1, wherein the compatibilizer
is present only in the second region in an amount of from 1 wt. %
to less than 50 wt. %, based on the total weight of polymers
present in the second region.
7. The bicomponent filament of claim 1, wherein the compatibilizer
is present in the first region and in the second region in an
amount of from 1 wt. % to less than 50 wt. %, based on the total
weight of polymers present in the first region and the second
region.
8. The bicomponent filament of claim 1, wherein the first region
and the second region are arranged in the form of a sheath/core,
tipped tri-lobal fibers, segmented cross, side-by-side, conjugate,
islands in the sea or a segmented pie.
9. The bicomponent filament of claim 1, wherein the first region is
a sheath of the bicomponent filament and the second region is a
core of the bicomponent filament.
10. The bicomponent filament of claim 9, wherein the core to sheath
weight ratio is 50:50 to 90:10.
11. A method of manufacturing a bicomponent filament, the method
comprising: blending a composition comprising an ethylene-based
polymer, a propylene-based polymer, and a compatibilizer, wherein
the compatibilizer comprises a crystalline block composite having
(1) a crystalline ethylene-based polymer (2) a crystalline
alpha-olefin based polymer, and (3) a block copolymer having a
crystalline ethylene block and a crystalline alpha-olefin block,
wherein the crystalline ethylene block is essentially the same
composition as the crystalline ethylene-based polymer and the
crystalline alpha-olefin block is essentially the same composition
as the crystalline alpha-olefin based polymer; and extruding the
composition to form a bicomponent filament; wherein the bicomponent
filament comprises a first region comprising the ethylene-based
polymer; a second region comprising the propylene-based polymer;
and the compatibilizer is present in at least one of the first
region or the second region.
12. A nonwoven fabric formed from the bicomponent filament of claim
1.
13. A method of manufacturing a nonwoven fabric, the method
comprising: providing two or more bicomponent filaments, each
bicomponent filament comprising a first region comprising an
ethylene-based polymer; a second region comprising a
propylene-based polymer; and a compatibilizer comprising a
crystalline block composite having (1) a crystalline ethylene-based
polymer (2) a crystalline alpha-olefin-based polymer, and (3) a
block copolymer having a crystalline ethylene block and a
crystalline alpha-olefin block, wherein the crystalline ethylene
block is essentially the same composition as the crystalline
ethylene-based polymer and the crystalline alpha-olefin block is
essentially the same composition as the crystalline
alpha-olefin-based polymer; wherein the compatibilizer is present
in at least one of the first region or the second region; and
bonding the two or more bicomponent filaments to each other to form
a nonwoven fabric.
Description
TECHNICAL FIELD
[0001] This disclosure relates to bicomponent filaments, and in
particular, to bicomponent filaments for use in nonwoven
fabrics.
BACKGROUND
[0002] Nonwoven fabrics (NW) are cloth-like materials that are
manufactured from filaments which are brought together via
different bonding techniques. Nonwoven fabrics may be used in
disposable absorbent articles, such as, diapers, wipes, feminine
hygiene, and adult incontinence products.
[0003] Nonwoven fabrics may comprise polypropylene (PP) because of
its excellent processing characteristics in spunmelt processes as
well as its contribution to the mechanical performance of the
product. One of the major drawbacks of nonwoven products that
contain polypropylene is the lack of softness. The softness can be
addressed by the introduction of polyethylene (PE) into the
nonwoven fabric. While the polyethylene can provide softness and
drapability, and the polypropylene can contribute to overall
mechanical performance, a decrease in nonwoven abrasion resistance
can occur, especially, as the fabric age.
[0004] It is therefore desirable to manufacture nonwoven fabrics
from polymeric blends of polyethylene and polypropylene having
improved abrasion resistance.
SUMMARY
[0005] Disclosed herein are bicomponent filaments. The bicomponent
filaments comprise a first region comprising an ethylene-based
polymer; a second region comprising a propylene-based polymer; and
a compatibilizer comprising a crystalline block composite having
(1) a crystalline ethylene-based polymer (2) a crystalline
alpha-olefin-based polymer, and (3) a block copolymer having a
crystalline ethylene block and a crystalline alpha-olefin block,
wherein the crystalline ethylene block is essentially the same
composition as the crystalline ethylene-based polymer and the
crystalline alpha-olefin block is essentially the same composition
as the crystalline alpha-olefin-based polymer; wherein the
compatibilizer is present in at least one of the first region or
the second region.
[0006] Also disclosed herein are methods of manufacturing
bicomponent filaments. The methods comprise blending a composition
comprising an ethylene-based polymer, a propylene-based polymer,
and a compatibilizer, wherein the compatibilizer comprises a
crystalline block composite having (1) a crystalline ethylene-based
polymer (2) a crystalline alpha-olefin based polymer, and (3) a
block copolymer having a crystalline ethylene block and a
crystalline alpha-olefin block, wherein the crystalline ethylene
block is essentially the same composition as the crystalline
ethylene-based polymer and the crystalline alpha-olefin block is
essentially the same composition as the crystalline alpha-olefin
based polymer; and extruding the composition to form a bicomponent
filament; wherein the bicomponent filament comprises a first region
comprising the ethylene-based polymer, a second region comprising
the propylene-based polymer, and the compatibilizer is present in
at least one of the first region or the second region.
[0007] Further disclosed herein are nonwoven fabrics. The nonwoven
fabrics are formed from a bicomponent filament comprising a first
region comprising an ethylene-based polymer; a second region
comprising a propylene-based polymer; and a compatibilizer
comprising a crystalline block composite having (1) a crystalline
ethylene-based polymer (2) a crystalline alpha-olefin-based
polymer, and (3) a block copolymer having a crystalline ethylene
block and a crystalline alpha-olefin block, wherein the crystalline
ethylene block is essentially the same composition as the
crystalline ethylene-based polymer and the crystalline alpha-olefin
block is essentially the same composition as the crystalline
alpha-olefin-based polymer; wherein the compatibilizer is present
in at least one of the first region or the second region.
[0008] Further disclosed herein are methods of manufacturing
nonwoven fabrics. The methods comprise providing two or more
bicomponent filaments, each bicomponent filament comprising a first
region comprising an ethylene-based polymer; a second region
comprising a propylene-based polymer; and a compatibilizer
comprising a crystalline block composite having (1) a crystalline
ethylene-based polymer (2) a crystalline alpha-olefin-based
polymer, and (3) a block copolymer having a crystalline ethylene
block and a crystalline alpha-olefin block, wherein the crystalline
ethylene block is essentially the same composition as the
crystalline ethylene-based polymer and the crystalline alpha-olefin
block is essentially the same composition as the crystalline
alpha-olefin-based polymer; wherein the compatibilizer is present
in at least one of the first region or the second region; and
bonding the two or more bicomponent filaments to each other to form
a nonwoven fabric.
[0009] Additional features and advantages of the embodiments will
be set forth in the detailed description which follows, and in part
will be readily apparent to those skilled in the art from that
description or recognized by practicing the embodiments described
herein, including the detailed description which follows, the
claims. It is to be understood that both the foregoing and the
following description describe various embodiments and are intended
to provide an overview or framework for understanding the nature
and character of the claimed subject matter, and serve to explain
the principles and operations of the claimed subject matter.
DETAILED DESCRIPTION
[0010] Reference will now be made in detail to embodiments of
bicomponent filaments, methods of manufacturing bicomponent
filaments, which may be used to produce nonwoven fabrics for use in
hygiene absorbent articles, such as, diapers, wipes, feminine
hygiene, and adult incontinence products. It is noted, however,
that this is merely an illustrative implementation of the
embodiments disclosed herein. The embodiments are applicable to
other technologies that are susceptible to similar problems as
those discussed above. For example, nonwoven fabrics comprising the
bicomponent filaments described herein may be used to produce face
masks, surgical gowns, isolation gowns, surgical drapes and covers,
surgical caps, tissues, bandages, and wound dressings are clearly
within the purview of the present embodiments. The terms "fibers"
and "filaments" are used interchangeably herein.
Bicomponent Filaments
[0011] In embodiments herein, the bicomponent filaments comprise a
first region comprising an ethylene-based polymer, a second region
comprising a propylene-based polymer, and a compatibilizer in at
least one of the first region or the second region.
First Region
[0012] The first region comprises an ethylene-based polymer. In
some embodiments herein, the first region of the bicomponent
filament may comprise from greater than 50 to 99, for example from
55 to 99, from 75 to 99, from 80 to 99, from 85 to 99, from 50 to
95, from 75 to 95, from 50 to 90, from 75 to 90, percent by weight,
of an ethylene-based polymer, based on the total amount of polymers
present in the first region.
[0013] The ethylene-based polymer comprises (a) less than or equal
to 100 percent, for example, at least 70 percent, or at least 80
percent, or at least 90 percent, or at least 92 percent, or at
least 95 percent, by weight of the units derived from ethylene; and
(b) less than 30 percent, for example, less than 25 percent, or
less than 20 percent, or less than 10 percent, or less than 8
percent, or less than 5 percent, by weight of units derived from
one or more alpha-olefin comonomers. As used herein, the term
"ethylene-based polymer" refers to a polymer that contains more
than 50 mole percent of polymerized ethylene monomer (based on the
total amount of polymerizable monomers) and, optionally, may
contain at least one comonomer.
[0014] In embodiments herein where the ethylene-based polymer
comprises at least one alpha-olefin comonomer, the alpha-olefin
comonomers have no more than 20 carbon atoms. For example, the
alpha-olefin comonomers may have 3 to 10 carbon atoms, or 3 to 8
carbon atoms. Exemplary alpha-olefin comonomers include, but are
not limited to, propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene.
The one or more alpha-olefin comonomers may, for example, be
selected from the group consisting of propylene, 1-butene,
1-hexene, and 1-octene; or in the alternative, from the group
consisting of 1-hexene and 1-octene. In embodiments herein, the
ethylene-based polymer may or may not be a homopolymer, copolymer,
or interpolymer.
[0015] The ethylene-based polymer can be made via gas-phase,
solution-phase, or slurry polymerization processes, or any
combination thereof, using any type of reactor or reactor
configuration known in the art, e.g., fluidized bed gas phase
reactors, loop reactors, stirred tank reactors, batch reactors in
parallel, series, and/or any combinations thereof. In some
embodiments, gas or solution reactors are used. Suitable
ethylene-based polymers may be produced according to the processes
described at pages 15-17 and 20-22 in WO 2005/111291 A1 or U.S.
2014/0248811, which are herein incorporated by reference. The
catalysts used to make the ethylene-based polymer described herein
may include Ziegler-Nana, metallocene, constrained geometry, single
site catalysts, or combinations thereof. For example, the
ethylene-based polymer may be a LLDPE, such as, a znLLDPE, which
refers to linear polyethylene made using Ziegler-Natta catalysts, a
uLLDPE or "ultra linear low density polyethylene," which may
include linear polyethylenes made using Ziegler-Natta catalysts, or
a mLLDPE, which refers to LLDPE made using metallocene or
constrained geometry catalyzed polyethylene. Examples of suitable
ethylene-based polymers may include ASPUN.TM. 6850 or ASPUN.TM.
6000, available from The Dow Chemical Company, 100-ZA25, available
from Ineos Olefins and Polymers Europe, and M200056, available from
Saudi Basic Industries Corporation, and MG9601S, available from
Borealis AG.
[0016] In some embodiments, the ethylene-based polymer is prepared
via a process comprising the steps of: (a) polymerizing ethylene
and optionally one or more a-olefins in the presence of a first
catalyst to form a semi-crystalline ethylene-based polymer in a
first reactor or a first part of a multi-part reactor; and (b)
reacting freshly supplied ethylene and optionally one or more
.alpha.-olefins in the presence of a second catalyst comprising an
organometallic catalyst thereby forming an ethylene-based polymer
composition in at least one other reactor or a later part of a
multi-part reactor. Additional exemplary solution and gas phase
polymerization processes may be found in U.S. 2014/024881, which is
herein incorporated by reference.
[0017] In embodiments herein, the ethylene-based polymer may have a
density of from 0.920-0.965 g/cc. All individual values and
subranges are included and disclosed herein. For example, in some
embodiments, the ethylene-based polymer may have a density of from
a lower limit of 0.920, 0.925, 0.930, or 0.935 g/cc to an upper
limit of 0.945, 0.950, 0.955, 0.960, or 0.965 g/cc. In one
exemplary embodiment, the ethylene-based polymer may have a density
of from 0.930-0.960 g/cc. In another exemplary embodiment, the
ethylene-based polymer may have a density of from 0.935-0.955
g/cc.
[0018] In embodiments herein, the ethylene-based polymer may have a
melt index, 12, of 0.5 to 150 g/10 minutes. All individual values
and subranges are included and disclosed herein. For example, in
some embodiments, the ethylene-based polymer may have a melt index,
I.sub.2, of from a lower limit of 1.0, 2.0, 4.0, 5.0, 7.5, 10.0,
12.0, 14.0, or 15.0 g/10 minutes to an upper limit of 20, 23, 25,
28, 30, 35, 40, 50, 75, 100, 125, or 150 g/10 minutes. In one
exemplary embodiment, the ethylene-based polymer may have a melt
index, 12, of 5 to 80 g/10 minutes, 5 to 50 g/10 minutes, or 10 to
50 g/10 minutes. In another exemplary embodiment, the
ethylene-based polymer may have a melt index, 12, of 5 to 35 g/10
minutes. In a further exemplary embodiment, the ethylene-based
polymer may have a melt index, 12, of 15 to 35 g/10 minutes.
[0019] In embodiments herein, the ethylene-based polymer may have a
molecular weight distribution (M.sub.w/M.sub.n) in the range of
from 2 to 4. All individual values and subranges are included and
disclosed herein. For example, in some embodiments, the
ethylene-based polymer may have a molecular weight distribution
(M.sub.w/M.sub.n) in the range of from 2.2 to 4, 2.5 to 4, 2.8 to
4, or 3 to 4.
[0020] The ethylene-based polymer may contain additives, such as,
antistatic agents, color enhancers, dyes, lubricants, fillers, such
as, TiO.sub.2 or CaCO.sub.3, opacifiers, nucleators, processing
aids, pigments, primary antioxidants, secondary antioxidants,
processing aids, UV stabilizers, anti-blocks, slip agents,
tackifiers, fire retardants, anti-microbial agents, odor reducer
agents, anti-fungal agents, and combinations thereof. The one or
more additives can be included in the ethylene-based polymer at
levels typically used in the art to achieve their desired purpose.
In some examples, the one or more additives are included in amounts
ranging from 0 to 10 wt % of the ethylene-based polymer, 0 to 5 wt
% of the ethylene-based polymer, 0.001 to 5 wt % of the
ethylene-based polymer, 0.001 to 3 wt % of the ethylene-based
polymer, 0.05 to 3 wt % of the ethylene-based polymer, or 0.05 to 2
wt % of the ethylene-based polymer.
Second Region
[0021] The first region comprises a propylene-based polymer. As
used herein, the term "propylene-based polymer" refers to a polymer
that contains more than 50 mole percent of polymerized propylene
monomer (based on the total amount of polymerizable monomers) and,
optionally, may contain at least one comonomer. In some embodiments
herein, the second region of the bicomponent filament may comprise
from greater than 50 to 99, for example from 55 to 99, from 75 to
99, from 80 to 99, from 85 to 99, from 50 to 95, from 75 to 95,
from 50 to 90, from 75 to 90, percent by weight, of an
propylene-based polymer, based on the total amount of polymers
present in the second region.
[0022] In embodiments herein, the propylene-based polymer is
propylene homopolymer, a propylene copolymer, or a combination
thereof. The polypropylene homopolymer may be isotactic, atactic,
or syndiotactic. In some embodiments, the propylene-based polymer
is an isotactic polypropylene homopolymer. In other embodiments,
the propylene-based polymer is a propylene/olefin copolymer. The
propylene/olefin copolymer may be random or block. The
propylene/olefin copolymer comprises (a) less than or equal to 100
percent, for example, at least 70 percent, or at least 80 percent,
or at least 90 percent, or at least 92 percent, or at least 95
percent, by weight of the units derived from propylene; and (b)
less than 30 percent, for example, less than 25 percent, or less
than 20 percent, or less than 10 percent, or less than 8 percent,
or less than 5 percent, by weight of units derived from one or more
alpha-olefin comonomers. In further embodiments, the
propylene-based polymer may be a combination of one or more
propylene homopolymers, one or more propylene copolymers, or a
combination of one or more propylene homopolymers and one or more
propylene copolymers.
[0023] In embodiments herein where the propylene-based polymer
comprises at least one alpha-olefin comonomer, the alpha-olefin
comonomers have no more than 20 carbon atoms. For example, the
alpha-olefin comonomers may have 3 to 10 carbon atoms, or 3 to 8
carbon atoms. Exemplary alpha-olefin comonomers include, but are
not limited to, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene,
1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or
more alpha-olefin comonomers may, for example, be selected from the
group consisting of ethylene, 1-butene, 1-hexene, and 1-octene; or
in the alternative, from the group consisting of ethylene. In
embodiments herein, the propylene-based polymer may or may not be a
homopolymer, copolymer, or interpolymer.
[0024] The propylene-based polymer can be made using any method for
polymerizing propylene and, optionally, one comonomer. For example,
gas phase, bulk or slurry phase, solution polymerization or any
combination thereof can be used. Polymerization can be a one stage
or a two or multistage polymerization process, carried out in at
least one polymerization reactor. For two or multistage processes
different combinations can be used, e.g. gas-gas phase,
slurry-slurry phase, slurry-gas phase processes. Suitable catalysts
can include Ziegler-Natta catalysts, a single-site catalyst
(metallocene or constrained geometry), or non-metallocene,
metal-centered, heteroaryl ligand catalysts, or combinations
thereof. Exemplary propylene-based polymers may include metallocene
polypropylenes, such as, ACHIEVE.TM. 3584, available from the Exxon
Mobil Corporation, and LUMICENE.TM. MR 2001, available from Total
Research & Technology Feluy; and Ziegler-Natta polypropylenes,
such as, HG475FB, available from Borealis AG, MOPLEN.TM. HP2814,
available from Lyondell Basell Industries Holdings, B.V., Sabic
518A, available from Saudi Basic Industries Corporation.
[0025] In embodiments herein, the propylene-based polymer has a
melt flow rate (MFR) from 5 to 100 g/10 min, as determined
according to ASTM D 1238 at 230.degree. C. and 2.16 kilograms. All
individual values and subranges from 0.5 g/10 min to 100 g/10 min
are included and disclosed herein. For example, in some
embodiments, the propylene-based polymer has a melt flow rate from
5 to 85 g/10 min, 10 to 80 g/10 min, from 10 to 75 g/10 min, from
10 to 50 g/10 min, from 15 to 45 g/10 min, or from 20 g/10 min to
40 g/10 min. In embodiments herein, the propylene-based polymer may
have a density of 0.900 to 0.910 g/cc, or from 0.900 to 0.905 g/cc.
The density may be determined according to ASTM D-792.
[0026] The propylene-based polymer may contain additives, such as,
antistatic agents, color enhancers, dyes, lubricants, fillers, such
as, TiO.sub.2 or CaCO.sub.3, opacifiers, nucleators, processing
aids, pigments, primary antioxidants, secondary antioxidants,
processing aids, UV stabilizers, anti-blocks, slip agents,
tackifiers, fire retardants, anti-microbial agents, odor reducer
agents, anti-fungal agents, and combinations thereof. The one or
more additives can be included in the propylene-based polymer at
levels typically used in the art to achieve their desired purpose.
In some examples, the one or more additives are included in amounts
ranging from 0 to 10 wt % of the propylene-based polymer, 0 to 5 wt
% of the propylene-based polymer, 0.001 to 5 wt % of the
propylene-based polymer, 0.001 to 3 wt % of the propylene-based
polymer, 0.05 to 3 wt % of the propylene-based polymer, or 0.05 to
2 wt % of the propylene-based polymer.
Compatibilizer
[0027] In embodiments herein, the first region and the second
region are compatibilized with each other by the use of a
compatibilizer. Without being bound by theory, it is believed that
due to incompatibility between polyethylene and polypropylene,
phase segregation can occur over time leading to delamination at
the polyethylene-polypropylene interface (i.e., the first
region-second region interface). In turn, this may result in
decreased nonwoven abrasion resistance. It is believed that use of
a compatibilizer in at least one of the first region or the second
region may reduce phase segregation over time at the
polyethylene-polypropylene interface (the first region-second
region interface), thereby leading to improved nonwoven abrasion
resistance. It is believed that the compatibilizer migrates to the
interface between the first region and the second region to bring
about compatibilization between the two regions.
[0028] In embodiments herein, the compatibilizer is a crystalline
block composite. The crystalline block composite has (1) a
crystalline ethylene-based polymer (CEP) (2) a crystalline
alpha-olefin-based polymer (CAOP), and (3) a block copolymer having
a crystalline ethylene block (CEB) and a crystalline alpha-olefin
block (CAOB), wherein the crystalline ethylene block is essentially
the same composition as the crystalline ethylene-based polymer and
the crystalline alpha-olefin block is essentially the same
composition as the crystalline alpha-olefin-based polymer. The
crystalline ethylene-based polymer (CEP) can have an ethylene
content of greater than 90 mol. %. The compositional split between
the amount of CEP and CAOP will be essentially the same as that
between the corresponding blocks in the block copolymer. The
alpha-olefin content of the CAOP and the CAOB may be greater than
90 mol %. In exemplary embodiments, the alpha-olefin is propylene.
For example, the CAOB and the CEB may be an iPP-EP (isotactic
polypropylene and ethylene-propylene) diblock copolymer.
[0029] The crystalline block composite (CBC) includes the
crystalline ethylene based polymer (CEP), the crystalline
alpha-olefin based polymer (CAOP), and the block copolymer having
the crystalline ethylene block (CEB) and the crystalline
alpha-olefin block (CAOB), where the CEB is essentially the same
composition as the CEP and the CAOB is essentially the same
composition as the CAOP. The alpha-olefin may be referred to as the
comonomer, and the amount of which accounts for a comonomer
content. In the crystalline block composite, the alpha-olefin is at
least one selected from the group of C.sub.3-10 .alpha.-olefins
(e.g., may be propylene and/or butylene). The CAOP and the CAOB may
have an alpha-olefin content that is greater than 90 mol %. The CEB
comprises greater than 90 mol % of units derived from ethylene
(i.e., ethylene content), and any remainder may be at least one
selected from the group of C.sub.3-10 .alpha.-olefins as a
comonomer (in an amount less than 10 mol %, less than 7 mol %, less
than 5 mol %, less than 3 mol %, and the like.).
[0030] In exemplary embodiments, the CAOP includes propylene, e.g.,
greater than 90 mol % units derived from propylene and any
remainder may be ethylene and/or at least one selected from the
group of C.sub.4-10 .alpha.-olefins as a comonomer (in an amount
less than 10 mol %, less than 7 mol %, less than 5 mol %, less than
4 mol %, less than 4 mol %, and the like.). When the CAOB includes
propylene, as does the CAOP, it may additionally comprise ethylene
as a comonomer. Further, the CEB and CEP may comprise propylene as
a comonomer. The compositional split between the amount of CEP and
CAOP will be essentially the same as that between the corresponding
blocks in the block copolymer. The CEB and the CAOB may be referred
to as hard (crystalline) segments/blocks.
[0031] In exemplary embodiments, the CAOB refers to highly
crystalline blocks of polymerized alpha olefin units in which the
monomer that is one of C.sub.3-10 .alpha.-olefins (such as
propylene) is present in an amount greater than 93 mol %, greater
than 95 mol %, and/or greater than 96 mol %. In other words, the
comonomer content (e.g., ethylene content) in the CAOBs is less
than less than 7 mol %, less than 5 mol %, and/or less than 4 mol
%. CAOBs with propylene crystallinity may have corresponding
melting points that are 80.degree. C. and above, 100.degree. C. and
above, 115.degree. C. and above, and/or 120.degree. C. and above.
In exemplary embodiments, CEB refers to blocks of polymerized
ethylene units in which the comonomer content (such as propylene)
is 7 mol % or less, between 0 mol % and 5 mol %, and/or between 0
mol % and 3 mol %. In exemplary embodiments, the CAOB comprise all
or substantially all propylene units. Such CEBs may have
corresponding melting points that are 75.degree. C. and above,
90.degree. C. and above, and/or 100.degree. C. and above.
[0032] In exemplary embodiments, the crystalline block composite
may have a total ethylene content that is from 40 wt % to 70 wt %
(e.g., 40 wt % to 65 wt %, 45 wt % to 65 wt %, 45 wt % to 60 wt %,
50 wt % to 55 wt %, and the like.), based on the total weight of
the crystalline block composite. The remainder of the total weight
of the crystalline block composite may be accounted for by units
derived from at least one C.sub.3-10 .alpha.-olefin (referring to a
comonomer content). For example, the remainder of the total weight
may be accounted for by units derived from propylene.
[0033] The crystalline block composite may include from 0.5 wt % to
95.0 wt % CEP, from 0.5 wt % to 95.0 wt % CAOP, and from 5.0 wt %
to 99.0 wt % of the crystalline block composite. For example, the
crystalline block composite may include from 5.0 wt % to 80.0 wt %
CEP, from 5.0 wt % to 80.0 wt % CAOP, and from 20.0 wt % to 90.0 wt
% of the crystalline block composite. Weight percents are based on
total weight of crystalline block composite. The sum of the weight
percents of CEP, CAOP, and the crystalline block composite equals
100%. An exemplary measurement of the relative amount of the
crystalline block composite is referred to as the Crystalline Block
Composite Index (CBCI), as discussed in U.S. Pat. Nos. 8,785,554,
8,822,598, and 8,822,599. The CBCI for the crystalline block
composite is greater than 0 and less than 1.0. For example, the
CBCI is from 0.20 to 0.99, from 0.30 to 0.99, from 0.40 to 0.99,
from 0.40 to 0.90, from 0.40 to 0.85, from 0.50 to 0.80, and/or
from 0.55 to 0.75.
[0034] The crystalline block composite may have, a T.sub.m greater
than 90.degree. C. (e.g., for both a first peak and a second peak),
a T.sub.m greater than 100.degree. C. (e.g., for both a first peak
and a second peak), and/or greater than 120.degree. C. (e.g., for
at least one of a first peak and a second peak). For example, the
T.sub.m is in the range of from 100.degree. C. to 250.degree. C.,
from 110.degree. C. to 220.degree. C., and/or from 115.degree. C.
to 220.degree. C. According to an exemplary embodiment, the
crystalline block composite exhibits a second peak T.sub.m in a
range from 100.degree. C. to 130.degree. C. (e.g., 100.degree. C.
to 120.degree. C., 100.degree. C. to 110.degree. C., and the like.)
and a first peak T.sub.m in a range from 110.degree. C. to
150.degree. C. (e.g., 110.degree. C. to 140.degree. C., 115.degree.
C. to 130.degree. C., 115.degree. C. to 125.degree. C., and the
like.), in which the second peak T.sub.m is less than the first
peak T.sub.m.
[0035] Crystalline block composites may be differentiated from
conventional, random copolymers, physical blends of polymers, and
block copolymers prepared via sequential monomer addition. The
crystalline block composites may be differentiated from random
copolymers and from a physical blend by characteristics such as
crystalline block composite index, better tensile strength,
improved fracture strength, finer morphology, improved optics,
and/or greater impact strength at lower temperature. The
crystalline block composites may be differentiated from block
copolymers prepared by sequential monomer addition by molecular
weight distribution, rheology, shear thinning, rheology ratio, and
block polydispersity. A unique feature of crystalline block
composites is that they cannot be fractionated by conventional
means by solvent or temperature such as xylene fractionation,
solvent/non-solvent, or temperature rising elution fractionation or
crystallization elution fractionation since the individual blocks
of the block copolymer are crystalline.
[0036] When produced in a continuous process, the crystalline block
composites desirably possess PDI from 1.7 to 15 (e.g., from 1.8 to
10, from 2.0 to 5, and/or from 2.5 to 4.8). Exemplary crystalline
block composites are described in, e.g., U.S. Patent Application
Publication Nos. 2011-0313106, 2011-0313107, and 2011-0313108, all
published on Dec. 22, 2011, which are incorporated herein by
reference with respect to descriptions of the crystalline block
composites, processes to make them, and methods of analyzing them.
In exemplary embodiments, the crystalline block composite may have
a molecular weight distribution (MWD), defined as weight average
molecular weight divided by number average molecular weight
(M.sub.w/M.sub.n) of 5.0 or less, from 3.0 to 4.8, and/or from 3.0
to 4.0.
[0037] The crystalline block composite polymers may be prepared by
a process comprising contacting an addition polymerizable monomer
or mixture of monomers under addition polymerization conditions
with a composition comprising at least one addition polymerization
catalyst, at least one cocatalyst, and a chain shuttling agent,
said process being characterized by formation of at least some of
the growing polymer chains under differentiated process conditions
in two or more reactors operating under steady state polymerization
conditions or in two or more zones of a reactor operating under
plug flow polymerization conditions. The term, "shuttling agent"
refers to a compound or mixture of compounds that is capable of
causing polymeryl exchange between at least two active catalyst
sites under the conditions of the polymerization. That is, transfer
of a polymer fragment occurs both to and from one or more of the
active catalyst sites. In contrast to a shuttling agent, a "chain
transfer agent" causes termination of polymer chain growth and
amounts to a one-time transfer of growing polymer from the catalyst
to the transfer agent. In a preferred embodiment, the block
composites and crystalline block composites comprise a fraction of
block polymer which possesses a most probable distribution of block
lengths.
[0038] Suitable processes useful in producing the crystalline block
composites may be found, e.g., in U.S. Patent Application
Publication No. 2008/0269412, published on Oct. 30, 2008. In
particular, the polymerization is desirably carried out as a
continuous polymerization, preferably a continuous, solution
polymerization, in which catalyst components, monomers, and
optionally solvent, adjuvants, scavengers, and polymerization aids
are continuously supplied to one or more reactors or zones and
polymer product continuously removed therefrom. Within the scope of
the terms "continuous" and "continuously" as used in this context
are those processes in which there are intermittent additions of
reactants and removal of products at small regular or irregular
intervals, so that, over time, the overall process is substantially
continuous. The chain shuttling agent(s) may be added at any point
during the polymerization including in the first reactor or zone,
at the exit or slightly before the exit of the first reactor, or
between the first reactor or zone and the second or any subsequent
reactor or zone. Due to the difference in monomers, temperatures,
pressures or other difference in polymerization conditions between
at least two of the reactors or zones connected in series, polymer
segments of differing composition such as comonomer content,
crystallinity, density, tacticity, regio-regularity, or other
chemical or physical difference, within the same molecule are
formed in the different reactors or zones. The size of each segment
or block is determined by continuous polymer reaction conditions,
and preferably is a most probable distribution of polymer
sizes.
[0039] For example, when producing a block copolymer having the
crystalline ethylene block (CEB) and the crystalline alpha-olefin
block (CAOB) in two reactors or zones it is possible to produce the
CEB in the first reactor or zone and the CAOB in the second reactor
or zone or to produce the CAOB in the first reactor or zone and the
CEB in the second reactor or zone. It may be more advantageous to
produce CEB in the first reactor or zone with fresh chain shuttling
agent added. The presence of increased levels of ethylene in the
reactor or zone producing CEB may lead to much higher molecular
weight in that reactor or zone than in the zone or reactor
producing CAOB. The fresh chain shuttling agent will reduce the MW
of polymer in the reactor or zone producing CEB thus leading to
better overall balance between the length of the CEB and CAOB
segments.
[0040] When operating reactors or zones in series it is necessary
to maintain diverse reaction conditions such that one reactor
produces CEB and the other reactor produces CAOB. Carryover of
ethylene from the first reactor to the second reactor (in series)
or from the second reactor back to the first reactor through a
solvent and monomer recycle system is preferably minimized. There
are many possible unit operations to remove this ethylene, but
because ethylene is more volatile than higher alpha olefins one
simple way is to remove much of the unreacted ethylene through a
flash step by reducing the pressure of the effluent of the reactor
producing CEB and flashing off the ethylene. A more preferable
approach is to avoid additional unit operations and to utilize the
much greater reactivity of ethylene versus higher alpha olefins
such that the conversion of ethylene across the CEB reactor
approaches 100%. With respect to the CAOB, the overall conversion
of monomers across the reactors may be controlled by maintaining
the alpha-olefin conversion at a high level (90 to 95%). Exemplary
catalysts and catalyst precursors for use to from the crystalline
block composite include metal complexes such as disclosed in
WO2005/090426.
[0041] The crystalline block composite may have a weight average
molecular weight (Mw) from 10,000 g/mol to 2,500,000 g/mol, from
35000 g/mol to 1,000,000 g/mol, from 50,000 g/mol to 300,000 g/mol,
and/or from 50,000 g/mol to 200,000 g/mol. For example, the Mw may
be from 20 kg/mol to 1000 kg/mol, from 50 kg/mol to 500 kg/mol,
and/or from 80 kg/mol to 125 kg/mol.
[0042] The MFR (melt flow rate) of the crystalline block composites
may be from 0.1 to 1000 dg/min (230.degree. C./2.16 kg), from 1 to
500 dg/min (230.degree. C./2.16 kg), from 5 to 100 g/10 min, from 5
to 50 g/10 min, or from 9 to 40 g/10 min at 230.degree. C. and 2.16
kg, when measured as per ASTM D 1238.
[0043] The compatibilizer may be present in at least one of the
first region or the second region. In some embodiments, the
compatibilizer is present only in the first region in an amount of
1 to less than 50 wt. %, 2 to 45 wt. %, 2 to 40 wt.5, 2 to 35 wt.
%, 2 to 30 wt. %, 5 to 35 wt. %, 5 to 30 wt. %, 5 to 25 wt. %, or 5
to 20 wt. %, based on the total weight of polymers present in the
first region. In other embodiments, the compatibilizer may be
present only in the second region in an amount of from 1 wt. % to
less than 50 wt. %, 2 to 45 wt. %, 2 to 40 wt.5, 2 to 35 wt. %, 2
to 30 wt. %, 5 to 35 wt. %, 5 to 30 wt. %, 5 to 25 wt. %, or 5 to
20 wt. %, based on the total weight of polymers present in the
second region. In further embodiments, the compatibilizer may be
simultaneously present in the first region and in the second region
in an amount of from 1 wt. % to less than 50 wt. %, 2 to 45 wt. %,
2 to 40 wt.5, 2 to 35 wt. %, 2 to 30 wt. %, 5 to 35 wt. %, 5 to 30
wt. %, 5 to 25 wt. %, or 5 to 20 wt. %, based on the total weight
of polymers present in the first region and the second region.
Bicomponent Filaments & Nonwoven Fabrics
[0044] Bicomponent filaments described herein may be produced by
melt spinning processes that include staple fiber spinning
(including short spinning, and long spinning). In some embodiments,
the bicomponent filaments may be made by blending a composition
comprising an ethylene-based polymer, a propylene-based polymer,
and a compatibilizer, and extruding the composition to form a
bicomponent filament, wherein the bicomponent filament comprises a
first region comprising the ethylene-based polymer, a second region
comprising the propylene-based polymer, and the compatibilizer is
present in at least one of the first region or the second region.
The ethylene-based polymer, propylene-based polymer, and
compatibilizer have been previously described herein.
[0045] The resulting cross-section of the bicomponent filament may
resemble a variety of different configurations. For example, the
first region and the second region of the bicomponent filament may
be arranged in the form of a sheath/core, tipped tri-lobal fibers,
segmented cross, side-by-side, conjugate, islands in the sea, or a
segmented pie. In some embodiments, the first region and the second
region of the bicomponent filament may be arranged in the form of a
sheath/core, tipped tri-lobal fibers, segmented cross,
side-by-side, conjugate, islands in the sea, or a segmented pie,
and at least one outer surface of the bicomponent filament
comprises an ethylene-based polymer blended with the crystalline
block composite compatibilizer.
[0046] In some embodiments, the first region and the second region
of the bicomponent filament may have a sheath-core structure,
respectively. The sheath layer is disposed on the core and
surrounds the circumferential surface of the core. The core to
sheath weight ratio may range from 50:50 to 90:10, 60:40 to 90:10,
or 65:35 to 90:10. The use of an ethylene-based polymer in the
sheath can improve the softness or haptics of a nonwoven fabric.
Conversely, nonwoven fabric comprising filaments made only from
higher modulus polymers, such as, a polypropylene homopolymer, can
provide different haptics and are often considered less soft.
However, fabrics comprised of ethylene-based polymers in the sheath
can suffer from reduced resistance to abrasion compared to fabrics
made from only polypropylene. While haptics are not easily
quantified, they can be evaluated using sensory panels. Sensory
panelists can be asked to rank various samples according to
attributes such as "smoothness"; "cloth-like"; "stiffness" and
"noise intensity". A more objective test involves the use of a
commercially available device known as "Handle-O-Meter". The
"Handle-O-Meter" is a commercially available apparatus from the
Thwing-Albert Company.
[0047] The bicomponent filaments described herein may be used to
form nonwoven fabrics. Nonwoven fabrics can be manufactured by
various methods generally known in the art, examples of which are
described in, for example, "Introduction to Nonwoven Technologies"
by Batra, Subhash and Pourdeyhimi, Bahnam, 2012, and "Polyolefin
Fibres: Industrial and Medical Applications," S. C. O. Ugbolue,
2009. As used herein, the term "nonwoven web" or "nonwoven fabric"
or "nonwoven", refers to a web that has a structure of individual
fibers or filaments, which are interlaid, but not in any regular,
repeating manner.
[0048] The nonwoven web may comprise a single web, such as, a
spunbond web, a carded web, an airlaid web, a spunlaced web, or a
meltblown web. "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 to that
of 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. "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.
[0049] Because of the relative strengths and weaknesses associated
with the different processes and materials used to make nonwoven
fabrics, composite structures of more than one layer are often used
in order to achieve a better balance of properties. Such structures
are often identified by letters designating the various lays such
as SM for a two layer structure consisting of a spunbond layer and
a meltblown layer, SMS for a three layer structure, or more
generically S.sub.nX.sub.nS.sub.n structures, where "X" can be
independently a spunbond layer, a carded layer, an airlaid layer, a
spunlaced layer, or a meltblown layer and "n" can be any number,
although for practical purposes is generally less than 5. In order
to maintain structural integrity of such composite structures, the
layers must be bonded together. Common methods of bonding include
thermal calendar point bonding, adhesive lamination, ultrasonic
bonding, and other methods known to those skilled in the art. All
of these structures may be used in the present invention.
[0050] In some embodiments, where the nonwoven may comprise
bicomponent filaments having a core/sheath configuration, and where
the propylene-based polymers used in the core have a higher melting
point than the ethylene-based polymers used in the sheath, the
sheath may provide a lower bonding temperature for the nonwoven in
thermal calendaring operations. The sheath may also provide other
properties to the nonwoven, such as, softness or certain haptic
properties, while the core layer may provide other properties, such
as, tensile strength. In addition, since the propylene-based
polymers used in the core have a higher melting point than the
ethylene-based polymers used in the sheath layer, the
propylene-based polymers used in the core do not completely
melt/flow and can provide a level of integrity and strength to the
nonwoven.
[0051] In some embodiments, the nonwovens can also be laminates
such as spunbond layers and some meltblown layers, such as a
spunbond/meltblown/spunbond (SMS) laminate and others as disclosed
in U.S. Pat. No. 4,041,203 to Brock et al., U.S. Pat. No. 5,169,706
to Collier, et al., U.S. Pat. No. 5,145,727 to Potts et al., U.S.
Pat. No. 5,178,931 to Perkins et al., and U.S. Pat. No. 5,188,885
to Timmons et al., each incorporated by reference in their
entirety. The nonwoven may be an elastic nonwoven comprised of
elastic materials or an extensible nonwoven, such as, spunlaced
materials which are hydroentangled spun-melt nonwovens. The
nonwoven may be inelastic, but elongatable or extensible. Such
inelastic nonwovens may be used in elastic laminates by bonding
them to the elastic film while the elastic film is in a stretched
condition so that when the elastic film is allowed to retract the
nonwoven gathers or puckers between the portions where the nonwoven
is bonded to the elastic film creating corrugations in the
nonwovens. This live stretch process of lamination is described in
U.S. Pat. No. 4,720,415. Other means of corrugating nonwovens are
available commercially, such as those supplied by Micrex.
Extensible, but inelastic nonwovens can also be used in elastic
laminates through a process described as incremental stretching. In
these processes, the elastic film and extensible but non-elastic
nonwoven are joined in the unstretched state. The laminate is then
subjected to stretching or tension as described in U.S. Pat. Nos.
5,167,897, 4,107,364, 4,209,463, and 4,525,407. When the tension is
released on the web the nonwoven is permanently deformed in the
areas where it was stretched and does not go back to its original
shape so that the elastic laminate is now able to stretch and
recover without significant constraint from the nonwoven in the
areas where it has been pre-stretched.
[0052] In some embodiments, a laminate having an SMS
structure--i.e., a meltblown nonwoven fabric layer disposed between
two spunbond nonwoven fabric layers may be manufactured for use in
a variety of different articles. The spunbond nonwoven fabric
comprises bicomponent filaments as described herein, while the
meltblown nonwoven fabric comprises monocomponent fibers that may
comprise propylene-based polymers. The presence of the
compatibilizer in the fibers of the spunbond layer may facilitate
adhesion with the propylene-based polymer in the meltblown layer to
produce a unique product having a synergistic combination of
tensile strength, softness, and barrier properties.
[0053] The combination of spunbond and meltblown layers in a
laminate can facilitate improved barrier properties, which is
important for applications, such as, leg cuffs in hygiene absorbent
products, e.g., diapers, training pants, or adult incontinence
products, medical drapes and gowns, or face masks. The presence of
an ethylene-based polymer in the sheath improves the softness or
haptics of the non-woven laminate and the presence of the
compatibilizer in the sheath or in the sheath and core enables
improved abrasion resistance of the spunbond non-woven. SMS
laminates manufactured in this manner display an optimal
combination of softness, barrier properties, abrasion resistance
and laminate tensile strength. A plurality of spunbond and
meltblown layers may be bonded in this manner. In other words, a
laminate having a structure of (SM).sub.x, where x can be any
integer greater than or equal to 2 may be manufactured for use. The
laminate structure may be made by depositing a nonwoven fabrics in
series: first depositing a spunbond fabric onto a conveyor belt,
followed by a meltblown fabric, and then another spunbond fabric.
The layers may be bonded to one another through a variety of means
including thermal calendar bonding or ultrasonic bonding.
Test Methods
[0054] A discussion of the methods used herein may also be found
in, e.g., U.S. Pat. No. 8,822,599, which is herein incorporated by
reference. Test methods include the following:
Density
[0055] Samples are prepared according to ASTM D-1928. Measurements
are made within one hour of sample pressing using ASTM D-792,
Method B.
Melt Index
[0056] Melt index, or I.sub.2, is measured in accordance with
ASTM-D 1238, condition 190.degree. C./2.16 kg, and is reported in
grams eluted per 10 minutes.
Melt Flow Rate
[0057] Melt Flow Rate (MFR) is measured according to ASTM-D1238,
condition 230.degree. C./2.16 kg. The result is reported in
grams/10 minutes.
Tensile Testing
[0058] Tensile testing (including Elongation at Break in the
machine direction (MD) and cross direction (CD) and Tensile
Strength in the machine direction (MD) and cross direction (CD)) is
performed according to DIN EN ISO 29073: 1992-08.
[0059] High Temperature Liquid Chromatography (HTLC)
[0060] HTLC is performed according to the methods disclosed in US
Patent Application Publication No. 2010-0093964 and U.S. patent
application Ser. No. 12/643,111, filed Dec. 21, 2009, both of which
are herein incorporated by reference. Samples are analyzed by the
methodology described below.
[0061] A Waters GPCV2000 high temperature SEC chromatograph was
reconfigured to build the HT-2DLC instrumentation. Two Shimadzu
LC-20AD pumps were connected to the injector valve in GPCV2000
through a binary mixer. The first dimension (D1) HPLC column was
connected between the injector and a 10-port switch valve (Valco
Inc). The second dimension (D2) SEC column was connected between
the 10-port valve and LS (Varian Inc.), IR (concentration and
composition), RI (refractive index), and IV (intrinsic viscosity)
detectors. RI and IV were built-in detector in GPCV2000. The IRS
detector was provided by PolymerChar, Valencia, Spain.
[0062] Columns:
[0063] The D1 column was a high temperature Hypercarb graphite
column (2.1.times.100 mm) purchased from Thermo Scientific. The D2
column was a PLRapid-H column purchased from Varian (10.times.100
mm).
[0064] Reagents:
[0065] HPLC grade trichlorobenzene (TCB) was purchased from Fisher
Scientific. 1-Decanol and decane were from Aldrich.
2,6-Di-tert-butyl-4-methylphenol (Ionol) was also purchased from
Aldrich.
[0066] Sample Preparation:
[0067] 0.01-0.15 g of polyolefin sample was placed in a 10-mL
Waters autosampler vial. 7-mL of either 1-decanol or decane with
200 ppm Ionol was added to the vial afterwards. After sparging
helium to the sample vial for about 1 min, the sample vial was put
on a heated shaker with temperature set at 160.degree. C. The
dissolution was done by shaking the vial at the temperature for 2
hr. The vial was then transferred to the autosampler for injection.
Please note that the actual volume of the solution was more than 7
mL due to the thermal expansion of the solvent.
[0068] HT-2DLC:
[0069] The D1 flow rate was at 0.01 mL/min. The composition of the
mobile phase was 100% of the weak eluent (1-decanol or decane) for
the first 10 min of the run. The composition was then increased to
60% of strong eluent (TCB) in 489 min. The data were collected for
489 min as the duration of the raw chromatogram. The 10-port valve
switched every three minutes yielding 489/3=163 SEC chromatograms.
A post-run gradient was used after the 489 min data acquisition
time to clean and equilibrate the column for the next run:
[0070] Clean Step:
490 min: flow=0.01 min; // Maintain the constant flow rate of 0.01
mL/min from 0-490 min. 491 min: flow=0.20 min; // Increase the flow
rate to 0.20 mL/min. 492 min: % B=100; // Increase the mobile phase
composition to 100% TCB 502 min: % B=100; // Wash the column using
2 mL of TCB
[0071] Equilibrium Step:
503 min: % B=0; // Change the mobile phase composition to 100% of
1-decanol or decane 513 min: % B=0; // Equilibrate the column using
2 mL of weak eluent 514 min: flow=0.2 mL/min; // Maintain the
constant flow of 0.2 mL/min from 491-514 min 515 min: flow=0.01
mL/min; // Lower the flow rate to 0.01 mL/min.
[0072] After step 8, the flow rate and mobile phase composition
were the same as the initial conditions of the run gradient. The D2
flow rate was at 2.51 mL/min. Two 60 .mu.L loops were installed on
the 10-port switch valve. 30-.mu.L of the eluent from D1 column was
loaded onto the SEC column with every switch of the valve.
[0073] The IR, LS15 (light scattering signal at 15.degree.), LS90
(light scattering signal at) 90.degree., and IV (intrinsic
viscosity) signals were collected by EZChrom through a SS420X
analogue-to-digital conversion box. The chromatograms were exported
in ASCII format and imported into a home-written MATLAB software
for data reduction. Using an appropriate calibration curve of
polymer composition and retention volume, of polymers that are of
similar nature of the CAOB and CEB polymers being analyzed.
Calibration polymers should be narrow in composition (both
molecular weight and chemical composition) and span a reasonable
molecular weight range to cover the composition of interest during
the analysis. Analysis of the raw data was calculated as follows,
the first dimension HPLC chromatogram was reconstructed by plotting
the IR signal of every cut (from total IR SEC chromatogram of the
cut) as a function of the elution volume. The IR vs. D1 elution
volume was normalized by total IR signal to obtain weight fraction
vs. D1 elution volume plot. The IR methyl/measure ratio was
obtained from the reconstructed IR measure and IR methyl
chromatograms. The ratio was converted to composition using a
calibration curve of PP wt. % (by NMR) vs. methyl/measure obtained
from SEC experiments. The MW was obtained from the reconstructed IR
measure and LS chromatograms. The ratio was converted to MW after
calibration of both IR and LS detectors using a PE standard.
Differential Scanning Calorimetry (DSC)
[0074] Differential Scanning calorimetry is performed on a TA
Instruments Q1000 DSC equipped with an RCS cooling accessory and an
auto sampler. A nitrogen purge gas flow of 50 ml/min is used. The
sample is pressed into a thin film and melted in the press at about
230.degree. C. and then air-cooled to room temperature (25.degree.
C.). About 3-10 mg of material is then cut, accurately weighed, and
placed in a light aluminum pan (ca 50 mg) which is later crimped
shut. The thermal behavior of the sample is investigated with the
following temperature profile: the sample is rapidly heated to
230.degree. C. and held isothermal for 3 minutes in order to remove
any previous thermal history. The sample is then cooled to
-90.degree. C. at 10.degree. C./min cooling rate and held at
-90.degree. C. for 3 minutes. The sample is then heated to
230.degree. C. at 10.degree. C./min heating rate. The cooling and
second heating curves are recorded.
.sup.13C Nuclear Magnetic Resonance (NMR)
[0075] Sample Preparation--The samples are prepared by adding
approximately 2.7 g of a 50/50 mixture of
tetrachloroethane-d2/orthodichlorobenzene that is 0.025M in
chromium acetylacetonate (relaxation agent) to 0.21 g sample in a
10 mm NMR tube. The samples are dissolved and homogenized by
heating the tube and its contents to 150.degree. C.
[0076] Data Acquisition Parameters--The data is collected using a
Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL
high-temperature CryoProbe. The data is acquired using 320
transients per data file, a 7.3 sec pulse repetition delay (6 sec
delay+1.3 sec acq. time), 90 degree flip angles, and inverse gated
decoupling with a sample temperature of 125.degree. C. All
measurements are made on non spinning samples in locked mode.
Samples are homogenized immediately prior to insertion into the
heated (130.degree. C.) NMR Sample changer, and are allowed to
thermally equilibrate in the probe for 15 minutes prior to data
acquisition. Comonomer content in the crystalline block composite
polymers is measurable using this technique.
Gel Permeation Chromatography (GPC)
[0077] The gel permeation chromatographic system consists of either
a Polymer Laboratories Model PL-210 or a Polymer Laboratories Model
PL-220 instrument. The column and carousel compartments are
operated at 140.degree. C. Three Polymer Laboratories 10-micron
Mixed-B columns are used. The solvent is 1,2,4 trichlorobenzene.
The samples are prepared at a concentration of 0.1 grams of polymer
in 50 milliliters of solvent containing 200 ppm of butylated
hydroxytoluene (BHT). Samples are prepared by agitating lightly for
2 hours at 160.degree. C. The injection volume used is 100
microliters and the flow rate is 1.0 ml/minute.
[0078] Calibration of the GPC column set is performed with 21
narrow molecular weight distribution polystyrene standards with
molecular weights ranging from 580 to 8,400,000, arranged in 6
"cocktail" mixtures with at least a decade of separation between
individual molecular weights. The standards are purchased from
Polymer Laboratories (Shropshire, UK). The polystyrene standards
are prepared at 0.025 grams in 50 milliliters of solvent for
molecular weights equal to or greater than 1,000,000, and 0.05
grams in 50 milliliters of solvent for molecular weights less than
1,000,000. The polystyrene standards are dissolved at 80.degree. C.
with gentle agitation for 30 minutes. The narrow standards mixtures
are run first and in order of decreasing highest molecular weight
component to minimize degradation. The polystyrene standard peak
molecular weights are converted to polyethylene molecular weights
using the following equation (as described in Williams and Ward, J.
Polym. Sci., Polym. Let., 6, 621 (1968)):
M.sub.polypropylene=0.645(M.sub.polystyrene).
[0079] Polypropylene equivalent molecular weight calculations are
performed using Viscotek TriSEC software Version 3.0.
Fuzz Level
[0080] Fuzz level is determined on a Sutherland 2000 Ink Rub
Tester. An 11.0 cm.times.4.0 cm piece of nonwoven is abraded with
sandpaper according to ISO POR 01 106 (a cloth sandpaper aluminum
oxide 320-grit is affixed to a 2 lb. weight, and rubbed for 20
cycles at a rate of 42 cycles per minute) so that loose fibers are
accumulated on the top of the laminate. The loose fibers are
collected using tape and measured gravimetrically. The fuzz level
is then determined as the total weight of loose fiber in grams
divided by the laminate specimen surface area (44.0 cm.sup.2).
Examples
[0081] These examples were conducted to demonstrate the preparation
of bicomponent filaments that can be used in the manufacture of
nonwovens. The bicomponent filaments have an ethylene-based polymer
sheath layer disposed on a core that contains a propylene-based
polymer.
Preparation of Crystalline Block Composite
[0082] The Crystalline Block Composites (CBC1 and CBC2) are
prepared using two continuous stirred tank reactors (CSTR)
connected in series. The first reactor is approximately 12 gallons
in volume while the second reactor is approximately 26 gallons.
Each reactor is hydraulically full and set to operate at steady
state conditions. Monomers, Solvent, Catalyst, Cocatalyst-1,
Cocatalyst-2, and CSA-1 are flowed to the first reactor according
to the process conditions outlined in Table 1. Then, the first
reactor contents, as described in Table 1, below, are flowed to a
second reactor in series. Additional Catalyst, Cocatalyst-1, and
Cocatalyst-2 are added to the second reactor. Table 2, below, shows
the analytical characteristics of the CBC's.
[0083] In particular, Catalyst-1
([[rel-2',2'''-[(1R,2R)-1,2-cylcohexanediylbis(methyleneoxy-.kappa.O)]
bis[3-(9H-carbazol-9-yl)-5-methyl[1,1'-biphenyl]-2-olato-.kappa.O]](2-)]d-
imethyl-hafnium) and Cocatalyst-1, a mixture of
methyldi(C.sub.14-18 alkyl)ammonium salts of
tetrakis(pentafluorophenyl)borate, prepared by reaction of a long
chain trialkylamine (Armeen.TM. M2HT, available from Akzo-Nobel,
Inc.), HCl and Li[B(C.sub.6F.sub.5).sub.4], substantially as
disclosed in U.S. Pat. No. 5,919,983, Ex. 2., are purchased from
Boulder Scientific and used without further purification. CSA-1
(diethylzinc or DEZ) and cocatalyst-2 (modified methylalumoxane
(MMAO)) are purchased from Akzo Nobel and used without further
purification.
[0084] The Solvent for the polymerization reaction is a hydrocarbon
mixture (ISOPAR.RTM.E) obtainable from ExxonMobil Chemical Company
and purified through beds of 13-X molecular sieves prior to use.
Referring to Table 1, the process conditions for producing the CBC2
are shown.
TABLE-US-00001 TABLE 1 Reactor Conditions Material CBC2 Reactor 1st
Reactor 2nd Reactor Reactor Control Temp. (.degree. C.) 153 136
Solvent Feed (lb/hr) 441 376 Propylene Feed (lb/hr) 6.9 77.0
Ethylene Feed (lb/hr) 70.6 0 Hydrogen Feed SCCM) 0 0 Reactor
Ethylene Conc. (g/L) 1.68 0.02 Reactor Propylene Conc. (g/L) 0.34
2.95 Catalyst Efficiency (gPoly/gM) 0.21 0.09 *1.0E6 Catalyst Flow
(lb/hr) 0.73 1.65 Catalyst Conc. (ppm) 500 500 Cocatalyst-1 Flow
(lb/hr) 0.73 1.65 Cocatalyst-1 Conc. (ppm) 4693 4693 Cocatalyst-2
Flow (lb/hr) 0.84 0.63 Cocatatlyst-2 Conc. (ppm) 1995 1995 DEZ Flow
(lb/hr) 2.34 0 DEZ Conc. (ppm) 49989 0
TABLE-US-00002 TABLE 2 CBC Characterization Data Wt. % PP from
Total T.sub.m (.degree. C.) Melt HTLC Mw Mw/ wt % Peak 1 Tc
Enthalpy CBC MFR Separation (Kg/mol) Mn C.sub.2* (Peak 2) (.degree.
C.) (J/g) CBCI CBC 1 9.8 19.9 103.6 2.73 47.6 107.9 (130.0) 87.8 95
0.549 CBC 2 37.6 14.8 73.9 3.74 46.7 130 (103) 92 92 0.697
[0085] Calculation of Composition of Crystalline Block Composite a
summation of the weight % propylene from each component in the
polymer according to equation 1 results in the overall weight %
propylene and/or ethylene (of the whole polymer). This mass balance
equation can be used to quantify the amount of the polypropylene
(PP) and polyethylene (PE) present in the block copolymer. This
mass balance equation can also be used to quantify the amount of PP
and PE in a binary blend or extended to a ternary or n-component
blend. For the crystalline block composite, the overall amount of
PP or PE is contained within the blocks present in the block and
the unbound PP and PE polymers.
Wt%C3.sub.Overall=w.sub.PP(wt%C3.sub.PP)+w.sub.PE(wt%C3.sub.PE) Eq.
1
[0086] where
w.sub.PP=weight fraction of PP in the polymer w.sub.PE=weight
fraction of PE in the polymer wt % C3.sub.PP=weight percent of
propylene in PP component or block wt % C3.sub.PE=weight percent of
propylene in PE component or block.
[0087] Note that the overall weight % of propylene (C.sub.3) is
preferably measured from C.sup.13 NMR or some other composition
measurement that represents the total amount of C.sub.3 present in
the whole polymer. The weight % propylene in the PP block (wt %
C.sub.3PP) is set to 100 or if otherwise known from its DSC melting
point, NMR measurement, or other composition estimate, that value
can be put into its place. Similarly, the weight % propylene in the
PE block (wt % C.sub.3PE) is set to 100 or if otherwise known from
its DSC melting point, NMR measurement, or other composition
estimate, that value can be put into its place.
[0088] Crystalline Block Composite Index (CBCI) is measured based
on the method shown in Table 3, below. In particular, CBCI provides
an estimate of the quantity of block copolymer within the
crystalline block composite under the assumption that the ratio of
CEB to CAOB within a diblock copolymer is the same as the ratio of
crystalline ethylene to crystalline alpha-olefin in the overall
crystalline block composite. This assumption is valid for these
statistical olefin block copolymers based on the understanding of
the individual catalyst kinetics and the polymerization mechanism
for the formation of the diblocks via chain shuttling catalysis as
described in the specification. This CBCI analysis shows that the
amount of isolated PP is less than if the polymer was a simple
blend of a propylene homopolymer (in this example the CAOP) and
polyethylene (in this example the CEP). Consequently, the
polyethylene fraction contains an appreciable amount of propylene
that would not otherwise be present if the polymer was simply a
blend of polypropylene and polyethylene. To account for this "extra
propylene", a mass balance calculation can be performed to estimate
the CBCI from the amount of the polypropylene and polyethylene
fractions and the weight percent propylene present in each of the
fractions that are separated by high temperature liquid
chromatography (HTLC). CBCI is calculated as shown in Table 3 based
on the following:
TABLE-US-00003 TABLE 3 Line # Variable Source CBC1 CBC2 1 Overall
wt % C3 Total Measured 52.400 52.4 2 wt % C3 in PP block/polymer
Measured 99.000 99 3 wt % C3 in PE block/polymer Measured 10.500
8.0 4 wt fraction PP (in block or Eq. 2 below 0.500 0.488 polymer)
5 wt fraction PE (in block or 1-Line 4 0.500 0.512 polymer)
Analysis of HTLC Separation 6 wt fraction isolated PP Measured
0.199 0.148 7 wt fraction PE fraction Measured 0.801 0.852 8 wt %
C3 in PE-fraction Eq. 4 below 40.823 44.3 9 wt fraction PP-diblock
in Eq. 6 below 0.343 0.399 PE fraction 10 wt fraction PE in PE
fraction 1-Line 10 0.657 0.601 11 wt fraction Diblock in 10/Line 4
0.685 0.818 PE fraction 12 Crystalline Block Composite Eq. 7 below
0.549 0.697 Index (CBCI)
[0089] Referring to Table 3, above, crystalline block composite
index (CBCI) is measured by first determining a summation of the
weight percent propylene from each component in the polymer
according to Equation 1, below, which results in the overall weight
percent, as discussed above with respect to the Methods for
Calculation of Composition of Crystalline Block Composite. In
particular, the mass balance equation is as follows:
Wt%C3.sub.Overall=w.sub.PP(wt %C3.sub.PP)+w.sub.PE(wt %C3.sub.PE)
Eq. 1
[0090] where
w.sub.PP=weight fraction of PP in the polymer w.sub.PE=weight
fraction of PE in the polymer wt % C3.sub.PP=weight percent of
propylene in PP component or block wt % C3.sub.PE=weight percent of
propylene in PE component or block For calculating the Ratio of PP
to PE in the crystalline block composite:
[0091] Based on Equation 1, the overall weight fraction of PP
present in the polymer can be calculated using Equation 2 from the
mass balance of the total C3 measured in the polymer.
Alternatively, it could also be estimated from a mass balance of
the monomer and comonomer consumption during the polymerization.
Overall, this represents the amount of PP and PE present in the
polymer regardless of whether it is present in the unbound
components or in the diblock copolymer. For a conventional blend,
the weight fraction of PP and weight fraction of PE corresponds to
the individual amount of PP and PE polymer present. For the
crystalline block composite, it is assumed that the ratio of the
weight fraction of PP to PE also corresponds to the average block
ratio between PP and PE present in this statistical block
copolymer.
w PP = wt % C 3 Overall - wt % C 3 PE wt % C 3 PP - wt % C 3 PE Eq
. 2 ##EQU00001##
[0092] where
w.sub.PP=weight fraction of PP present in the whole polymer wt %
C3.sub.PP=weight percent of propylene in PP component or block wt %
C3.sub.PE=weight percent of propylene in PE component or block
[0093] To estimate the amount of the block in the Crystalline Block
Composite, apply Equations 3 through 5, and the amount of the
isolated PP that is measured by HTLC analysis is used to determine
the amount of polypropylene present in the diblock copolymer. The
amount isolated or separated first in the HTLC analysis represents
the `unbound PP` and its composition is representative of the PP
hard block present in the diblock copolymer. By substituting the
overall weight percent C3 of the whole polymer in the left hand
side of Equation 3, and the weight fraction of PP (isolated from
HTLC) and the weight fraction of PE (separated by HTLC) into the
right hand side of equation 3, the weight percent of C3 in the PE
fraction can be calculated using Equations 4 and 5. The PE fraction
is described as the fraction separated from the unbound PP and
contains the diblock and unbound PE. The composition of the
isolated PP is assumed to be the same as the weight percent
propylene in the iPP block as described previously.
wt % C 3 Overall = w PP isolated ( wt % C 3 PP ) + w PE - fraction
( wt % C 3 PE - fraction ) Eq . 3 wt % C 3 PE - fraction = wt % C 3
Overall - w PPisolated ( wt % C 3 PP ) w PE - fraction Eq . 4 w PE
- fraction = 1 - w PPisolated Eq . 5 ##EQU00002##
[0094] where
w.sub.PPisolated=weight fraction of isolated PP from HTLC
w.sub.PE-fraction=weight fraction of PE separated from HTLC,
containing the diblock and unbound PE wt % C3.sub.PP=weight percent
of propylene in the PP; which is also the same amount of propylene
present in the PP block and in the unbound PP wt %
C3.sub.PE-fraction=weight percent of propylene in the PE-fraction
that was separated by HTLC wt % C3.sub.Overall=overall weight
percent propylene in the whole polymer
[0095] The amount of wt % C3 in the polyethylene fraction from HTLC
represents the amount of propylene present in the block copolymer
fraction that is above the amount present in the `unbound
polyethylene`. To account for the `additional` propylene present in
the polyethylene fraction, the only way to have PP present in this
fraction is for the PP polymer chain to be connected to a PE
polymer chain (or else it would have been isolated with the PP
fraction separated by HTLC). Thus, the PP block remains adsorbed
with the PE block until the PE fraction is separated.
[0096] The amount of PP present in the diblock is calculated using
Equation 6.
w PP - diblock = wt % C 3 PE - fraction - wt % C 3 PE wt % C 3 PP -
wt % C 3 PE Eq . 6 ##EQU00003##
[0097] Where
wt % C3.sub.PE-fraction=weight percent of propylene in the
PE-fraction that was separated by HTLC (Equation 4) wt %
C3.sub.PP=weight percent of propylene in the PP component or block
(defined previously) wt % C3.sub.PE=weight percent of propylene in
the PE component or block (defined previously)
w.sub.PP-diblock=weight fraction of PP in the diblock separated
with PE-fraction by HTLC
[0098] The amount of the diblock present in this PE fraction can be
estimated by assuming that the ratio of the PP block to PE block is
the same as the overall ratio of PP to PE present in the whole
polymer. For example, if the overall ratio of PP to PE is 1:1 in
the whole polymer, then it assumed that the ratio of PP to PE in
the diblock is also 1:1. Thus the weight fraction of diblock
present in the PE fraction would be weight fraction of PP in the
diblock (w.sub.PP-diblock) multiplied by two. Another way to
calculate this is by dividing the weight fraction of PP in the
diblock (w.sub.PP-diblock) by the weight fraction of PP in the
whole polymer (Equation 2).
[0099] To further estimate the amount of diblock present in the
whole polymer, the estimated amount of diblock in the PE fraction
is multiplied by the weight fraction of the PE fraction measured
from HTLC. To estimate the crystalline block composite index, the
amount of diblock copolymer is determined by Equation 7. To
estimate the CBCI, the weight fraction of diblock in the PE
fraction calculated using Equation 6 is divided by the overall
weight fraction of PP (as calculated in equation 2) and then
multiplied by the weight fraction of the PE fraction. The value of
the CBCI can range from 0 to 1, wherein 1 would be equal to 100%
diblock and zero would be for a material such as a traditional
blend or random copolymer.
CBCI = w PP - diblock w PP w PE - fraction Eq . 7 ##EQU00004##
[0100] where
w.sub.PP-diblock=weight fraction of PP in the diblock separated
with the PE-fraction by HTLC (Equation 6) w.sub.PP=weight fraction
of PP in the polymer w.sub.PE-fraction=weight fraction of PE
separated from HTLC, containing the diblock and unbound PE
(Equation 5)
[0101] For example, if an iPP-PE (i.e., isotactic polypropylene
block and propylene-ethylene block) polymer contains a total of
53.3 wt % C3 and is made under the conditions to produce an PE
polymer with 10 wt % C3 and an iPP polymer containing 99 wt % C3,
the weight fractions of PP and PE are 0.487 to 0.514, respectively
(as calculated using Equation 2).
Bicomponent Filaments & Nonwovens
[0102] The remainder of the example is directed to the materials
and methods used in the manufacturing of the bicomponent filaments.
The materials used in the bicomponent filaments are shown in the
Table 4 below.
TABLE-US-00004 TABLE 4 Resin Type MFI/MFR density Comment Lumicene
Metallocene 25 0.905 Available from MR 2001 PP Total Research ASPUN
6000 PE 19 0.935 Available from the Dow Chemical Company ASPUN 6834
PE 17 0.950 Available from the Dow Chemical Company ASPUN 6850 PE
30 0.955 Available from the Dow Chemical Company
[0103] Table 5 shows the various fibers that were manufactured into
a nonwoven for testing. Sample #s 1 and 2 are comparative samples
while Sample #s 3-10 are inventive samples. In Sample #s 3-9, the
compatibilizer is present in the sheath while for Sample #10 it is
present in the core.
TABLE-US-00005 TABLE 5 Type of Sample Fiber GSM Core Sheath Sample
#1* Mono 20 MR 2001 MR 2001 Sample #2* BICO 20 MR 2001 ASPUN 6000
70/30 Sample #3 BICO 20 MR 2001 95% ASPUN 6000 + 70/30 5% CBC1
Sample #4 BICO 20 MR 2001 90% ASPUN 6000 + 70/30 10% CBC1 Sample #5
BICO 20 MR 2001 85% ASPUN 6000 + 70/30 15% CBC1 Sample #6 BICO 20
MR 2001 90% ASPUN 6000 + 50/50 10% CBC1 Sample #7 BICO 20 MR 2001
90% ASPUN 6000 + 70/30 10% CBC2 Sample #8 BICO 20 MR 2001 90% ASPUN
6850 + 70/30 10% CBC1 Sample #9 BICO 20 MR 2001 90% ASPUN 6834 +
70/30 10% CBC1 Sample #10 BICO 20 95% MR ASPUN 6000 70/30 2001 + 5%
CBC1 *comparative samples
[0104] Table 6 shows the processing conditions used to produce a
nonwoven from the bicomponent filament samples shown in the Table
5. The samples were manufactured on Reicofil 4 spunbond system
having 6827 holes/meter with a hole diameter of 0.6 millimeters.
The core component and the sheath component were melted and
extruded separately, and then combined together through a stack of
distribution plates to create core/sheath filament structures. The
filaments were randomly deposited on a moving belt and subsequently
thermally bonded via a calendar (a roll mill) having two rolls, one
of which was an engraved roll and the other a smooth roll.
TABLE-US-00006 TABLE 6 Total Line Nip Bonding tem- Tech- throughput
Speed Pressure perature E/S Sample nology [kg/h] [m/min] [N/mm]
[.degree. C./.degree. C.] Sample #1* RF 4 227 174 70 155/153 Sample
#2* RF 4 227 174 70 150/148 Sample #3 RF 4 227 174 70 150/148
Sample #4 RF 4 227 174 70 150/148 Sample #5 RF 4 227 174 70 150/148
Sample #6 RF 4 227 174 70 150/148 Sample #7 RF 4 227 174 70 150/148
Sample #8 RF 4 227 174 70 150/148 Sample #9 RF 4 227 174 70 150/148
Sample #10 RF 4 227 174 70 150/148 *comparative samples
[0105] Table 7 shows the mechanical properties of the nonwoven
samples of Table 5, 4 weeks and 8 weeks after production.
TABLE-US-00007 TABLE 7 CD Max CD Elon- MD Max MD Elon- tensile
gation at tensile gation at # of Strength break Strength break
Sample weeks [N/50 mm] [%] [N/50 mm] [%] Sample 4 23.6 52 33.7 45
#1* 8 21.6 46 31.7 40 Sample 4 15.6 105 25.9 99 #2* 8 16 111 25.6
94 Sample 4 15.9 107 25.8 98 #3 8 16.4 118 25.5 98 Sample 4 16.7
106 23.9 83 #4 8 16 104 24.9 91 Sample 4 16.8 100 21.1 82 #5 8 15.5
91 22.9 72 Sample 4 13 99 20.2 84 #6 8 12.6 88 19 80 Sample 4 14.5
84 21.4 58 #7 8 16 89 21.8 62 Sample 4 12.8 141 24.1 129 #8 8 13.3
146 23.8 118 Sample 4 13.3 131 23.1 110 #9 8 13.2 126 22.9 107
*comparative samples
[0106] From the Table 7, it may be seen that the nonwoven fabrics
having the bicomponent filaments disclosed herein display an
improvement in abrasion resistance, without any significant adverse
effect on the tensile properties. Also, from Tables 7 & 8, a
significant difference in tensile properties and abrasion
resistance is not observed after 4 and 8 weeks of aging.
[0107] Table 8 shows the fuzz level as a measure of abrasion
resistance of nonwoven fabric. Lower fuzz level indicates better
abrasion resistance
TABLE-US-00008 TABLE 8 1 week after 4 weeks after 8 weeks after
production production production Sample (g/cm.sup.2) (g/cm.sup.2)
(g/cm.sup.2) Sample #1* 0.31 0.23 0.26 Sample #2* 0.35 0.33 0.35
Sample #3 0.33 0.33 0.33 Sample #4 0.29 0.24 0.29 Sample #5 0.25
0.28 0.25 Sample #6 0.24 0.26 0.22 Sample #7 0.24 0.26 0.29 Sample
#8 0.27 0.25 0.24 Sample #9 0.25 0.22 0.21 *comparative samples
[0108] From the data in the Table 8 it may be seen that the
inventive samples (Sample #3-9) show an improvement in abrasion
resistance over time.
[0109] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0110] Every document cited herein, if any, including any
cross-referenced or related patent or application and any patent
application or patent to which this application claims priority or
benefit thereof, is hereby incorporated herein by reference in its
entirety unless expressly excluded or otherwise limited. The
citation of any document is not an admission that it is prior art
with respect to any invention disclosed or claimed herein or that
it alone, or in any combination with any other reference or
references, teaches, suggests or discloses any such invention.
Further, to the extent that any meaning or definition of a term in
this document conflicts with any meaning or definition of the same
term in a document incorporated by reference, the meaning or
definition assigned to that term in this document shall govern.
[0111] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *