U.S. patent application number 13/473925 was filed with the patent office on 2013-04-11 for fibers of polymer-wax compositions.
The applicant listed for this patent is Olaf Erik Alexander Isele, William Maxwell Allen, JR., Eric Bryan Bond, Ronald Thomas Gorley, Isao Noda. Invention is credited to Olaf Erik Alexander Isele, William Maxwell Allen, JR., Eric Bryan Bond, Ronald Thomas Gorley, Isao Noda.
Application Number | 20130089747 13/473925 |
Document ID | / |
Family ID | 46168649 |
Filed Date | 2013-04-11 |
United States Patent
Application |
20130089747 |
Kind Code |
A1 |
Allen, JR.; William Maxwell ;
et al. |
April 11, 2013 |
Fibers of Polymer-Wax Compositions
Abstract
Disposable article that include fibers formed from compositions
comprising thermoplastic polymers and waxes are disclosed, where
the wax is dispersed throughout the thermoplastic polymer.
Inventors: |
Allen, JR.; William Maxwell;
(Liberty Twp., OH) ; Bond; Eric Bryan;
(Maineville, OH) ; Noda; Isao; (Fairfield, OH)
; Gorley; Ronald Thomas; (Cincinnati, OH) ;
Alexander Isele; Olaf Erik; (West Chester, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Allen, JR.; William Maxwell
Bond; Eric Bryan
Noda; Isao
Gorley; Ronald Thomas
Alexander Isele; Olaf Erik |
Liberty Twp.
Maineville
Fairfield
Cincinnati
West Chester |
OH
OH
OH
OH
OH |
US
US
US
US
US |
|
|
Family ID: |
46168649 |
Appl. No.: |
13/473925 |
Filed: |
May 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61488551 |
May 20, 2011 |
|
|
|
Current U.S.
Class: |
428/484.1 ;
524/275 |
Current CPC
Class: |
B01J 20/264 20130101;
C09D 177/04 20130101; D10B 2321/02 20130101; B01J 20/261 20130101;
B01J 20/262 20130101; A61L 15/34 20130101; C08L 77/00 20130101;
C09D 123/10 20130101; C08L 91/06 20130101; D01F 6/46 20130101; B01J
20/28023 20130101; C08K 5/101 20130101; C08K 5/101 20130101; C09D
167/00 20130101; D01F 6/92 20130101; C09D 167/04 20130101; A61L
15/24 20130101; Y10T 428/31801 20150401; C08L 67/02 20130101; D01F
6/90 20130101; B01J 20/265 20130101; C08L 23/06 20130101; A61L
15/24 20130101; C08L 23/16 20130101; D04H 1/4291 20130101; C08L
23/12 20130101; C09D 123/08 20130101; D10B 2201/01 20130101; C08L
67/04 20130101; C08L 23/10 20130101; C08L 23/10 20130101; C08L
23/12 20130101 |
Class at
Publication: |
428/484.1 ;
524/275 |
International
Class: |
C08L 91/06 20060101
C08L091/06; C08L 23/06 20060101 C08L023/06; B01J 20/26 20060101
B01J020/26; C08L 67/04 20060101 C08L067/04; C08L 77/00 20060101
C08L077/00; C08L 67/02 20060101 C08L067/02; C08L 23/12 20060101
C08L023/12; C08L 23/16 20060101 C08L023/16 |
Claims
1. A disposable article comprising: fibers that are produced by
melt spinning a composition comprising an intimate admixture of (a)
a thermoplastic polymer; and (b) a wax having a melting point
greater than 25.degree. C.
2. The disposable article of claim 1, wherein the thermoplastic
polymer comprises a polyolefin, a polyester, a polyamide,
copolymers thereof, or combinations thereof.
3. The disposable article of claim 2, wherein the thermoplastic
polymer is selected from the group consisting of polypropylene,
polyethylene, polypropylene co-polymer, polyethylene co-polymer,
polyethylene terephthalate, polybutylene terephthalate, polylactic
acid, polyhydroxyalkanoates, polyamide-6, polyamide-6,6, and
combinations thereof.
4. The disposable article of claim 1, wherein the thermoplastic
polymer comprises polypropylene.
5. The disposable article of claim 4, wherein the polypropylene has
a weight average molecular weight of about 20 kDa to about 400
kDa.
6. The disposable article of claim 4, wherein the polypropylene has
a melt flow index of greater than 5 g/10 min.
7. The disposable article of claim 6, wherein the polypropylene has
a melt flow index of greater than 10 g/10 min.
8. The disposable article of claim 1, comprising about 5 wt % to
about 40 wt % of the wax, based upon the total weight of the
composition.
9. The disposable article of claim 8, comprising about 10 wt % to
about 20 wt % of the wax, based upon the total weight of the
composition
10. The disposable article of claim 1, wherein the wax comprises a
lipid.
11. The disposable article of claim 10, wherein the lipid comprises
a monoglyceride, diglyceride, triglyceride, fatty acid, fatty
alcohol, esterified fatty acid, epoxidized lipid, maleated lipid,
hydrogenated lipid, alkyd resin derived from a lipid, sucrose
polyester, or combinations thereof.
12. The disposable article of claim 1, wherein the wax comprises a
mineral wax.
13. The disposable article of claim 11, wherein the mineral wax
comprises a linear alkane, a branched alkane, or combinations
thereof.
14. The disposable article of claim 1, wherein the wax is selected
from the group consisting of hydrogenated soy bean oil, partially
hydrogenated soy bean oil, epoxidized soy bean oil, maleated soy
bean oil, tristearin, tripalmitin, 1,2-dipalmitoolein,
1,3-dipalmitoolein, 1-palmito-3-stearo-2-olein,
1-palmito-2-stearo-3-olein, 2-palmito-1-stearo-3-olein,
1,2-dipalmitolinolein, 1,2-distearo-olein, 1,3-distearo-olein,
trimyristin, trilaurin, capric acid, caproic acid, caprylic acid,
lauric acid, myristic acid, palmitic acid, stearic acid, and
combinations thereof.
15. The disposable article of claim 1, wherein the wax is selected
from the group consisting of a hydrogenated plant oil, a partially
hydrogenated plant oil, an epoxidized plant oil, a maleated plant
oil, and combinations thereof.
16. The disposable article of claim 15, wherein the plant oil is
soy bean oil, corn oil, canola oil, palm kernel oil, or a
combination thereof.
17. The disposable article of claim 1, wherein the wax is dispersed
within the thermoplastic polymer such that the wax has a droplet
size of less than 2 .mu.m within the thermoplastic polymer.
18. The disposable article of claim 1, further comprising an
additive.
19. The disposable article of claim 18, wherein the additive is a
perfume, dye, pigment, surfactant, nanoparticle, antistatic agent,
filler, or combination thereof.
20. The disposable article of claim 1, wherein said article is a
disposable absorbent article comprising a liquid pervious layer, a
liquid impervious layer and an absorbent core disposed between said
liquid pervious layer and said liquid impervious layer.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/488,551, filed May 20, 2011, the substance of
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] In one aspect, the invention relates to fibers formed from
compositions comprising intimate admixtures of thermoplastic
polymers and waxes. Another aspect of the invention also relates to
methods of making those compositions.
BACKGROUND OF THE INVENTION
[0003] Thermoplastic polymers are used in a wide variety of
applications. However, thermoplastic polymers, such as
polypropylene and polyethylene pose additional challenges compared
to other polymer species, especially with respect to formation of,
for example, fibers. This is because the material and processing
requirements for production of fibers are much more stringent than
for producing other forms, for example, films. For the production
of fibers, polymer melt flow characteristics are more demanding on
the material's physical and rheological properties vs other polymer
processing methods. Also, the local extensional rate and shear rate
are much greater in fiber production than other processes and, for
spinning very fine fibers, small defects, slight inconsistencies,
or phase incompatibilities in the melt are not acceptable for a
commercially viable process. Moreover, high molecular weight
thermoplastic polymers cannot be easily or effectively spun into
fine fibers. Given their availability and potential strength
improvement, it would be desirable to provide a way to easily and
effectively spin such high molecular weight polymers.
[0004] Most thermoplastic polymers, such as polyethylene,
polypropylene, and polyethylene terephthalate, are derived from
monomers (e.g., ethylene, propylene, and terephthalic acid,
respectively) that are obtained from non-renewable, fossil-based
resources (e.g., petroleum, natural gas, and coal). Thus, the price
and availability of these resources ultimately have a significant
impact on the price of these polymers. As the worldwide price of
these resources escalates, so does the price of materials made from
these polymers. Furthermore, many consumers display an aversion to
purchasing products that are derived solely from petrochemicals,
which are non-renewable fossil based resources. Other consumers may
have adverse perceptions about products derived from petrochemicals
as being "unnatural" or not environmentally friendly.
[0005] Thermoplastic polymers are often incompatible with, or have
poor miscibility with additives (e.g., waxes, pigments, organic
dyes, perfumes, etc.) that might otherwise contribute to a reduced
consumption of these polymers in the manufacture of downstream
articles. Heretofore, the art has not effectively addressed how to
reduce the amount of thermoplastic polymers derived from
non-renewable, fossil-based resources in the manufacture of common
articles employing these polymers. Accordingly, it would be
desirable to address this deficiency. Existing art has combined
polypropylene with additives, with polypropylene as the minor
component to form cellular structures. These cellular structures
are the purpose behind including renewable materials that are later
removed or extracted after the structure is formed. U.S. Pat. No.
3,093,612 describes the combination of polypropylene with various
fatty acids where the fatty acid is removed. The scientific paper
J. Apply. Polym. Sci 82 (1) pp. 169-177 (2001) discloses use of
diluents on polypropylene for thermally induced phase separation to
produce an open and large cellular structure but at low polymer
ratio, where the diluent is subsequently removed from the final
structure. The scientific paper J. Apply. Polym. Sci 105 (4) pp.
2000-2007 (2007) produces microporous membranes via thermally
induced phase separation with dibutyl phthalate and soy bean oil
mixtures, with a minor component of polypropylene. The diluent is
removed in the final structure. The scientific paper Journal of
Membrane Science 108 (1-2) pp. 25-36 (1995) produces hollow fiber
microporous membranes using soy bean oil and polypropylene
mixtures, with a minor component of polypropylene and using
thermally induced phase separation to produce the desired membrane
structure. The diluent is removed in the final structure. In all of
these cases, the diluent as described is removed to produce the
final structure. These structures before the diluent is removed are
oily with excessive amounts of diluent to produce very open
microporous structures with pore sizes >10 .mu.m.
[0006] There have been many attempts to make nonwoven articles.
However, because of costs, the difficultly in processing, and
end-use properties, there are only a limited number of options.
Useful fibers for nonwoven articles are difficult to produce and
pose additional challenges compared to films and laminates. This is
because the material and processing characteristics for fibers is
much more stringent than for producing films, blow-molding
articles, and injection-molding articles. For the production of
fibers, the processing time during structure formation is typically
much shorter and flow characteristics are more demanding on the
material's physical and rheological characteristics. The local
strain rate and shear rate are much greater in fiber production
than other processes. Additionally, a homogeneous composition is
required for fiber spinning. For spinning very fine fibers, small
defects, slight inconsistencies, or non-homogeneity in the melt are
not acceptable for a commercially viable process. The more
attenuated the fibers, the more critical the processing conditions
and selection of materials.
[0007] Thus, a need exists for fibers from compositions of
thermoplastic polymers that allow for use of higher molecular
weight and/or decreased non-renewable resource based materials,
and/or incorporation of further additives, such as perfumes and
dyes. A still further need is for fibers from compositions that
leave the additive present to deliver renewable materials in the
final product and that can also enable the addition of further
additives into the final structure, such as dyes and perfumes, for
example.
SUMMARY OF THE INVENTION
[0008] In one aspect, the invention is directed to fibers produced
by melt spinning compositions comprising an intimate admixture of a
thermoplastic polymer and a wax having a melting point greater than
25.degree. C. The wax can have a melting point that is lower than
the melting temperature of the thermoplastic polymer. The
composition can be in the form of pellets produced to be used as-is
or for storage for future use, for example to make fibers.
Optionally, the composition can be further processed into the final
usable form, such as fibers, films and molded articles. The fibers
can have a diameter of less than 200 .mu.m. The fibers can be
monocomponent or bicomponent, discrete and/or continuous, in
addition to being hollow, round, and/or shaped. The fiber can be
thermally bondable.
[0009] The thermoplastic polymer can comprise a polyolefin, a
polyester, a polyamide, copolymers thereof, or combinations
thereof. The thermoplastic polymer can be selected from the group
consisting of polypropylene, polyethylene, polypropylene
co-polymer, polyethylene co-polymer, polyethylene terephthalate,
polybutylene terephthalate, polylactic acid, polyhydroxyalkanoates,
polyamide-6, polyamide-6,6, and combinations thereof. Polypropylene
having a melt flow index of greater than 0.5 g/10 min or of greater
than 10 g/10 min can be used. The polypropylene can have a weight
average molecular weight of about 20 kDa to about 700 kDa. The
thermoplastic polymer can be derived from a renewable bio-based
feed stock origin, such as bio polyethylene or bio polypropylene,
and/or can be recycled source, such as post consumer use.
[0010] The wax can be present in the composition in an amount of
amount 1 wt % to about 20 wt %, about 2 wt % to about 15 wt %, or
about 3 wt % to about 10 wt % based upon the total weight of the
composition. The wax can comprise a lipid, which can be selected
from the group consisting of a monoglyceride, diglyceride,
triglyceride, fatty acid, fatty alcohol, esterified fatty acid,
epoxidized lipid, maleated lipid, hydrogenated lipid, alkyd resin
derived from a lipid, sucrose polyester, or combinations thereof.
The wax can comprise a mineral wax, such as a linear alkane, a
branched alkane, or combinations thereof. Specific examples of
mineral wax are paraffin and petrolatum. The wax can be selected
from the group consisting of hydrogenated soy bean oil, partially
hydrogenated soy bean oil, epoxidized soy bean oil, maleated soy
bean oil, tristearin, tripalmitin, 1,2-dipalmitoolein,
1,3-dipalmitoolein, 1-palmito-3-stearo-2-olein,
1-palmito-2-stearo-3-olein, 2-palmito-1-stearo-3-olein,
1,2-dipalmitolinolein, 1,2-distearo-olein, 1,3-distearo-olein,
trimyristin, trilaurin, capric acid, caproic acid, caprylic acid,
lauric acid, myristic acid, palmitic acid, stearic acid, and
combinations thereof. The wax can be selected from the group
consisting of a hydrogenated plant oil, a partially hydrogenated
plant oil, an epoxidized plant oil, a maleated plant oil. Specific
examples of such plant oils include soy bean oil, corn oil, canola
oil, and palm kernel oil.
[0011] The wax can be dispersed within the thermoplastic polymer
such that the wax has a droplet size of less than 2 .mu.m, less
than 1 .mu.m, or less than 500 nm within the thermoplastic polymer.
The wax can be a renewable material.
[0012] The compositions disclosed herein can further comprise an
additive. The additive can be oil soluble or oil dispersible.
Examples of additives include perfume, dye, pigment, nucleating
agent, clarifying agent, anti-microbial agent, surfactant,
nonoparticle, antistatic agent, filler, or combination thereof.
[0013] In another aspect, provided is a method of making a
composition as disclosed herein, the method comprising a) mixing
the thermoplastic polymer, in a molten state, with the wax, also in
the molten state, to form the admixture; and b) cooling the
admixture to a temperature at or less than the solidification
temperature of the thermoplastic polymer in 10 seconds or less to
form the composition. The method of making a composition can
comprise a) melting a thermoplastic polymer to form a molten
thermoplastic polymer; b) mixing the molten thermoplastic polymer
and a wax to form an admixture; and c) cooling the admixture to a
temperature at or less than the solidification temperature of the
thermoplastic polymer in 10 seconds or less. The mixing can be at a
shear rate of greater than 10 s.sup.-1, or about 30 to about 100
s.sup.-1. The admixture can be cooled in 10seconds or less to a
temperature of 50.degree. C. or less. The composition can be
palletized. The pelletizing can occur after cooling the admixture
or before or simultaneous to cooling the admixture. The composition
can be made using an extruder, such as a single- or twin-screw
extruder. Alternatively, the method of making a composition can
comprise a) melting a thermoplastic polymer to form a molten
thermoplastic polymer; b) mixing the molten thermoplastic polymer
and a wax to form an admixture; and c) spinning the molten mixture
to form filaments or fibers which solidify upon cooling.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] For a more complete understanding of the disclosure,
reference should be made to the following detailed description and
accompanying drawing wherein:
[0015] FIG. 1 shows the viscosity of unmodified polypropylene and
Examples 1-3, compositions as disclosed herein;
[0016] FIG. 2 shows scanning electron microscopy (SEM) images of
unmodified polypropylene (A) and Examples 1-3 (B-D), compositions
as disclosed herein; and
[0017] FIG. 3 is a schematic representation of a disposable
absorbent article.
[0018] While the disclosed invention is susceptible of embodiments
in various forms, there are illustrated in the drawings (and will
hereafter be described) specific embodiments of the invention, with
the understanding that the disclosure is intended to be
illustrative, and is not intended to limit the invention to the
specific embodiments described and illustrated herein.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Fibers disclosed herein are made by melt spinning
compositions of an intimate admixture of a thermoplastic polymer
and a wax. The term "intimate admixture" refers to the physical
relationship of the wax and thermoplastic polymer, wherein the wax
is dispersed within the thermoplastic polymer. The droplet size of
the wax within the thermoplastic polymer is a parameter that
indicates the level of dispersion of the wax within the
thermoplastic polymer. The smaller the droplet size, the higher the
dispersion of the wax within the thermoplastic polymer, the larger
the droplet size the lower the dispersion of the wax within the
thermoplastic polymer. As used herein, the term "admixture" refers
to the intimate admixture of the one of the inventions disclosed
herein, and not an "admixture" in the more general sense of a
standard mixture of materials.
[0020] The droplet size of the wax within the thermoplastic polymer
is less than 2 .mu.m and can be less than 1 .mu.m, or less than 500
nm. Other contemplated droplet sizes of the wax dispersed within
the thermoplastic polymer include less than 1.5 .mu.m, less than
900 nm, less than 800 nm, less than 700 nm, less than 600 nm, less
than 400 nm, less than 300 nm, and less than 200 nm.
[0021] The droplet size of the wax can be measured by scanning
electron microscopy (SEM) indirectly by measuring a void size in
the thermoplastic polymer, after removal of the wax from the
composition. Removal of the wax is typically performed prior to SEM
imaging due to incompatibility of the wax and the SEM imaging
technique. Thus, the void measured by SEM imaging is correlated to
the droplet size of the wax in the composition, as exemplified in
FIG. 2.
[0022] One exemplary way to achieve a suitable dispersion of the
wax within the thermoplastic polymer is by admixing the
thermoplastic polymer, in a molten state, and the wax. The
thermoplastic polymer is melted (e.g., exposed to temperatures
greater than the thermoplastic polymer's solidification
temperature) to provide the molten thermoplastic polymer and mixed
with the wax. The thermoplastic polymer can be melted prior to
addition of the wax or can be melted in the presence of the wax. It
should be understood that when the polymer is melted, the wax is
also in the molten state. The term wax hereafter can refer to the
component either in the solid (optionally crystalline) state or in
the molten state, depending on the temperature. It is not required
that the wax be solidified at a temperature at which the polymer is
solidified. For example, polypropylene is a semi-crystalline solid
at 90.degree. C., which is above the melting point of many
waxes.
[0023] The thermoplastic polymer and wax can be mixed, for example,
at a shear rate of greater than 10 s.sup.-1. Other contemplated
shear rates include greater than 10, about 15 to about 1000, about
20 to about 200 or up to 500 s.sup.-1. The higher the shear rate of
the mixing, the greater the dispersion of the wax in the
composition as disclosed herein. Thus, the dispersion can be
controlled by selecting a particular shear rate during formation of
the composition.
[0024] The wax and molten thermoplastic polymer can be mixed using
any mechanical means capable of providing the necessary shear rate
to result in a composition as disclosed herein. Non-limiting
examples of mechanical means include a mixer, such as a Haake batch
mixer, and an extruder (e.g., a single- or twin-screw
extruder).
[0025] The mixture of molten thermoplastic polymer and wax is then
rapidly (e.g., in less than 10 seconds) cooled to a temperature
lower than the solidification temperature (either via traditional
thermoplastic polymer crystallization or passing below the polymer
glass transition temperature) of the thermoplastic polymer. The
admixture can be cooled to less than 200.degree. C., less than
150.degree. C., less than 100.degree. C. less than 75.degree. C.,
less than 50.degree. C., less than 40.degree. C., less than
30.degree. C., less than 20.degree. C., less than 15.degree. C.,
less than 10.degree. C., or to a temperature of about 0.degree. C.
to about 30.degree. C., about 0.degree. C. to about 20.degree. C,
or about 0.degree. C. to about 10.degree. C. For example, the
mixture can be placed in a low temperature liquid (e.g., the liquid
is at or below the temperature to which the mixture is cooled) or
gas. The liquid can be ambient or controlled temperature water. The
gas can be ambient air or controlled temperature and humidity air.
Any quenching media can be used so long as it cools the admixture
rapidly. Additional liquids such as oils, alcohols and ketones can
be used for quenching, along with mixtures comprising water (sodium
chloride for example) depending on the admixture composition.
Additional gases can be used, such as carbon dioxide and nitrogen,
or any other component naturally occurring in atmospheric
temperature and pressure air.
[0026] Optionally, the composition is in the form of pellets.
Pellets of the composition can be formed prior to, simultaneous to,
or after cooling of the mixture. The pellets can be formed by
strand cutting or underwater pelletizing. In strand cutting, the
composition is rapidly quenched (generally in a time period much
less than 10 seconds) then cut into small pieces. In underwater
pelletizing, the mixture is cut into small pieces and
simultaneously or immediately thereafter placed in the presence of
a low temperature liquid that rapidly cools and solidifies the
mixture to form the pelletized composition. Such pelletizing
methods are well understood by the ordinarily skilled artisan.
Pellet morphologies can be round or cylindrical, and can have no
dimension larger than 15 mm, more preferably less than 10 mm, or no
dimension larger than 5 mm.
[0027] Alternatively, the admixture (admixture and mixture or used
interchangeably here within this document) can be used whilst mixed
in the molten state and formed directly into fibers.
Thermoplastic Polymers
[0028] Thermoplastic polymers, as used in the disclosed
compositions, are polymers that melt and then, upon cooling,
crystallize or harden, but can be re-melted upon further heating.
Suitable thermoplastic polymers used herein have a melting
temperature from about 60.degree. C. to about 300.degree. C., from
about 80.degree. C. to about 250.degree. C., or from 100.degree. C.
to 215.degree. C.
[0029] The thermoplastic polymers can be derived from renewable
resources or from fossil minerals and oils. The thermoplastic
polymers derived from renewable resources are bio-based, for
example such as bio produced ethylene and propylene monomers used
in the production polypropylene and polyethylene. These material
properties are essentially identical to fossil based product
equivalents, except for the presence of carbon-14 in the
thermoplastic polymer. Renewable and fossil based thermoplastic
polymers can be combined together in any of the embodiments of the
invention disclosed herein in any ratio, depending on cost and
availability. Recycled thermoplastic polymers can also be used,
alone or in combination with renewable and/or fossil derived
thermoplastic polymers. The recycled thermoplastic polymers can be
pre-conditioned to remove any unwanted contaminants prior to
compounding or they can be used during the compounding and
extrusion process, as well as simply left in the admixture. These
contaminants can include trace amounts of other polymers, pulp,
pigments, inorganic compounds, organic compounds and other
additives typically found in processed polymeric compositions. The
contaminants should not negatively impact the final performance
properties of the admixture, for example, causing spinning breaks
during a fiber spinning process.
[0030] The molecular weight of the thermoplastic polymer is
sufficiently high to enable entanglement between polymer molecules
and yet low enough to be melt spinnable. Addition of the wax into
the composition allows for compositions containing higher molecular
weight thermoplastic polymers to be spun, compared to compositions
without a wax. Thus, suitable thermoplastic polymers can have
weight average molecular weights of about 1000 kDa or less, about 5
kDa to about 800 kDa, about 10 kDa to about 700 kDa, or about 20
kDa to about 400 kDa. The weight average molecular weight is
determined by the specific method for each polymer, but is
generally measured using either gel permeation chromatography (GPC)
or from solution viscosity measurements. The thermoplastic polymer
weight average molecular weight should be determined before
addition into the admixture.
[0031] Suitable thermoplastic polymers generally include
polyolefins, polyesters, polyamides, copolymers thereof, and
combinations thereof. The thermoplastic polymer can be selected
from the group consisting of polypropylene, polyethylene,
polypropylene co-polymer, polyethylene co-polymer, polyethylene
terephthalate, polybutylene terephthalate, polylactic acid,
polyhydroxyalkanoates, polyamide-6, polyamide-6,6, and combinations
thereof.
[0032] More specifically, however, the thermoplastic polymers
preferably include polyolefins such as polyethylene or copolymers
thereof, including low density, high density, linear low density,
or ultra low density polyethylenes such that the polyethylene
density ranges between 0.90 grams per cubic centimeter to 0.97
grams per cubic centimeter, most preferred between 0.92 and 0.95
grams per cubic centimeter. The density of the polyethylene will is
determined by the amount and type of branching and depends on the
polymerization technology and comonomer type. Polypropylene and/or
polypropylene copolymers, including atactic polypropylene;
isofactic polypropylene, syndiotactic polypropylene, and
combination thereof can also be used. Polypropylene copolymers,
especially ethylene can be used to lower the melting temperature
and improve properties. These polypropylene polymers can be
produced using metallocene and Ziegler-Natta catalyst systems.
These polypropylene and polyethylene compositions can be combined
together to optimize end-use properties. Polybutylene is also a
useful polyolefin.
[0033] Other suitable polymers include polyamides or copolymers
thereof, such as Nylon 6, Nylon 11, Nylon 12, Nylon 46, Nylon 66;
polyesters or copolymers thereof, such as maleic anhydride
polypropylene copolymer, polyethylene terephthalate; olefin
carboxylic acid copolymers such as ethylene/acrylic acid copolymer,
ethylene/maleic acid copolymer, ethylene/methacrylic acid
copolymer, ethylene/vinyl acetate copolymers or combinations
thereof; polyacrylates, polymethacrylates, and their copolymers
such as poly(methyl methacrylates). Other nonlimiting examples of
polymers include polycarbonates, polyvinyl acetates,
poly(oxymethylene), styrene copolymers, polyacrylates,
polymethacrylates, poly(methyl methacrylates), polystyrene/methyl
methacrylate copolymers, polyetherimides, polysulfones, or
combinations thereof. In some embodiments, thermoplastic polymers
include polypropylene, polyethylene, polyamides, polyvinyl alcohol,
ethylene acrylic acid, polyolefin carboxylic acid copolymers,
polyesters, and combinations thereof.
[0034] Biodegradable thermoplastic polymers also are contemplated
for use herein. Biodegradable materials are susceptible to being
assimilated by microorganisms, such as molds, fungi, and bacteria
when the biodegradable material is buried in the ground or
otherwise contacts the microorganisms (including contact under
environmental conditions conducive to the growth of the
microorganisms). Suitable biodegradable polymers also include those
biodegradable materials which are environmentally-degradable using
aerobic or anaerobic digestion procedures, or by virtue of being
exposed to environmental elements such as sunlight, rain, moisture,
wind, temperature, and the like. The biodegradable thermoplastic
polymers can be used individually or as a combination of
biodegradable or non-biodegradable polymers. Biodegradable polymers
include polyesters containing aliphatic components. Among the
polyesters are ester polycondensates containing aliphatic
constituents and poly(hydrosycarboxylic) acid. The ester
polycondensates include diacids/diol aliphatic polyesters such as
polybutylene succinate, polybutylene succinate co-adipate,
aliphatic/aromatic polyesters such as terpolymers made of butylene
diol, adipic acid and terephthalic acid. The
poly(hydroxycarboxylic) acids include lactic acid based
homopolymers and copolymers, polyhydroxybutyrate (PHB), or other
polyhydroxyalkanoate homopolymers and copolymers. Such
polyhydroxyalkanoates include copolymers of PHB with higher chain
length monomers, such as C.sub.6-C12, and higher,
polyhydroxyalkanaotes, such as those disclosed in U.S. Pat. Nos. RE
36,548 and 5,990,271.
[0035] An example of a suitable commercially available polylactic
acid is NATUREWORKS from Cargill Dow and LACEA from Mitsui
Chemical. An example of a suitable commercially available
diacid/diol aliphatic polyester is the polybutylene
succinate/adipate copolymers sold as BIONOLLE 1000 and BIONOLLE
3000 from the Showa High Polymer Company, Ltd. (Tokyo, Japan). An
example of a suitable commercially available aliphatic/aromatic
copolyester is the poly(tetramethylene adipate-co-terephthalate)
sold as EASTAR BIO Copolyester from Eastman Chemical or ECOFLEX
from BASF.
[0036] Non-limiting examples of suitable commercially available
polypropylene or polypropylene copolymers include Basell Profax
PH-835 (a 35 melt flow rate Ziegler-Natta isotactic polypropylene
from Lyondell-Basell), Basell Metocene MF-650W (a 500 melt flow
rate metallocene isotactic polypropylene from Lyondell-Basell),
Polybond 3200 (a 250 melt flow rate maleic anhydride polypropylene
copolymer from Crompton), Exxon Achieve 3854 (a 25 melt flow rate
metallocene isotactic polypropylene from Exxon-Mobil Chemical), and
Mosten NB425 (a 25 melt flow rate Ziegler-Matta isotactic
polypropylene from Unipetrol). Other suitable polymer may include
Danimer 27510 (a polyhydroxyalkanoate polypropylene from Danimer
Scientific LLC), Dow Aspun 6811A (a 27 melt index polyethylene
octene copolymer from Dow Chemical), and Eastman 9921 (a polyester
terephthalic homopolymer with a nominally 0.81 intrinsic viscosity
from Eastman Chemical).
[0037] The thermoplastic polymer component can be a single polymer
species as described above or a blend of two or more thermoplastic
polymers as described above.
[0038] If the polymer is polypropylene, the thermoplastic polymer
can have a melt flow index of greater than 0.5 g/10 min, as
measured by ASTM D-1238, used for measuring polypropylene. Other
contemplated melt flow indices include greater than 5 g/10 min,
greater than 10 g/10 min, or about 5 g/10 min to about 50 g/10
min.
Waxes
[0039] A wax, as used in the disclosed composition, is a lipid,
mineral wax, or combination thereof, wherein the lipid, mineral
wax, or combination thereof has a melting point of greater than
25.degree. C. More preferred is a melting point above 35.degree.
C., still more preferred above 45.degree. C. and most preferred
above 50.degree. C. The wax can have a melting point that is lower
than the melting temperature of the thermoplastic polymer in the
composition. The terms "wax" and "oil" are differentiated by
crystallinity of the component at or near 25.degree. C. In all
cases, the "wax" will have a maximum melting temperature less than
the thermoplastic polymer, preferably less than 100.degree. C. and
most preferably less than 80.degree. C. The wax can be a lipid. The
lipid can be a monoglyceride, diglyceride, triglyceride, fatty
acid, fatty alcohol, esterified fatty acid, epoxidized lipid,
maleated lipid, hydrogenated lipid, alkyd resin derived from a
lipid, sucrose polyester, or combinations thereof. The mineral wax
can be a linear alkane, a branched alkane, or combinations thereof.
The waxes can be partially or fully hydrogenated materials, or
combinations and mixtures thereof, that were formally liquids at
room temperature in their unmodified forms. When the temperature is
above the melting temperature of the wax, it is a liquid oil. When
in the molten state, the wax can be referred to as an "oil". The
terms "wax" and "oil" only have-meaning when measured at 25.degree.
C. The wax will be a solid at 25.degree. C., while an oil is not a
solid at 25.degree. C. Otherwise they are used interchangeably
above 25.degree. C.
[0040] Because the wax may contain a distribution of melting
temperatures to generate a peak melting temperature, the wax
melting temperature is defined as having a peak melting temperature
25.degree. C. or above as defined as when >50 weight percent of
the wax component melts at or above 25.degree. C. This measurement
can be made using a differential scanning calorimeter (DSC), where
the heat of fusion is equated to the weight percent fraction of the
wax.
[0041] The wax number average molecular weight, as determined by
gel permeation chromatography (GPC), should be less than 2 kDa,
preferably less than 1.5 kDa, still more preferred less than 1.2
kDa.
[0042] The amount of wax is determined via gravimetric weight loss
method. The solidified mixture is placed, with the narrowest
specimen dimension no greater than 1 mm, into acetone at a ratio of
1 g or mixture per 100 g of acetone using a refluxing flask system.
First the mixture is weighed before being placed into the reflux
flask, and then the acetone and mixtures are heated to 60.degree.
C. for 20 hours. The sample is removed and air dried for 60 minutes
and a final weight determined. The equation for calculating the
weight percent wax is
weight % wax=([initial mass-final mass]/[initial
mass]).times.100%
[0043] Non-limiting examples of waxes contemplated in the
compositions disclosed herein include beef tallow, castor wax,
coconut wax, coconut seed wax, corn germ wax, cottonseed wax, fish
wax, linseed wax, olive wax, oiticica wax, palm kernel wax, palm
wax, palm seed wax, peanut wax, rapeseed wax, safflower wax,
soybean wax, sperm wax, sunflower seed wax, tall wax, tung wax,
whale wax, and combinations thereof. Non-limiting examples of
specific triglycerides include triglycerides such as, for example,
tristearin, tripalmitin, 1,2-dipalmitoolein, 1,3-dipalmitoolein,
1-palmito-3-stearo-2-olein, 1-palmito-2-stearo-3-olein,
2-palmito-1-stearo-3-olein, 1,2-dipalmitolinolein,
1,2-distearo-olein, 1,3-distearo-olein, trimyristin, trilaurin and
combinations thereof. Non-limiting examples of specific fatty acids
contemplated include capric acid, caproic acid, caprylic acid,
lauric acid, myristic acid, palmitic acid, stearic acid, and
mixtures thereof. Other specific waxes contemplated include
hydrogenated soy bean oil, partially hydrogenated soybean oil,
partially hydrogenated palm kernel oil, and combinations thereof.
Inedible waxes from Jatropha and rapeseed oil can also be used. The
wax can be selected from the group consisting of a hydrogenated
plant oil, a partially hydrogenated plant oil, an epoxidized plant
oil, a maleated plant oil. Specific examples of such plant oils
include soy bean oil, corn oil, canola oil, and palm kernel oil.
Specific examples of mineral wax include paraffin (including
petrolatum), Montan wax, as well as polyolefin waxes produced from
cracking processes, preferentially polyethylene derived waxes.
Mineral waxes and plant derived waxes can be combined together.
Plant based waxes can be differentiated by their carbon-14
content.
[0044] The wax can be from a renewable material (e.g., derived from
a renewable resource). As used herein, a "renewable resource" is
one that is produced by a natural process at a rate comparable to
its rate of consumption (e.g., within a 100 year time frame). The
resource can be replenished naturally, or via agricultural
techniques. Non-limiting examples of renewable resources include
plants (e.g., sugar cane, beets, corn, potatoes, citrus fruit,
woody plants, lignocellulosics, hemicellulosics, cellulosic waste),
animals, fish, bacteria, fungi, and forestry products. These
resources can be naturally occurring, hybrids, or genetically
engineered organisms. Natural resources such as crude oil, coal,
natural gas, and peat, which take longer than 100 years to form,
are not considered renewable resources.
[0045] The wax, as disclosed herein, can be present in the
composition at a weight percent of 1 wt % to 20 wt %, based upon
the total weight of the composition. Other contemplated wt % ranges
of the wax include 2 wt % to 15 wt %, with a preferred range from
about 3 wt % to about 10 wt %. Specific wax wt % contemplated
include about 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, about 6 wt %,
about 7 wt %, about 8 wt %, about 9 wt %, about 10 wt %, about 11
wt %, about 12 wt %, about 13 wt %, about 14 wt %, about 15 wt %,
about 16 wt %, about 17 wt %, about 18 wt %, about 19 wt %, and
about 20 wt, based upon the total weight of the composition.
Additives
[0046] The compositions disclosed herein can further include an
additive. The additive can be dispersed throughout the composition,
or can be substantially in the thermoplastic polymer portion of the
thermoplastic layer or substantially in the wax portion of the
composition. In cases where the additive is in the wax portion of
the composition, the additive can be wax soluble or wax
dispersible.
[0047] Non-limiting examples of classes of additives contemplated
in the compositions disclosed herein include perfumes, dyes,
pigments, nanoparticles, antistatic agents, fillers, and
combinations thereof. The compositions disclosed herein can contain
a single additive or a mixture of additives. For example, both a
perfume and a colorant (e.g., pigment and/or dye) can be present in
the composition. The additive(s), when present, is/are present in a
weight percent of 0.05 wt % to 20 wt %, or 0.1 wt % to 10 wt %.
Specifically contemplated weight percentages include 0.5 wt %, 0.6
wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 1.1 wt %, 1.2 wt %, 1.3
wt %, 1.4 wt %, 1.5 wt %, 1.6 wt %, 1.7 wt %, 1.8 wt %, 1.9 wt %, 2
wt %, 2.1 wt %, 2.2 wt %, 2.3 wt %, 2.4 wt %, 2.5 wt %, 2.6 wt %,
2.7 wt %, 2.8 wt %, 2.9 wt %, 3 wt %, 3.1 wt %, 3.2 wt %, 3.3 wt %,
3.4 wt %, 3.5 wt %, 3.6 wt %, 3.7 wt %, 3.8 wt %, 3.9 wt %, 4 wt %,
4.1 wt %, 4.2 wt %, 4.3 wt %, 4.4 wt %, 4.5 wt %, 4.6 wt %, 4.7 wt
%, 4.8 wt %, 4.9 wt %, 5 wt %, 5.1 wt %, 5.2 wt %, 5.3 wt %, 5.4 wt
%, 5.5 wt %, 5.6 wt %, 5.7 wt %, 5.8 wt %, 5.9 wt %, 6 wt %, 6.1 wt
%, 6.2 wt %, 6.3 wt %, 6.4 wt %, 6.5 wt %, 6.6 wt %. 6.7 wt %, 6.8
wt %, 6.9 wt %, 7 wt %, 7.1 wt. %, 7.2 wt %, 7.3 wt %, 7.4 wt %,
7.5 wt %, 7.6 wt %, 7.7 wt %, 7.8 wt %, 7.9 wt %, 8 wt %, 8.1 wt %,
8.2 wt %, 8.3 wt %, 8.4 wt %, 8.5 wt %, 8.6 wt %, 8.7 wt %, 8.8 wt
%, 8.9 wt %, 9 wt %, 9.1 wt %, 9.2 wt %, 9.3 wt %, 9.4 wt %, 9.5 wt
%, 9.6 wt %, 9.7 wt %, 9.8 wt %, 9.9 wt %, and 10 wt %.
[0048] As used herein the term "perfume" is used to indicate any
odoriferous material that is subsequently released from the
composition as disclosed herein. A wide variety of chemicals are
known for perfume uses, including materials such as aldehydes,
ketones, alcohols, and esters. More commonly, naturally occurring
plant and animal oils and exudates including complex mixtures of
various chemical components are known for use as perfumes. The
perfumes herein can be relatively simple in their compositions or
can include highly sophisticated complex mixtures of natural and
synthetic chemical components, all chosen to provide any desired
odor. Typical perfumes can include, for example, woody/earthy bases
containing exotic materials, such as sandalwood, civet and
patchouli oil. The perfumes can be of a light floral fragrance
(e.g. rose extract, violet extract, and lilac). The perfumes can
also be formulated to provide desirable fruity odors, e.g. lime,
lemon, and orange. The perfumes delivered in the compositions and
articles disclosed herein can be selected for an aromatherapy
effect, such as providing a relaxing or invigorating mood. As such,
any material that exudes a pleasant or otherwise desirable odor can
be used as a perfume active in the compositions and articles
disclosed herein.
[0049] A pigment or dye can be inorganic, organic, or a combination
thereof. Specific examples of pigments and dyes contemplated
include pigment Yellow (C.I. 14), pigment Red (C.I. 48:3), pigment
Blue (C.I. 15:4), pigment Black (C.I. 7), and combinations thereof.
Specific contemplated dyes include water soluble ink colorants like
direct dyes, acid dyes, base dyes, and various solvent soluble
dyes. Examples include, but are not limited to, FD & C Blue 1
(C.I. 42090:2), D & C Red 6 (C.I. 15850), D & C Red 7 (C.I.
15850:1), D & C Red 9 (C.I. 15585:1), D & C Red 21 (C.I.
45380:2), D & C Red 22 (C.I. 45380:3), D & C Red 27 (C.I.
45410:1), D & C Red 28 (C.I. 45410:2), D & C Red 30 (C.I.
73360), D & C Red 33 (C.I. 17200), D & C Red 34 (C.I.
15880:1), and FD & C Yellow 5 (C.I. 19140:1), FD & C Yellow
6 (C.I. 15985:1), FD & C Yellow 10 (C.I. 47005:1), D & C
Orange 5 (C.I. 45370:2), and combinations thereof.
[0050] Contemplated fillers include, but are not limited to
inorganic fillers such as, for example, the oxides of magnesium,
aluminum, silicon, and titanium. These materials can be added as
inexpensive fillers or processing aides. Other inorganic materials
that can function as fillers include hydrous magnesium silicate,
titanium dioxide, calcium carbonate, clay, chalk, boron nitride,
limestone, diatomaceous earth, mica glass quartz, and ceramics.
Additionally, inorganic salts, including alkali metal salts,
alkaline earth metal salts, phosphate salts, can be used.
Additionally, alkyd resins can also be added to the composition.
Alkyd resins comprise a polyol, a polyacid or anhydride, and/or a
fatty acid.
[0051] Additional contemplated additives include nucleating and
clarifying agents for the thermoplastic polymer. Specific examples,
suitable for polypropylene, for example, are benzoic acid and
derivatives (e.g. sodium benzoate and lithium benzoate), as well as
kaolin, talc and zinc glycerolate. Dibenzlidene sorbitol (DBS) is
an example of a clarifying agent that can be used. Other nucleating
agents that can be used are organocarboxylic acid salts, sodium
phosphate and metal salts (for example aluminum dibenzoate) The
nucleating or clarifying agents can be added in ranges from 20
parts per million (20 ppm) to 20,000 ppm, more preferred range of
200 ppm to 2000 ppm and the most preferred range from 1000 ppm to
1500 ppm. The addition of the nucleating agent can be used to
improve the tensile and impact properties of the finished admixture
composition.
[0052] Contemplated surfactants include anionic surfactants,
amphoteric surfactants, or a combination of anionic and amphoteric
surfactants, and combinations thereof, such as surfactants
disclosed, for example, in U.S. Pat. Nos. 3,929,678 and 4,259,217
and in BP414 549, WO93/08876 and WO93/08874.
[0053] Contemplated nanoparticles include metals, metal oxides,
allotropes of carbon, clays, organically modified clays, sulfates,
nitrides, hydroxides, oxy/hydroxides, particulate water-insoluble
polymers, silicates, phosphates and carbonates. Examples include
silicon dioxide, carbon black, graphite, grapheme, fullerenes,
expanded graphite, carbon, nanotubes, talc, calcium carbonate,
betonite, montmorillonite, kaolin, zinc glycerolate, silica,
aluminosilicates, boron nitride, aluminum nitride, barium sulfate,
calcium sulfate, antimony oxide, feldspar, mica, nickel, copper,
iron, cobalt, steel, gold, silver, platinum, aluminum,
wollastonite, aluminum oxide, zirconium oxide, titanium dioxide,
cerium oxide, zinc oxide, magnesium oxide, tin oxide, iron oxides
(Fe.sub.2O.sub.3, Fe.sub.3O.sub.4) and mixtures thereof.
Nanoparticles can increase strength, thermal stability, and/or
abrasion resistance of the compositions disclosed herein, and can
give the compositions electric properties.
[0054] It is contemplated to add oils or that some amount of oil is
present in the composition. The oil may be unrelated to the lipid
present or can be an unsaturated or less saturated version of the
wax lipid. The amount of oil present can range from 0 weight
percent to 40 weight percent of the composition, more preferably
from 5 weight percent to 20 weight percent of the composition and
most preferably from 8 weight percent to 15 weight percent of the
composition.
[0055] Contemplated anti-static agents include fabric softeners
which are known to provide antistatic benefits. For example those
fabric softeners that have a fatty acyl group which has an iodine
value of above 20, such as N,N-di(tallowoyl-oxy-ethyl)-N,N-dimethyl
ammonium methylsulfate.
Fibers
[0056] In one embodiment, the fibers may be monocomponent or
multicomponent. The term "fiber" is defined as a solidified polymer
shape with a length to thickness ratio of greater than 1,000. The
monocomponent fibers may also be multiconstituent. Constituent, as
used herein, is defined as meaning the chemical species of matter
or the material. Multiconstituent fiber, as used herein, is defined
to mean a fiber containing more than one chemical species or
material. Multiconstituent and alloyed polymers have the same
meaning herein and can be used interchangeably. Generally, fibers
may be of monocomponent or multicomponent types. Component, as used
herein, is defined as a separate part of the fiber that has a
spatial relationship to another part of the fiber. The term
multicomponent, as used herein, is defined as a fiber having more
than one separate part in spatial relationship to one another. The
term multicomponent includes bicomponent, which is defined as a
fiber having two separate parts in a spatial relationship to one
another. The different components of multicomponent fibers are
arranged in substantially distinct regions across the cross-section
of the fiber and extend continuously along the length of the fiber.
Methods for making multicomponent fibers are well known in the art.
Multicomponent fiber extrusion was well known in the 1960's. DuPont
was a lead technology developer of multicomponent capability, with
U.S. Pat. No. 3,244,783 and U.S. Pat. No. 3,704,971 providing a
technology description of the technology used to make these fibers.
"Bicomponent Fibers" by R. Jeffries from Merrow Publishing in 1971
laid a solid groundwork for bicomponent technology. More recent
publications include "Taylor-Made Polypropylene and Bicomponent
Fibers for the Nonwoven Industry," Tappi Journal December 1991 (p
103) and "Advanced Fiber Spinning Technology" edited by Nakajima
from Woodhead Publishing.
[0057] The nonwoven fabric disclosed herein may contain multiple
types of monocomponent fibers that are delivered from different
extrusion systems through the same spinneret. The extrusion system,
in this example, is a multicomponent extrusion system that delivers
different polymers to separate capillaries. For instance, one
extrusion system would deliver polypropylene with wax and the other
a polypropylene copolymer such that the copolymer composition melts
at different temperatures. In a second example, one extrusion
system might deliver a polyethylene resin and the other
polypropylene with wax. In a third example, one extrusion system
might deliver a polypropylene resin with 30 weight percent wax and
the other a polypropylene resin with 30 weight percent wax that has
a molecular weight different from the first polypropylene resin.
The polymer ratios in this system can range from 95:5 to 5:95,
preferably from 90:10 to 10:90 and 80:20 to 20:80.
[0058] Bicomponent and multicomponent fibers may be in a
side-by-side, sheath-core (symmetric and eccentric), segmented pie,
ribbon, islands-in-the-sea configuration, or any combination
thereof. The sheath may be continuous or non-continuous around the
core. Non-inclusive examples of exemplarily multicomponent fibers
are disclosed in U.S. Pat. No. 6,746,766. The ratio of the weight
of the sheath to the core is from about 5:95 to about 95:5. The
fibers disclosed herein may have different geometries that include,
but are not limited to; round, elliptical, star shaped, trilobal,
multilobal with 3-8 lobes, rectangular, H-shaped, C-shaped,
I-shape, U-shaped and other various eccentricities. Hollow fibers
can also be used. Preferred shapes are round, trilobal and
H-shaped. The round and trilobal fiber shapes can also be
hollow.
[0059] Sheath and core bicomponent fibers are preferred. In one
preferred case, the component in the core may contain the
thermoplastic polymer and wax, while the sheath does not. In this
case the exposure to wax at the surface of the fiber is reduced or
eliminated. In another preferred case, the sheath may contain the
wax and the core does not. In this case the concentration of wax at
the fiber surface is higher than in the core. Using sheath and core
bicomponeut fibers, the concentration of the wax can be selected to
impart desired properties either in the sheath or core, or some
concentration gradient. It should be understood that
islands-in-a-sea bicomponent fibers are considered to be a type of
sheath and core fiber, but with multiple cores. Segmented pie
fibers (hollow and solid) are contemplated. For one example, to
split regions that contain wax from regions that do not contain wax
using segmented pie type of bicomponeut fiber design. Splitting may
occur during mechanical deformation, application of hydrodynamic
forces or other suitable processes.
[0060] Tricomponent fibers are also contemplated. One example of a
useful tricomponent fiber would be a three layered
sheath/sheath/core fiber, where each component contains a different
amount of wax. Different amounts of wax in each layer may provide
additional benefits. For example, the core can be a blend of 10
melt flow polypropylene with 30 weight percent wax. The middle
layer sheath may be a blend of 25 melt flow polypropylene with 20
weight percent wax and the outer layer may be straight 35 melt flow
rate polypropylene. It is preferred that the wax content between
each layer is less than 40 wt %, more preferably less than 20 wt %.
Another type of useful tricomponent fiber contemplated is a
segmented pie type bicomponent design that also has a sheath.
[0061] A "highly attenuated fiber" is defined as a fiber having a
high draw down ratio. The total fiber draw down ratio is defined as
the ratio of the fiber at its maximum diameter (which is typically
results immediately after exiting the capillary) to the final fiber
diameter in its end use. The total fiber draw down ratio will be
greater than 1.5, preferable greater than 5, more preferably
greater than 10, and most preferably greater than 12. This is
necessary to achieve the tactile properties and useful mechanical
properties.
[0062] The fiber will have a diameter of less than 50 .mu.m. The
diameter of the fibers made with any of the previously discussed
compositions can be as low as 0.1 .mu.m if the mixture is being
used to produce fine fibers. The fibers can be either essentially
continuous or essentially discontinuous. Fibers commonly used to
make spunbond nonwovens that are made with any of the previously
discussed compositions will have a diameter of from 5 .mu.m to 30
.mu.m, more preferably from 10 .mu.m to 20 .mu.m and most preferred
from 12 .mu.m to about 18 .mu.m. Fine fiber diameter will have a
diameter from 0.1 .mu.m to 5 .mu.m, preferably from 0.2 .mu.m to 3
.mu.m and most preferred from 0.3 .mu.m to 2 .mu.m Fiber diameter
is controlled by die geometry, spinning speed or drawing speed,
mass through-put, and blend composition and theology. The fibers as
described herein can be environmentally degradable.
[0063] The fibers described herein are typically used to make
disposable articles that include at least one layer of fibers made
with any of the compositions previously discussed, and which can be
in the form of a nonwoven material. The articles can be flushable.
The term "flushable" as used herein refers to materials which are
capable of dissolving, dispersing, disintegrating, and/or
decomposing in a septic disposal system such as a toilet to provide
clearance when flushed down the toilet without clogging the toilet
or any other sewage drainage pipe. The fibers and resulting
articles may also be aqueous responsive. The term aqueous
responsive as used herein means that when placed in water or
flushed, an observable and measurable change will result. Typical
observations include noting that the article swells, pulls apart,
dissolves, or observing a general weakened structure.
[0064] The hydrophilicity and hydrophobicity of the fibers can be
adjusted as needed. The base resin properties can have hydrophilic
properties via copolymerization (such as the case for certain
polyesters (EASTONE from Eastman Chemical, the sulfopolyester
family of polymers in general) or polyolefins such as polypropylene
or polyethylene) or have materials added to the base resin to
render it hydrophilic. Exemplarily examples of additives include
CIBA Irgasurf.RTM. family of additives. The fibers in the present
invention can also be treated or coated after they are made to
render them hydrophilic. In the present invention, durable
hydrophilicity is preferred. Durable hydrophilicity is defined as
maintaining hydrophilic characteristics after more than one fluid
interaction. For example, if the sample being evaluated is tested
for durable hydrophilicity, water can be poured on the sample and
wetting observed. If the sample wets out it is initially
hydrophilic. The sample is then completely rinsed with water and
dried. The rinsing is best done by putting the sample in a large
container and agitating for ten seconds and then drying. The sample
after drying should also wet out when contacted again with
water.
[0065] After the fiber is formed, the fiber may further be treated
or the bonded fabric can be treated. A hydrophilic or hydrophobic
finish can be added to adjust the surface energy and chemical
nature of the fabric. For example, fibers that are hydrophobic may
be treated with wetting agents to facilitate absorption of aqueous
liquids. A bonded fabric can also be treated with a topical
solution containing surfactants, pigments, slip agents, salt, or
other materials to farther adjust the surface properties of the
fiber.
[0066] In one embodiment, the fibers can be crimped, although it
can be preferred that they are not crimped. Crimped fibers are
generally produced in two methods. The first method is mechanical
deformation of the fiber after it is already spun. Fibers are melt
spun, drawn down to the final filament diameter and mechanically
treated, generally through gears or a staffer box that imparts
either a two dimensional or three dimensional crimp. This method is
used in producing most carded staple fibers. The second method for
crimping fibers is to extrude multicomponent fibers that are
capable of crimping in a spunlaid process. One of ordinary skill in
the art would recognize that a number of methods of making
bicomponent crimped spunbond fibers exists; however, three main
techniques are considered for making crimped spunlaid nonwovens.
The first is crimping that occurs in the spinline due to
differential polymer crystallization in the spinline, a result of
differences in polymer type, polymer molecular weight
characteristics (e.g., molecular weight distribution) or additives
content. A second method is differential shrinkage of the fibers
after they have been spun into a spunlaid substrate. For instance,
heating the spunlaid web can cause fibers to shrink due to
differences in crystallinity in the as-spun fibers, for example
during the thermal bonding process. A third method of causing
crimping is to mechanically stretch the fibers or spunlaid web
(generally for mechanical stretching the web has been bonded
together). The mechanical stretching can expose differences in the
stress-strain curve between the two polymer components, which can
cause crimping.
[0067] The tensile strength of a fiber is approximately greater
than 25 Mega Pascal (MPa). The fibers as disclosed herein have a
tensile strength of greater than about 50 MPa, preferably greater
than about 75 MPa, and more preferably greater than about 100 MPa.
Tensile strength is measured using an Instron following a procedure
described by ASTM standard D 3822-91 or an equivalent test.
[0068] The fibers as disclosed herein are not brittle and have a
toughness of greater than 2 MPa, greater than 50 MPa, or greater
than 100 MPa. Toughness is defined as the area under the
stress-strain curve where the specimen gauge length is 25 mm with a
strain rate of 50 mm per minute. Elasticity or extensibility of the
fibers may also be desired.
[0069] The fibers as disclosed herein can be thermally bondable if
sufficient thermoplastic polymers are present in the fiber or on
the outside component of the fiber (i.e. sheath of a bicomponent).
Thermally bondable fibers are best used in the pressurized heat and
thru-air beat bonding methods. Thermally bondable is typically
achieved when the composition is present at a level of greater than
about 15%, preferably greater than about 30%, most preferably
greater than about 40%, and most preferably greater than about 50%
by weight of the fiber.
[0070] The fibers disclosed herein can be environmentally
degradable depending upon the amount of the composition that is
present and the specific configuration of the fiber.
"Environmentally degradable" is defined as being biodegradable,
disintigratable, dispersible, flushable, or compostable or a
combination thereof. The fibers, nonwoven webs, and articles can be
environmentally degradable. As a result, the fibers may be easily
and safely disposed of either in existing composting facilities or
may be flushable and can be safely flushed down the drain without
detrimental consequences to existing sewage infrastructure systems.
The flushability of the fibers when used in disposable products
such as wipes and feminine hygiene items offer additional
convenience and discretion to the consumer.
[0071] The term "biodegradable" refers to matter that, when exposed
to an aerobic and/or anaerobic environment, is eventually reduced
to monomeric components due to microbial, hydrolytic, and/or
chemical, actions. Under aerobic conditions, biodegradation leads
to the transformation of the material into end products such as
carbon dioxide and water. Under anaerobic conditions,
biodegradation leads to the transformation of the materials into
carbon dioxide, water, and methane. The biodegradability process is
often described as mineralization. Biodegradability means that all
organic constituents of the matter (e.g., fibers) are subject to
decomposition eventually through biological activity.
[0072] There are a variety of different standardized
biodegradability methods that have been established over time by
various organizations and in different countries. Although the
tests vary in the specific testing conditions, assessment methods,
and criteria desired, there is reasonable convergence between
different protocols so that they are likely to lead to similar
conclusions for most materials. For aerobic biodegrability, the
American Society for Testing and Materials (ASTM) has established
ASTM D 5338-92: Test methods for Determining Aerobic Biodegradation
of Plastic Materials under Controlled Composting Conditions. The
ASTM test measures the percent of test material that mineralizes as
a function of time by monitoring the amount of carbon dioxide being
released as a result of assimilation by microorganisms in the
presence of active compost held at a thermophilic temperature of
58.degree. C. Carbon dioxide production testing may be conducted
via electrolytic respirometry. Other standard protocols, such 301B
from the Organization for Economic Cooperation and Development
(OECD), may also be used. Standard biodegradation tests in the
absence of oxygen are described in various protocols such as ASTM D
5511-94. These tests are used to simulate the biodegradability of
materials in an anaerobic solid-waste treatment facility or
sanitary landfill. However, these conditions are less relevant for
the type of disposable applications that are described for the
fibers and nonwovens as described herein.
[0073] Disintegration occurs when the fibrous substrate has the
ability to rapidly fragment and break down into fractions small
enough not to be distinguishable alter screening when composted or
to cause drainpipe clogging when flushed. A disintegratable
material will also be flushable. Most protocols for
disintegradability measure the weight loss of test materials over
time when exposed to various matrices. Both aerobic and anaerobic
disintegration tests are used. Weight loss is determined by the
amount of fibrous test material that is no longer collected on an
18 mesh sieve with 1 millimeter openings after the materials is
exposed to wastewater and sludge. For disintegration, the
difference in the weight of the initial sample and the dried weight
of the sample recovered on a screen will determine the rate and
extent of disintegration. The testing for biodegradability and
disintegration are very similar as a very similar environment, or
the same environment, will be used for testing. To determine
disintegration, the weight of the material remaining is measured
while for biodegradability, the evolved gases are measured. The
fibers disclosed herein can rapidly disintegrate.
[0074] The fibers as disclosed herein can also be compostable. ASTM
has developed test methods and specifications for compostability.
The test measures three characteristics: biodegradability,
disintegration, and lack of ecotoxicity. Tests to measure
biodegradability and disintegration are described above. To meet
the biodegradability criteria for compostability, the material
roust achieve at least about 60% conversion to carbon dioxide
within 40 days. For the disintegration criteria, the material must
have less than 10% of the test material remain on a 2 millimeter
screen in the actual shape and thickness that it would have in the
disposed product. To determine the last criteria, lack of
ecotoxicity, the biodegradation byproducts must not exhibit a
negative impact on seed germination and plant growth. One test for
this criteria is detailed in OECD 208. The International
Biodegradable Products Institute will issue a logo for
compostability once a product is verified to meet ASTM 6400-99
specifications. The protocol follows Germany's DIN 54900 which
determine the maximum thickness of any material that allows
complete decomposition within one composting cycle.
[0075] The fibers described herein can be used to make disposable
nonwoven articles. The articles are commonly flushable. The term
"flushable" as used herein refers to materials which are capable of
dissolving, dispersing, disintegrating, anchor decomposing in a
septic disposal system such as a toilet to provide clearance when
flushed down the toilet without clogging the toilet or any other
sewage drainage pipe. The fibers and resulting articles may also be
aqueous responsive. The term aqueous responsive as used herein
means that when placed in water or flushed, an observable and
measurable change will result. Typical observations include noting
that the article swells, pulls apart, dissolves, or observing a
general weakened structure.
[0076] The nonwoven products produced from the fibers exhibit
certain mechanical properties, particularly, strength, flexibility,
softness, and absorbency. Measures of strength include dry and/or
wet tensile strength. Flexibility is related to stiffness and can
attribute to softness. Softness is generally described as a
physiologically perceived attribute which is related to both
flexibility and texture. Absorbency relates to the products'
ability to take up fluids as well as the capacity to retain
them.
Configuration of the Fibers
[0077] The fibers disclosed herein can also be splittable fibers.
Rheological, thermal, and solidification differential behavior can
potentially cause splitting. Splitting may also occur by a
mechanical means such as ring rolling, stress or strain, use of an
abrasive, or differential stretching, and/or by fluid induced
distortion, such as hydrodynamic or aerodynamic.
[0078] For a bicomponent fiber, a composition as disclosed herein
can be both the sheath and the core with one of the components
containing more wax and/or additives than the other component.
Alternatively, the composition disclosed herein can be the sheath
with the core being some other materials, e.g., pure polymer. The
composition can alternatively be the core with the sheath being
some other polymer, e.g., pure polymer. The exact configuration of
the fiber desired is dependent upon the use of the fiber.
Processes of Making the Compositions as Disclosed Herein
[0079] Melt mixing of the polymer and wax: The polymer and wax can
be suitably mixed by melting the polymer in the presence of the
wax. In the melt state, the polymer and wax are subjected to shear
which enables a dispersion of the oil into the polymer. In the melt
state, the wax and polymer are significantly more compatible with
each other.
[0080] The melt mixing of the polymer and wax can be accomplished
in a number of different processes, but processes with high shear
are preferred to generate the preferred morphology of the
composition. The processes can involve traditional thermoplastic
polymer processing equipment. The general process order involves
adding the polymer to the system, melting the polymer, and then
adding the wax. However, the materials can be added in any order,
depending on the nature of the specific mixing system.
[0081] Haake Batch Mixer: A Haake Batch mixer is a simple mixing
system with low amount of shear and mixing. The unit is composed of
two mixing screws contained within a heated, fixed volume chamber.
The materials are added into the top of the unit as desired. The
preferred order is to add the polymer, heat to 20.degree. C. to
120.degree. C. above the polymer's melting (or solidification)
temperature into the chamber first. Once the polymer is melted, the
wax can be added and mixed with the molten polymer once the wax
melts. The mixture is then mixed in the melt with the two mixing
screws for about 5 to about 15 minutes at screw RPM from about 60
to about 120. Once the composition is mixed, the front of the unit
is removed and the mixed composition is removed in the molten
state. By its design, this system leaves parts of the composition
at elevated temperatures before crystallization starts for several
minutes. This mixing process provides an intermediate quenching
process, where the composition can take about 30 seconds to about 2
minutes to cool down and solidify. Mixture of polypropylene with
hydrogenated soy bean oil in the Haake mixture shows that greater
than 20 wt % of molten wax leads to incomplete incorporation of the
wax in the polypropylene mixture, indicating that higher shear
rates can lead to better incorporation of wax and greater amounts
of wax able to be incorporated.
[0082] Single Screw Extruder: A single screw extruder is a typical
process unit used in most molten polymer extrusion. The single
screw extruder typically includes a single shaft within a barrel,
the shaft and barrel engineered with certain screw elements (e.g.,
shapes and clearances) to adjust the shearing profile. A typical
RPM range for single screw extruder is about 10 to about 120. The
single screw extruder design is composed of a feed section,
compression section and metering section. In the feed section,
using fairly high void volume flights, the polymer is heated and
supplied into the compression section, where the melting is
completed and the fully molten polymer is sheared. In the
compression section, the void volume between the flights is
reduced. In the metering section, the polymer is subjected to its
highest shearing amount using low void volume between flights. For
this work, general purpose single screw designs were used. In this
unit, a continuous or steady state type of process is achieved
where the composition components are introduced at desired
locations, and then subjected to temperatures and shear within
target zones. The process can be considered to be a steady state
process as the physical nature of the interaction at each location
in the single screw process is constant as a function of time. This
allows for optimization of the mixing process by enabling a
zone-by-zone adjustment of the temperature and shear, where the
shear can be changed through the screw elements and/or barrel
design or screw speed.
[0083] The mixed composition exiting the single screw extruder can
then be pelletized via extrusion of the melt into a liquid cooling
medium, often water, and then the polymer strand can be cut into
small pieces or pellets. Alternatively, the mixed composition can
be used to produce the final formed structure, for example fibers.
There are two basic types of molten polymer pelletization process
used in polymer processing: strand cutting and underwater
pelletization. In strand cutting the composition is rapidly
quenched (generally much less than 10 seconds) in the liquid medium
then cut into small pieces. In the underwater pelletization
process, the molten polymer is cut into small pieces then
simultaneously or immediately thereafter placed in the presence of
a low temperature liquid which rapidly quenches and crystallizes
the polymer. These methods are commonly known and used within the
polymer processing industry.
[0084] The polymer strands that come from the extruder are rapidly
placed into a water bath, most often having a temperature range of
1.degree. C. to 50.degree. C. (e.g., normally is about room
temperature, which is 25.degree. C.). An alternate end use for the
mixed composition is further processing into the desired structure,
for example fiber spinning, films or injection molding. The single
screw extrusion process can provide for a high level of mixing and
high quench rate. A single screw extruder also can be used to
further process a pelletized composition into fibers and injection
molded articles. For example, the fiber single screw extruder can
be a 37 mm system with a standard general purpose screw profile and
a 30:1 length to diameter ratio.
[0085] Twin Screw Extruder: A twin screw extruder is the typical
unit used in most molten polymer extrusion, where high intensity
mixing is required. The twin screw extruder includes two shafts and
an outer barrel. A typical RPM range for twin screw extruder is
about 10 to about 1200. The two shafts can be co-rotating or
counter rotating and allow for close tolerance, high intensity
mixing. In this type of unit, a continuous or steady state type of
process is achieved where the composition components are introduced
at desired locations along the screws, and subjected to high
temperatures and shear within target zones. The process can be
considered to be a steady state process as the physical nature of
the interaction at each location in the single screw process is
constant as a function of time. This allows for optimization of the
mixing process by enabling a zone-by-zone adjustment of the
temperature and shear, where the shear can be changed through the
saw elements and/or barrel design.
[0086] The mixed composition at the end of the twin screw extruder
can then be pelletized via extrusion of the melt into a liquid
cooling medium, often water, and then the polymer strand is cut
into small pieces or pellets. Alternatively, the mixed composition
can be used to produce the final formed structure, for example
fibers. There are two basic types of molten polymer pelletization
process, strand cutting and underwater pelletization, used in
polymer processing. In strand cutting the composition is rapidly
quenched (generally much less than 10s) in the liquid medium then
cut into small pieces. In the underwater pelletization process, the
molten polymer is cut into small pieces then simultaneously or
immediately thereafter placed in the presence of a low temperature
liquid which rapidly quenches and crystallizes the polymer. An
alternate end use for the mixed composition is direct further
processing into filaments or fibers via spinning of the molten
admixture accompanied by cooling.
[0087] Three different screw profiles can be employed using a Baker
Perkins CT-25 25 mm corotating 40:1 length to diameter ratio
system. This specific CT-25 is composed of nine zones where the
temperature can be controlled, as well as the die temperature. Four
liquid injection sites as also possible, located between zone 1 and
2 (location A), zone 2 and 3 (location B), zone 4 and 5 (location
C), and zone 6 and 7 (location D).
[0088] The liquid injection location is not directly healed, but
indirectly through the adjacent zone temperatures. Locations A, B,
C and D can be used to inject the additive. Zone 6 can contain a
side feeder for adding additional solids or used for venting. Zone
8 contains a vacuum for removing any residual vapor, as needed.
Unless noted otherwise, the melted wax is injected at location A.
The wax is melted via a glue tank and supplied to the twin-screw
via a heated hose. Both the glue tank and the supply hose are
heated to a temperature greater than the melting point of the wax
(e.g., about 80.degree. C.).
[0089] Two types of regions, conveyance and mixing, are used in the
CT-25. In the conveyance region, the materials are heated
(including through melting which is done in Zone 1 into Zone 2 if
needed) and conveyed along the length of the barrel, under low to
moderate shear. The mixing section contains special elements that
dramatically increase shear and mixing. The length and location of
the mixing sections can be changed as needed to increase or
decrease shear as needed.
[0090] Two primary types of mixing elements are used for shearing
and mixing. The first are kneading blocks and the second are
thermal mechanical energy elements. The simple mixing screw has
10.6% of the total screw length using mixing elements composed of
kneading blocks in a single set followed by a reversing element.
The kneading elements are RKB 45/5/12 (right handed forward
kneading block with 45.degree. offset and five lobes at 12 mm total
element length), followed by two RKB 45/5/36 (right handed forward
kneading block with 45.degree. offset and five lobes at 36 mm total
element length), that is followed by two RKB 45/5/12 and reversing
element 24/12 LH (left handed reversing element 24 mm pitch at 12
mm total element length).
[0091] The Simple mixing screw mixing elements are located in zone
7. The Intensive screw is composed of additional mixing sections,
four in total. The first section is single set of kneading blocks
is a single element of RKB45/5/36 (located in zone 2) followed by
conveyance elements into zone 3 where the second mixing zone is
located. In the second mixing zone, two RKB 45/5/36 elements are
directly followed by four TME 22.5/12 (thermomechanical element
with 22.5 teeth per revolution and total element length of 12 mm)
then two conveyance elements into the third mixing area. The third
mixing area, located at the end of zone 4 into zone 5, is composed
of three RKB 45/5/36 and a KB45/5/12 LH (left handed forward
reversing block with 45.degree. offset and five lobes at 12 mm
total element length. The material is conveyed through zone 6 into
the final mixing area comprising two TME 22.5/12, seven RKB
45/5/12, followed by SB 24/12 LH. The SB24/32 LH is a reversing
element that enables the last mixing zone to be completely filled
with polymer and additive, where the intensive mixing takes place.
The reversing elements can control the residence time in a given
mixing area and are a key contributor to the level of mixing.
[0092] The High Intensity mixing screw is composed of three mixing
sections. The first mixing section is located in zone 3 and is two
RKB45/5/36 followed by three TME 22.5/12 and then conveyance into
the second mixing section. Prior to the second mixing section three
RSE 16/16 (right handed conveyance element with 16 mm pitch and 16
mm total element length) elements are used to increase pumping into
the second mixing region. The second mixing region, located in zone
5, is composed of three RKB 45/5/36 followed by a KB 45/5/12 LH and
then a full reversing element SE 24/12 LH. The combination of the
SB 16/16 elements in front of the mixing zone and two reversing
elements greatly increases the shear and mixing. The third mixing
zone is located in zone 7 and is composed of three RKB 45/5/12,
followed by two TME 22.5.12 and then three more RKB45/5/12. The
third mixing zone is completed with a reversing element SB 24/12
LH.
[0093] An additional screw element type is a reversing element,
which can increase the filling level in that part of the screw and
provide better mixing. Twin screw compounding is a mature field.
One skilled in the art can consult books for proper mixing and
dispersion. These types of screw extruders are well understood in
the art and a general description can be found in: Twin Screw
Extrusion 2E: Technology and Principles by James White from Hansen
Publications. Although specific examples are given for mixing, many
different combinations are possible using various element
configurations to achieve the needed level of mixing.
Properties of Compositions
[0094] The compositions as disclosed herein can have one or more of
the following properties that provide an advantage over known
thermoplastic compositions. These benefits can be present alone or
in a combination.
[0095] Shear Viscosity Reduction: As shown in FIG. 1, addition of
the wax, e.g., HSBO, to the thermoplastic polymer, e.g., Basell
PH-835, reduces the viscosity of the thermoplastic polymer (here,
polypropylene in the presence of the molten HSBO wax). Viscosity
reduction is a process improvement as it can allow for effectively
higher polymer flow rates by having a reduced process pressure
(lower shear viscosity), or can allow for an increase in polymer
molecular weight, which improves the material strength. Without the
presence of the wax, it may not be possible to process the polymer
with a high polymer flow rate at existing process conditions in a
suitable way.
[0096] Sustainable Content: Inclusion of sustainable materials into
the existing polymeric system is a strongly desired property.
Materials that can be replaced every year through natural growth
cycles contribute to overall lower environmental impact and ate
desired.
[0097] Pigmentation: Adding pigments to polymers often involves
using expensive inorganic compounds that are particles within the
polymer matrix. These particles are often large and can interfere
in the processing of the composition. Using a wax as disclosed
herein, because of the fine dispersion (as measured by droplet
size) and uniform distribution throughout the thermoplastic polymer
allows for coloration, such as via traditional ink compounds. Soy
ink is widely used in paper publication) that does not impact
processability.
[0098] Fragrance: Because the waxes, for example HSBO, can contain
perfumes much more preferentially than the base thermoplastic
polymer, the present composition can be used to contain scents that
are beneficial for end-use. Many scented caudles are made using SBO
based or paraffin based materials, so incorporation of these into
the polymer for the final composition is useful.
[0099] Surface Feel: The presence of the wax can change the surface
properties of the composition, compared to a thermoplastic polymer
composition without a wax, making it feel softer.
[0100] Morphology: The benefits are delivered via the morphology
produced in production of the compositions. The morphology is
produced by a combination of intensive mixing and rapid
crystallization. The intensive mixing comes from the compounding
process used and rapid crystal ligation comes from the cooling
process used. High intensity mixing is desired and rapid
crystallization is used to preserves die fine pore size and
relatively uniform pore size distribution. FIG. 2 shows HSBO in
Basell Profax PH-835, with the small pore sizes of less than 10
.mu.m, less than 5 .mu.m, and less than 1 .mu.m.
[0101] Improved Spinning Performance: Adding the wax has shown to
improve spinning of fibers, enabling a finer diameter filament to
be achieved vs the neat polymer the additive has been admixed into
during composition preparation.
Processes for Making Fibers
[0102] Fibers can be spun from a melt of the compositions as
disclosed herein. In melt spinning, there is no mass loss in the
extrudate. Melt spinning is differentiated from other spinning,
such as wet or dry spinning from solution, where a solvent is being
eliminated by volatilizing or diffusing out of the extrudate
resulting in a mass loss.
[0103] Spinning can occur at 120.degree. C. to about 320.degree.
C., preferably 185.degree. C. to about 250.degree. C. and most
preferably from 200.degree. C. to 230.degree. C. Fiber spinning
speeds of greater than 100 meters/minute are preferred. Preferably,
the fiber spinning speed is about 1,000 to about 10,000
meters/minute, more preferably about 2,000 to about 7,000
meters/minute, and most preferably about 2,500 to about 5,000
meters/minute. The polymer composition is spun fast to avoid
brittleness in the fiber.
[0104] Continuous filaments or fibers can be produced through
spunbond methods. Essentially continuous or essentially
discontinuous filaments or fibers can be produced through melt
fibrillation methods such as meltblowing or melt film fibrillation
processes. Alternatively, non-continuous (staple fibers) fibers can
be produced. The various methods of fiber manufacturing can also be
combined to produce a combination technique.
[0105] The homogeneous blend can be melt spun into monocomponent or
multicomponent fibers on conventional melt spinning equipment. The
equipment will be chosen based on the desired configuration of the
multicomponent. Commercially available melt spinning equipment is
available from Hills, Inc. located in Melbourne, Fla. The
temperature for spinning is about 100.degree. C. to about
320.degree. C. The processing temperature is determined by the
chemical nature, molecular weights and concentration of each
component. The fibers spun can be collected using conventional
godet winding systems or through air drag attenuation devices. If
the godet system is used, the fibers can be further oriented
through post extrusion drawing at temperatures of about 25.degree.
C. to about 200.degree. C. The drawn fibers may then be crimped
and/or cut to form non-continuous fibers (staple fibers) used in a
carding, airlaid, or fluidlaid process.
[0106] For example, a suitable process for spinning bicomponent
sheath core fibers using the composition in the sheath and a
different composition in the core is as follows. A composition is
first prepared through compounding containing 10wt % HSBO and a
second composition is first prepared through compounding containing
30wt % HSBO. The 10 wt % HSBO component extruder profile may be
180.degree. C., 200.degree. C. and 220.degree. C. in the first
three zones of a three heater zone extruder. The transfer lines and
melt pump heater temperatures may be 220.degree. C. for the first
composition. The second composition extruder temperature profile
can be 180.degree. C., 230.degree. C. and 230.degree. C. in the
first three zones of a three heater zone extruder. The transfer
lines and melt pump can be heated to 230.degree. C. In this case,
the spinneret temperature can be 220.degree. C. to 230.degree.
C.
Fine Fiber Production
[0107] In one embodiment, the homogenous blend is spun into one or
more filaments or fibers by melt film fibrillation. Suitable
systems and melt film fibrillation methods are described in U.S.
Pat. Nos. 6,315,806, 5,183,670, and 4,536,361, to Torobin et al.,
and U.S. Pat. Nos. 6,382,526, 6,520,425, and 6,695,992, to Reneker
et al. and assigned to the University of Akron. Other melt film
fibrillation methods and systems are described in the U.S. Pat.
Nos. 7,666,343 and 7,931,457, to Johnson, et al., U.S. Pat. No.
7,628,941, to Krause et al., and U.S. Pat. No. 7,722,347, to
Krause, et al. Methods and apparatus described in above patents
provide nonwoven webs with uniform and narrow fiber distribution,
reduced or minimal fiber defects. Melt trim fibrillation process
comprises providing one or more melt films of the homogenous blend,
one or more pressurized fluid streams (or fiberizing fluid streams)
to fibrillate the melt film into ligaments, which are attenuated by
the pressurized fluid stream. Optionally, one or more pressurized
fluid streams maybe provided to aid the attenuation and quenching
of the ligaments to form fibers. Fibers produced from the melt film
fibrillation process using one of embodiment homogenous blend would
have diameters typically ranging from about 100 nanometer (0.1
micrometer) to about 5000 nanometer (5 micrometer). In one
embodiment, the fibers produced from the melt film fibrillation
process of the homogenous blend would be less than 2 micrometer,
more preferably less than 1 micrometer (1000 nanometer), and most
preferably in the range of 100 nanometer (0.1 micrometer) to about
900 nanometer (0.9 micrometer). The average diameter (an arithmetic
average diameter of at least 100 fiber samples) of fibers of the
homogenous blend produced using the melt film fibrillation would be
less than 2.5 micrometer, more preferably less than 1 micrometer,
and most preferably less than 0.7 micrometer (700 nanometer). The
median fiber diameter can be 1 micrometer or less. In an
embodiment, at least 50% of the fibers of the homogenous blend
produced by the melt film fibrillation process may have diameter
less than 1 micrometer, more preferably, at least 70% of the fibers
may have diameter less than 1 micrometer, and most preferably, at
least 90% of the fibers may have diameter less than 1 micrometer.
In certain embodiments, even 99% or more fibers may have diameter
less than 1 micrometer when produced using the melt film
fibrillation process.
[0108] In the melt film fibrillation process, the homogenous blend
is typically heated until it forms a liquid and flows easily. The
homogenous blend may be at a temperature of from about 120.degree.
C. to about 350.degree. C. at the time of melt film fibrillation,
in one embodiment from about 160.degree. C. to about 350.degree.
C., and in another embodiment from about 200.degree. C. to about
300.degree. C. The temperature of the homogenous blend depends on
the composition. The heated homogenous blend is at a pressure from
about 15 pounds per square inch absolute (psia) to about 400 psia,
in another embodiment from about 20 psia to about 200 psia, and in
yet another embodiment from about 25 psia to about 100 psia.
[0109] Non-limiting examples of the pressurized fiberizing fluid
stream are gases such as air or nitrogen or any other fluid
compatible (defined as reactive or inert) with homogenous blend
composition. The fiberizing fluid stream can be at a temperature
close to the temperature of the heated homogenous blend. The
fiberizing fluid stream temperature may be at a higher temperature
than the heated homogenous blend to help in the flow of the
homogenous blend and the formation of the melt film. In one
embodiment, the fiberizing fluid stream temperature is about
100.degree. C. above the heated homogenous blend, in another
embodiment about 50.degree. C. above the heated homogenous blend,
or just at temperature of the heated homogenous blend.
Alternatively, the fiberizing fluid stream temperature can be below
the heated homogenous blend temperature. In one embodiment, the
fiberizing fluid stream temperature is about 50.degree. C. below
the heated homogenous blend, in another embodiment about
100.degree. C. below the heated homogenous blend, or 200.degree. C.
below heated homogenous blend. In certain embodiments, the
temperature of the fiberizing fluid stream may be ranging from
about -100.degree. C. to about 450.degree. C., more preferably,
ranging from about -50.degree. C. to 350.degree. C., and most
preferably, ranging from about 0.degree. C. to about 300.degree. C.
The pressure of the fiberizing fluid stream is sufficient to
fibrillate the homogenous blend into fibers, and is above the
pressure of the heated homogenous blend. The pressure of the
fiberizing fluid stream may range from about 15 psia to about 500
psia, more preferably from about 30 psia to about 200 psia, and
most preferably from about 40 psia to about 100 psia. The
fiberizing fluid stream may have a velocity of more than about 200
meter per second at the location of melt film fibrillation. In one
embodiment, at the location of melt film fibrillation, the
fiberizing fluid stream velocity will be more than about 300 meter
per second, i.e., transonic velocity; in another embodiment more
than about 330 meter per second, i.e., sonic velocity; and in yet
another embodiment from about 350 to about 900 meters per second
(m/s), i.e., supersonic velocity from about Mach 1 to Mach 3. The
fiberizing fluid stream may pulsate or may be a steady flow. The
homogenous blend throughput will primarily depend upon the specific
homogenous blend used, the apparatus design, and the temperature
and pressure of the homogenous blend. The homogenous blend
throughput will be more than about 1 gram per minute per orifice,
for example in a circular nozzle. In one embodiment, the homogenous
blend throughput will be more than about 10 gram per minute per
orifice and in another embodiment greater than about 20 gram per
minute per orifice, and in yet another embodiment greater than
about 30 gram per minute per orifice. In an embodiment with the
slot nozzle, the homogenous blend throughput will be more than
about 0.5 kilogram per hour per meter width of the slot nozzle. In
another slot nozzle embodiment, the homogenous blend throughput
will be mote than about 5 kilogram per hour per meter width of the
slot nozzle, and in another slot nozzle embodiment, the homogenous
blend throughput will be more than about 20 kilogram per hour per
meter width of the slot nozzle, and in yet another slot nozzle
embodiment, the homogenous blend throughput will be more than about
40 kilogram per hour per meter width of the slot nozzle. In certain
embodiments of the slot nozzle, the homogenous blend throughput may
exceed about 60 kilogram per hour per meter width of the slot
nozzle. There will likely be several orifices or nozzles operating
at one time which further increases the total production
throughput. The throughput, along with pressure, temperature, and
velocity, are measured at the orifice or nozzle for both circular
and slot nozzles.
[0110] Optionally, an entraining fluid can be used to induce a
pulsating or fluctuating pressure field to help in forming fibers.
Non-limiting examples of the entraining fluid are pressurized gas
stream such as compressed air, nitrogen, oxygen, or any other fluid
compatible (defined as reactive or inert) with the homogenous blend
composition. The entertaining fluid with a high velocity can have a
velocity near sonic speed (i.e. about 330 m/s) or supersonic speeds
(i.e. greater than about 330 m/s). An entraining fluid with a low
velocity will typically have a velocity of from about 1 to about
100 m/s and in another embodiment from about 3 to about 50 m/s. It
is desirable to have low turbulence in the entraining fluid stream
14 to minimize fiber-to-fiber entanglements, which usually occur
due to high turbulence present in the fluid stream. The temperature
of the entraining fluid 14 can be the same as the above fiberizing
fluid scream, or a higher temperature to aid quenching of
filaments, and ranges from about -40.degree. C. to 40.degree. C.
and in another embodiment from about 0.degree. C. to about
25.degree. C. The additional fluid stream may form a "curtain" or
"shroud" around the filaments exiting from the nozzle. Any fluid
stream may contribute to the fiberization of the homogenous blend
and can thus generally be called fiberizing fluid stream.
[0111] The spunlaid processes disclosed herein use a high speed
spinning process as disclosed in U.S. Pat. Nos. 3,802,317;
5,545,371; 6,548,431 and 5,885,909. In these melt spinning
processes, extruders supply molten polymer to melt pumps, which
deliver specific volumes of molten polymer that transfer through a
spinpack, composed of a multiplicity of capillaries formed into
fibers, where the fibers are cooled through an air quenching zone
and are pneumatically drawn down to reduce their size into highly
attenuated fibers to increase fiber strength through molecular
level fiber orientation. The drawn fibers are then deposited onto a
porous belt, often referred to as a forming belt or forming
table.
Spunlaid Process
[0112] The fibers forming the base substrate disclosed herein are
preferably continuous filaments forming spunlaid fabrics. Spunlaid
fabrics are defined as unbonded fabrics having basically no
cohesive tensile properties formed from essentially continuous
filaments. Continuous filaments are defined as fibers with high
length to diameter ratios, with a ratio of more than 10,000:1.
Continuous filaments that compose the spunlaid fabric are not
staple fibers, short cut fibers or other intentionally made short
length fibers. The continuous filaments, defined as essentially
continuous, are on average, more than 100 mm long, preferably more
than 200 mm long. The continuous filaments are also not crimped,
intentionally or unintentionally. Essentially discontinuous fibers
and filaments are defined as having a length less than 100 mm long,
preferably less than 50 mm long.
[0113] The spunlaid processes can use a high speed spinning process
as disclosed in U.S. Pat. Nos. 3,802,817; 5,545,371; 6,548,431 and
5,885,909. In these melt spinning processes, extruders supply
molten polymer to melt pumps, which deliver specific volumes of
molten polymer that transfer through a spinpack, composed of a
multiplicity of capillaries formed into fibers, where the fibers
are cooled through an air quenching zone and are pneumatically
drawn down to reduce their size into highly attenuated fibers to
increase fiber strength through molecular level fiber orientation.
The drawn fibers are then deposited onto a porous belt, often
referred to as a forming belt or forming table.
[0114] In one embodiment, the spunlaid process used to make the
continuous filaments will contain 100 to 10,000 capillaries per
meter, preferably 200 to 7,000 capillaries per meter, more
preferably 500 to 5,000 capillaries per meter. The polymer mass
flow rate per capillary in the present invention will be greater
than 0.3 GHM (grams per hole per minute). The preferred range is
from 0.35 GHM to 2 GHM, preferably between 0.4 GHM and 1 GHM, still
mote preferred between 0.45 GHM and 8 GHM and the most preferred
range from 0.5 GHM to 0.6 GHM.
[0115] The spunlaid process can contain a single process step tor
making the highly attenuated, uncrimped continuous filaments.
Extruded filaments are drawn through a zone of quench air where
they are cooled and solidified as they are attenuated. Such
spunlaid processes are disclosed in U.S. Pat. No. 3,338,992, U.S.
Pat. No. 3,802,817, U.S. Pat. No. 4,233,014 U.S. Pat. No.
5,688,468, U.S. Pat. No. 6,548,431B1, U.S. Pat. No. 6,908,292B2 and
U.S. Application 2007/0057414A1. The technology described in EP
1340843B1 and EP 1323852B1 can also be used to produce the spunlaid
nonwovens. The highly attenuated continuous filaments are directly
drawn down from the exit of the polymer from the spinneret to the
attenuation device, wherein the continuous filament diameter or
denier does not change substantially as the spunlaid fabric is
formed on the forming table
[0116] Preferred polymeric materials include, but are not limited
to, polypropylene and polypropylene copolymers, polyethylene and
polyethylene copolymers, polyester and polyester copolymers,
polyamide, polyimide, polylactic acid, polyhydroxyalkaonate,
polyvinyl alcohol, ethylene vinyl alcohol, polyacrylates, and
copolymers thereof and mixtures thereof, as well as the other
mixture disclosed herein. Other suitable polymeric materials
include thermoplastic starch compositions as described in detail in
U.S. publications 2003/0109605A1 and 2003/0091803. Still other
suitable polymeric materials include ethylene acrylic acid,
polyolefin carboxylic acid copolymers, and combinations thereof.
The polymers described in U.S. Pat. No. 6,746,766, U.S. Pat. No.
6,818,295, U.S. Pat. No. 6,946,506 and U.S. Published Application
03/0092343. Common thermoplastic polymer fiber grade materials are
preferred, most notably polyester based resins, polypropylene based
resins, polylactic acid based resin, polyhydroxyalkonoate based
resin, and polyethylene based resin and combination thereof. Most
preferred are polyester and polypropylene based resins.
[0117] It should also be noted that the ability to utilize mixture
compositions above 40 weigh percent (wt %) wax in the extrusion
process, where the masterbatch level of wax is combined with a
lower concentration (down to 0 wt %) thermoplastic composition
during extrusion to produce a wax content within the target
range.
[0118] In the process of spinning fibers, particularly as the
temperature is increased above 105.degree. C., typically it is
desirable for residual water levels to be 1%, by weight of the
fiber, or less, alternately 0.5% or less, or 0.15% or less.
Articles
[0119] The fibers can be converted to nonwovens by different
bonding methods. Continuous fibers can be formed into a web using
industry standard spunbond type technologies while staple fibers
can be formed into a web using industry standard carding, airlaid,
or wetlaid technologies. Typical bonding methods include: calender
(pressure and heat), thru-air heat, mechanical entanglement,
hydrodynamic entanglement, needle punching, and chemical bonding
and/or resin bonding. The calender, thru-air heat, and chemical
bonding are the preferred bonding methods for the starch polymer
fibers. Thermally bondable fibers are required for the pressurized
beat and thru-air heat bonding methods.
[0120] The fibers that are made with any of the compositions
discussed herein may also be bonded or combined with other
synthetic or natural fibers to make disposable articles. The
synthetic or natural fibers may be blended together in the forming
process or used in discrete layers. Suitable synthetic fibers
include fibers made from polypropylene, polyethylene, polyester,
polyacrylates, and copolymers thereof and mixtures thereof. Natural
fibers include cellulosic fibers and derivatives thereof. Suitable
cellulosic fibers include those derived from any tree or
vegetation, including hardwood fibers, softwood fibers, hemp, and
cotton. Also included are fibers made from processed natural
cellulosic resources such as rayon.
[0121] The fibers that are made with any of the compositions
discussed herein may be used to make one or more layers of nonwoven
that can then be used to make a disposable article. The nonwoven
described herein may be combined with additional nonwovens or films
to produce a laminate used either by itself or as a component in a
complex combination of other materials, such as a baby diaper or
feminine care pad. Disposable articles that may benefit from the
use of the fibers and nonwovens described herein include disposable
absorbent articles such as baby diapers, training pants, adult
incontinence articles, panty liners, sanitary napkins, tampons,
absorbent pads (such as the SWIFFER WET and SWIFFER WETJET pads). A
typical absorbent article that may include at least one layer of a
nonwoven comprising fibers that are made with any of the
compositions discussed herein is schematically represented in FIG.
3. The disposable absorbent article 10 includes a liquid pervious
layer 110, a liquid impervious layer 210 and an absorbent core 310
disposed between the liquid pervious and impervious layers. In one
embodiment, fibers that are made with any of the compositions
discussed herein are included (preferably in the form of a nonwoven
layer) in at least one of the liquid pervious layer, the liquid
impervious layer, and the absorbent core of a disposable absorbent
article. In another embodiment, fibers that are made with any of
the compositions discussed herein are included in at least one of
the layers that form a cleaning wipe suitable to cleaning soft or
hard surfaces. Other disposable articles include filters for air,
oil and water; vacuum cleaner filters; furnace filters; face masks;
coffee filters, tea or coffee bags; thermal insulation materials
and sound insulation materials. The fibrous web may also include
odor absorbents, termite repellants, insecticides, rodenticides,
and the like, for specific uses. The resultant product absorbs
water and oil and may find use in oil or water spill clean-up, or
controlled water retention and release for agricultural or
horticultural applications. The resultant fibers or fiber webs may
also be incorporated into other materials such as saw dust, wood
pulp, plastics, and concrete, to form composite materials, which
can be used as building materials such as walls, support beams,
pressed boards, dry walls and backings, and ceiling tiles; other
medical uses such as casts, splints, and tongue depressors; and in
fireplace logs for decorative and/or burning purpose.
EXAMPLES
[0122] Polymers: The primary polymers used in this work are
polypropylene (PP) and polyethylene (PE), but other polymers can be
used (see, e.g., U.S. Pat. No. 6,783,854, which provides a
comprehensive list of polymers that are possible, although not all
have been tested). Specific polymers evaluated were:
[0123] Basell Profax PH-835: Produced by Lyondell-Basell as
nominally a 35 melt flow rate Ziegler-Natta isotactic
polypropylene.
[0124] Exxon Achieve 3854: Produced by Exxon-Mobil Chemical as
nominally a 25 melt flow rate metallocene isotactic
polypropylene.
[0125] Total 8650: Produced by Total Chemicals as a nominally 10
melt flow rate Ziegler-Natta isotactic ethylene random copolymer
polypropylene.
[0126] Danimer 27510: Proprietary polyhydroxyalkanoate
copolymer.
[0127] Dow Aspun 6811A: Produced by Dow Chemical as a 27 melt index
polyethylene copolymer.
[0128] BASF Ultramid B27: Produced by BASF as a low viscosity
polyamide-6 resin.
[0129] Eastman 9921: Produced by Eastman Chemical as a copolyester
terephthalic homopolymer with a nominally 0.81 intrinsic
viscosity.
[0130] Natureworks Ingeo Biopolymer 4032D: Produced by Natureworks
as polylactic acid polymer.
[0131] Waxes: Specific examples used were: Hydrogenated Soy Bean
Oil (HSBO); Partially Hydrogenated Soy Bean Oil (HSBO); Partially
Hydrogenated Palm Kernel Oil (PKPKO); a commercial grade soy bean
oil based--wax candle with pigmentation and fragrance; standard
green Soy Beats Green Ink Pigment
[0132] Compositions were made using a Baker Perkins CT-25 Screw,
with the zones set as noted in the below table:
TABLE-US-00001 TABLE 1 Ratio Twin-Screw Temperature Profile
(.degree. C.) Polymer Wax Polymer Wax Z1 Z2 Z3 Z4 Z5 Z6 Z7 1 PH-835
HSBO 90 10 40 160 180 200 200 200 210 2 PH-835 HSBO 80 20 40 160
180 200 200 200 210 3 PH-835 HSBO 70 30 40 160 180 200 200 200 210
4 Achieve 3854 HSBO 90 10 40 160 180 200 200 200 210 5 Achieve 3854
HSBO 80 20 40 160 180 200 200 200 210 6 Achieve 3854 HSBO 70 30 40
160 180 200 200 200 210 7 PH-835 PHSBO 90 10 40 160 180 200 200 200
210 8 PH-835 PHSBO 80 20 40 160 180 200 200 200 210 9 PH-835 PHSBO
70 30 40 160 180 200 200 200 210 10 Achieve 3854 PHSBO 90 10 40 160
180 200 200 200 210 11 Achieve 3854 PHSBO 80 20 40 160 180 200 200
200 210 12 Achieve 3854 PHSBO 70 30 40 160 180 200 200 200 210 13
PH-835 HSBO 90 10 40 160 180 240 240 240 240 14 PH-835 HSBO 80 20
40 160 180 240 240 240 240 15 PH-835 HSBO 70 30 40 160 180 240 240
240 240 16 PH-835 HSBO 60 40 40 160 180 240 240 240 240 17 Total
8650 HSBO 60 40 40 160 180 240 240 240 240 18 PH-835 HSBO 60 40 40
160 180 260 260 260 260 19 Total 8650 HSBO 60 40 40 160 180 260 260
260 260 20 Total 8650 HSBO 90 10 40 160 180 200 200 200 210 21
Total 8650 HSBO 80 20 40 160 180 200 200 200 210 22 Total 8650 HSBO
70 30 40 160 180 200 200 200 210 23 PH-835 PHPKO 70 30 40 160 180
200 200 200 210 24 Danimer 27510 HSBO 95 5 40 170 180 180 180 180
180 25 Danimer 27510 HSBO 93 7 40 170 180 180 180 180 180 26
Danimer 27510 HSBO 90 10 40 170 180 180 180 180 180 27 Danimer
27510 HSBO 85 15 40 170 180 180 180 180 180 28 Aspun 6811A HSBO 90
10 40 160 180 190 190 190 190 29 Aspun 6811A HSBO 80 20 40 160 180
190 190 190 190 30 Aspun 6811A HSBO 70 30 40 160 180 190 190 190
190 31 Aspun 6811A HSBO 60 40 40 160 180 190 190 190 190 32 Aspun
6811A HSBO 50 50 40 160 180 190 190 190 190 33 Natureworks 4032D
HSBO 95 5 40 160 180 190 190 190 190 34 Natureworks 4032D HSBO 90
10 40 160 180 190 190 190 190 35 Ultramid B27 HSBO 90 10 40 220 240
250 260 270 270 36 Ultramid B27 HSBO 85 15 40 220 240 250 260 270
270 37 Ultramid B27 HSBO 80 20 40 220 240 250 260 270 270 38
Eastman 9921 HSBO 95 5 40 220 260 270 290 290 290 39 Eastman 9921
HSBO 92 8 40 220 260 270 290 290 290 40 Eastman 9921 HSBO 90 10 40
220 260 270 290 290 290 41 Eastman 9921 HSBO 85 15 40 220 260 270
290 290 290 42 PH-835 HSBO 70 30 40 160 180 240 240 240 240 43
PH-835 HSBO 70 30 40 160 180 240 240 240 240 44 CP-360H HSBO 90 10
40 160 180 200 200 200 210 45 CP-360H HSBO 85 15 40 160 180 200 200
200 210 46 CP-360H HSBO 80 20 40 160 180 200 200 200 210 Poly Wax
Twin-Screw Temperature Profile (.degree. C.) Temp Temp Screw Screw
Torque Z8 Z9 Die (.degree. C.) (.degree. C.) RPM Type (%) 1 210 210
170 216 80 400 Intensive 56 2 210 210 170 216 80 400 Intensive 43 3
210 210 170 217 80 400 Intensive 30 4 210 210 170 220 80 500
Intensive 50 5 210 210 170 215 80 500 Intensive 41 6 210 210 170
218 80 500 Intensive 30 7 210 210 170 202 80 400 Intensive 60 8 210
210 170 199 80 400 Intensive 44 9 210 210 170 201 80 400 Intensive
39 10 210 210 170 204 80 500 Intensive 5 11 210 210 170 202 80 500
Intensive 44 12 210 210 170 205 80 500 Intensive 38 13 210 210 170
NR 80 400 High NR 14 210 210 170 176 80 400 High 45 15 210 210 170
173 80 400 High 37 16 210 210 170 176 80 400 High 31 17 210 210 170
178 80 600 High 27 18 210 210 170 176 80 400 High 25 19 210 210 170
179 80 600 High 27 20 210 210 170 184 80 600 High 51 21 210 210 170
185 80 600 High 41 22 210 210 170 182 80 600 High 32 23 210 210 170
203 80 400 High 43 24 180 180 170 164 80 400 High 27 25 180 180 170
165 80 400 High 26 26 180 180 170 167 80 400 High 25 27 180 180 170
NR 80 400 High NR 28 190 190 170 173 80 500 High 55 29 190 190 170
170 80 500 High 46 30 190 190 170 170 80 500 High 39 31 190 190 170
171 80 500 High 30 32 190 190 170 173 80 500 High 23 33 190 190 170
175 80 600 High 47 34 190 190 170 NR 80 500 High NR 35 260 250 240
238 80 600 High 47 36 260 250 240 NR 80 600 High NR 37 260 250 240
NR 80 600 High NR 38 290 280 250 262 80 400 High 59 39 290 280 250
264 80 600 High 61 40 290 280 250 264 80 600 High 59 41 290 280 250
264 80 600 High 59 42 210 210 170 174 80 400 High 28 43 210 210 170
174 80 400 High 28 44 210 210 170 172 80 500 High 63 45 210 210 170
170 80 500 High 57 46 210 210 170 171 80 500 High 52
[0133] Examples 1-26 and 42-46 were made using polypropylene
resins, while examples 27-41 were made using other types of
thermoplastic polymer resins. All examples successfully formed
pellets, except examples 34, 37 and 44. A slight excess of the wax
was noted for examples 9, 12, and 27, e.g., small amounts of
surging were noted at the outlet of the twin-screw, but not
sufficient to break the strand and disrupt the process. The slight
excess of wax indicates that the level of mixing is insufficient at
that level or the polymer/wax composition is close to saturation.
Examples 43 and 44 also included an added pigment and perfume to
the wax.
[0134] Examples 1-46 show the polymer plus additive tested in a
stable range and to the limit. As used herein, stable refers to the
ability of the composition to be extruded and to be pelletized.
What was observed was that during the stable composition, strands
from the B & P 25 mm system could be extruded, quenched in a
water bath at 5.degree. C. and cut via a pelletizer without
interruption. The twin-screw extrudate was immediately dropped into
the water bath.
[0135] During stable extrusion, no significant amount of wax
separated from the formulation strand (>99wt % made it through
the pelletizer). Saturation of the composition can be noted by
separation of the polymer and wax from each other at the end of the
twin-screw. The saturation point of the wax in the composition can
change based on the wax and polymer combination, along with the
process conditions. The practical utility is that the wax and
polymer remain admixed and do not separate, which is a function of
the mixing level and quench rate for proper dispersion of the
additive. Specific Examples where the extrusion became unstable
from high wax inclusion are Example 34, 37, and 41.
[0136] Example 42 was processed using 30 wt % HSBO plus the
addition of a scent and pigment (e.g., Febreze Rosewood scent and
pigmented candle). One candle was added per 20lb of wax into the
glue tank and stirred manually. The candle wick was removed before
addition. The candle contained both a pigment and perfume that were
present in the as-formed pellets of the composition at the end of
the process. Example 43 was identical to Example 42 except the
vacuum was turned on to determine how much perfume or volatiles
could be removed. No difference between as-formed pellets of
Example 42 and Example 43 could be observed.
[0137] Examples 1-45 show the polymer plus additive tested in a
stable range and to the limit. As used herein, stable refers to the
ability of the composition to be extruded and to be pelletized.
What was observed was that during the stable composition, strands
from the B & P 25 mm system could be extruded, quenched in a
water bath at 5.degree. C. and cut via a pelletizer without
interruption. The twin-screw extrudate was immediately dropped into
the water bath. During stable extrusion, no significant amount of
oil separated from the formulation strand (>99 wt % made it
through the pelletizer). The composition became unstable when it
was clear that the polymer and oil were separating from each other
at the end of the twin-screw and the composition strands could not
be maintained. Without being bound by theory, the polymer at this
point is considered fully saturated. The saturation point can
change based on the oil and polymer combination, along with the
process conditions. The practical utility is that the oil and
polymer remain admixed and do not separate, which is a function of
the mixing level and quench rate for proper dispersion of the
additive. Specific Examples where the extrusion became unstable
from high oil inclusion are Example 5, 7, 10, 12, 16 and 42.
[0138] Fibers can be produced by melt spinning a composition of any
one of Examples 1-45. Fibers were melt spun with several
composition examples.
[0139] The specific melt spinning equipment was a specially
designed bicomponent extrusion system that consists of two single
extruders, followed by a melt pump after each extruder. The two
melt streams are combined into a sheath/core spinpack purchased
from Hills Inc. The spinpack had 144 holes with capillary orifice
diameter of 0.35 mm. The fibers extruded through the spinpack were
quenched on two sides using a 1 m long quench system that blows
air. The fibers are attenuated using a high pressure aspirator that
draws the filaments down. The as-spun fibers were deposited onto a
belt and collected to measure the final as-spun filament diameter.
The as-spun filament diameter is an average of 10 measurements made
under a light microscope. The reported fiber diameter is the
minimum fiber diameter that could be achieved without any filament
breaks over five minutes for the entire 144 filaments being
extruded. The mass throughput used was 0.5 grams per capillary per
minute (ghm). The specific fibers made and the processes for making
them are shown in Table 2.
TABLE-US-00002 TABLE 2 Temperature Profiles (.degree. C.) Final
Sheath Extruder Core Extruder Dia- Trans- Trans- Beam meter Sheath
Core Sheath Core fer fer Spin- (mi- Examples Material Material
Ratio Ratio Z1 Z2 Z3 Z4 Line Z1 Z2 Z3 Z4 Line pack cron) PH-835
PH-835 PH-835 30 70 180 200 220 230 230 180 200 220 230 230 230 17
CP360H CP360H CP360H 30 70 180 200 220 230 230 180 200 220 230 230
230 18 47 PH-835 Example 1 30 70 180 200 220 230 230 180 200 220
230 230 230 16 48 Example 1 Example 1 30 70 180 200 220 230 230 180
200 220 230 230 230 15* 49 PH-835 Example 2 30 70 180 200 220 230
230 180 200 220 230 230 230 16 50 Example 2 Example 2 30 70 180 200
220 230 230 180 200 220 230 230 230 15* 51 PH-835 Example 3 30 70
180 200 220 230 230 180 200 220 230 230 230 15 52 Example 3 Example
3 30 70 180 200 220 230 230 180 200 220 230 230 230 15* 53 PH-835
Example 4 30 70 180 200 220 230 230 180 200 220 230 230 230 17 54
Example 4 Example 4 30 70 180 200 220 230 230 180 200 220 230 230
230 15* 55 PH-835 Example 5 30 70 180 200 220 230 230 180 200 220
230 230 230 17 56 Example 5 Example 5 30 70 180 200 220 230 230 180
200 220 230 230 230 15* 57 PH-835 Example 24 30 70 180 200 220 230
230 180 200 220 230 230 230 17 58 Example 24 Example 24 30 70 180
200 220 230 230 180 200 220 230 230 230 16* 59 PH-835 Example 25 30
70 180 200 220 230 230 180 200 220 230 230 230 18 60 Example 25
Example 25 30 70 180 200 220 230 230 180 200 220 230 230 230 16
8650 8650 8650 30 70 180 200 220 230 230 180 200 220 230 230 230 20
61 Example 11 Example 11 30 70 180 200 220 230 230 180 200 220 230
230 230 15 62 PH-835 Example 8 30 70 180 200 220 230 230 180 200
220 230 230 230 15 63 Example 47 Example 47 30 70 180 200 220 230
230 180 200 220 230 230 230 16 64 Example 48 Example 48 30 70 180
200 220 230 230 180 200 220 230 230 230 16 65 Example 49 Example 49
30 70 180 200 220 230 230 180 200 220 230 230 230 15 *denotes could
not reach fiber spinning failure at maximum draw down pressure
[0140] Examples 47-65 show the results from producing useful fibers
and the benefit of improved spinnability by adding wax. The
examples show that utilizing polypropylene with wax in the core or
into the sheath and core improve the spinnability and enable finer
filaments to be produced. Finer fibers can improve softness,
barrier properties and wicking behavior.
[0141] Spunbond nonwovens were made by using the porous collection
belt and adjusting the belt speed to target 20 grams per square
meter (gsm). The collected fibers were first passed through a
heated press roll at 100.degree. C. at 50 PLI (pounds per linear
inch) and then a heated calendering system for the final thermal
point bonding, followed by winding the continuous spunbond nonwoven
onto a roll for later property measurements. The heated calendering
system consisted of a heated engraved roll and heated smooth roll.
The heated engraved roll bad 18% raised bonding area. The calender
roll pressure was held constant at 350 PLI and the line speed of
the forming belt was held constant at 38 meters per minute.
[0142] The tensile properties of base substrates and structured
substrates were all measured the sane way. The gauge width is 50
mm, gauge length is 100 mm in the MD and 50 mm in the CD and the
extension rate is 100 mm/min. The values reported are for strength
and elongation at peak, unless stated otherwise. Separate
measurements are made for the MD and CD properties. The typical
units are Newton (N), and they are Newtons per centimeter (N/cm).
The values presented are the average of at least ten measurements.
The perforce load is 0.2 N. The samples should be stored at
23.+-.2.degree. C. and at 50.+-.2% relative humidity for 24 hours
with no compression, then tested at 23.+-.2.degree. C. and at
50.+-.2%. The tensile strength as reported here is the peak tensile
strength in the stress-strain curve. The elongation at tensile peak
is the percent elongation at which the tensile peak is
recorded.
[0143] Examples 66-105 show that useful spunbond nonwovens can be
produced. The specifies of Examples 64-103 are shown in Table 3.
The examples show that an optimum bonding temperature is to achieve
at a particular fiber composition.
TABLE-US-00003 TABLE 3 Average MD Tensile CD Tensile Strength
Temperature (.degree. C.) Basis Peak Elon- Peak Elon- Exam- Sheath
Core Fiber Engraved Smooth Wt Ld St. gation St. Ld St. gation ple
Material Material Example Roll Roll (gsm) (N) Dev (%) Dev (N) Dev
(%) 66 CP360H CP360H CP360H 115 110 19.9 25.7 1.5 19 2 13.1 1.9 28
67 CP360H CP360H CP360H 120 115 19.6 26.8 2.6 22 3 13.2 1.9 27 68
CP360H CP360H CP360H 125 120 20.3 31 1.7 26 3 14.5 2.6 30 69 CP360H
CP360H CP360H 130 125 19.5 37 1.7 34 3 16.1 2.3 35 70 CP360H CP360H
CP360H 135 130 20.4 41.4 1.8 40 3 19.3 1.3 42 71 CP360H CP360H
CP360H 140 135 20.5 46.1 3.8 42 7 23.8 2.4 52 72 CP360H CP360H
CP360H 145 140 19.7 41.2 4.9 32 8 21.9 3.5 49 73 CP360H CP360H
CP360H 150 145 20.3 34.4 5.6 19 5 22.9 2.9 43 74 CP360H CP360H
CP360H 155 150 21 25.2 2.5 10 2 13.6 1.5 27 CP360H 75 CP360H CP360H
CP360H 160 155 20.5 17.9 3.8 6 1 10.3 1.9 20 76 Example 47 Example
47 Example 66 115 110 22.3 19.6 1.6 18 2 7 1 25 77 Example 47
Example 47 Example 66 120 115 21.7 21.7 1.3 21 2 8 1 28 10% SBO 78
Example 47 Example 47 Example 66 125 120 21.4 24.3 1.9 26 3 10 1 32
79 Example 47 Example 47 Example 66 130 125 21.8 28.4 2 36 4 13 2
44 80 Example 47 Example 47 Example 66 135 130 21.6 38.4 2.8 51 7
17 2 58 81 Example 47 Example 47 Example 66 140 135 22.1 42.5 3.3
55 7 21 2 62 82 Example 47 Example 47 Example 66 145 140 22.5 43.1
2.9 48 8 25 2 73 83 Example 47 Example 47 Example 66 150 145 22.9
38.4 3.1 31 5 23 3 52 84 Example 47 Example 47 Example 66 155 150
22.5 30.6 3 17 3 16 2 28 85 Example 47 Example 47 Example 66 160
155 21.9 25.7 1.7 11 2 16 1 28 86 Example 47 Example 47 Example 66
165 160 23.6 22.6 1.9 9 2 12 2 11 87 Example 48 Example 48 Example
67 115 110 23.7 26.9 2 26 2 9 1 35 88 Example 48 Example 48 Example
67 120 115 22.2 27.5 1.8 31 3 10 1 34 89 Example 48 Example 48
Example 67 125 120 23.3 32.4 1.1 36 2 13 1 47 90 Example 48 Example
48 Example 67 130 125 22.6 37.2 1.5 43 2 15 1 55 91 Example 48
Example 48 Example 67 135 130 22.7 42.4 2.5 55 7 18 2 69 92 Example
48 Example 48 Example 67 140 135 23 45.3 2.7 52 7 21 2 78 93
Example 48 Example 48 Example 67 145 140 24.2 41.9 3.7 40 8 24 3 76
15% SBO 94 Example 48 Example 48 Example 67 150 145 26.1 38.3 1.7
25 3 20 2 51 95 Example 49 Example 49 Example 68 115 110 22.2 22.8
1.6 31 3 7 1 42 20% SBO 96 Example 49 Example 49 Example 68 120 115
21.9 23.8 1.3 34 4 8 1 45 97 Example 49 Example 49 Example 68 125
120 21.4 26.8 1.3 39 3 11 1 55 98 Example 49 Example 49 Example 68
130 125 21.1 28.4 1.2 44 4 13 1 68 99 Example 49 Example 49 Example
68 135 130 20.9 30 2.2 44 5 15 2 82 100 Example 49 Example 49
Example 68 140 135 22.4 31.6 2.3 43 7 18 2 92 101 Example 49
Example 49 Example 68 145 140 21.9 30.1 3.1 35 7 16 6 81 102
Example 49 Example 49 Example 68 150 145 21 26.2 1.2 23 4 15 1 59
103 Example 49 Example 49 Example 68 155 150 22.2 23.3 0.8 15 3 13
2 43 104 Example 49 Example 49 Example 68 160 155 22.7 24 1.7 14 2
12 1 36 105 Example 49 Example 49 Example 68 165 160 23.9 17.9 1.4
7 2 9 1 29
[0144] 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". Every
document cited herein, including any cross referenced or related
patent or application, 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.
[0145] While particular embodiments of the 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.
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