U.S. patent application number 13/635144 was filed with the patent office on 2013-01-10 for process for making nonwoven webs.
Invention is credited to Robert John Duff, John C Howe, Zheng-Zheng Huang, Lakshmi Krishnamurthy, David Matthews Laura, JR., Joel M Pollino, Michael T Pottiger, Joachim C Ritter, Harry Vaughn Samuelson, Zuohong Yin.
Application Number | 20130009333 13/635144 |
Document ID | / |
Family ID | 44673808 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130009333 |
Kind Code |
A1 |
Krishnamurthy; Lakshmi ; et
al. |
January 10, 2013 |
PROCESS FOR MAKING NONWOVEN WEBS
Abstract
A nonwoven web comprising bicomponent fibers. The fibers have
continuous phases each of a first polyarylene sulfide (PAS)
component and a polymer component. The polymer component may also
be a second polyarylene sulfide. The first polyarylene sulfide
component contains a tin or a zinc additive or both, and the first
polyarylene sulfide component of any given fiber is at least
partially exposed to the external surface of that fiber.
Inventors: |
Krishnamurthy; Lakshmi;
(Wilmington, DE) ; Yin; Zuohong; (West Chester,
PA) ; Ritter; Joachim C; (Wilmington, DE) ;
Pollino; Joel M; (Alpharetta, GA) ; Pottiger; Michael
T; (Media, PA) ; Howe; John C; (Bear, DE)
; Laura, JR.; David Matthews; (Midlothian, VA) ;
Samuelson; Harry Vaughn; (Chadds Ford, PA) ; Duff;
Robert John; (Newark, DE) ; Huang; Zheng-Zheng;
(Wilmington, DE) |
Family ID: |
44673808 |
Appl. No.: |
13/635144 |
Filed: |
March 17, 2011 |
PCT Filed: |
March 17, 2011 |
PCT NO: |
PCT/US11/28752 |
371 Date: |
September 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61316065 |
Mar 22, 2010 |
|
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|
Current U.S.
Class: |
264/103 |
Current CPC
Class: |
D04H 3/02 20130101; D01F
8/16 20130101; D04H 1/56 20130101; D01D 5/34 20130101; D01F 1/10
20130101 |
Class at
Publication: |
264/103 |
International
Class: |
D04H 3/16 20060101
D04H003/16 |
Claims
1. A process for manufacturing a nonwoven web comprising the steps
of (i) spinning bicomponent fibers into a nonwoven web, said fibers
comprising continuous phases each of a first polyarylene sulfide
(PAS) component and a polymer component, in which the first
polyarylene sulfide component contains a tin or a zinc additive or
both, and the first polyarylene sulfide component of any given
fiber is at least partially exposed to the external surface of that
fiber, and (ii) calendaring the nonwoven web.
2. The process of claim 1 in which the step of spinning is a
spunbond process.
3. The process of claim 1 in which the polymer component comprises
a polymer selected from the group consisting or polyether ether
ketone (PEEK), polyether ketone (PEK), polyester, polypropylene,
polyamide, and mixtures thereof.
4. The process of claim 3 in which the polyester comprises
polyethylene terephthalate (PET), polytrimethylene terephthalate,
or polybutylene terephthalate (PBT).
5. The process of claim 1 in which the second polymer component
comprises a second polyarylene sulfide.
6. The process of claim 5 in which the second polyarylene sulfide
is blended with a calcium salt.
7. The process of claim 6 in which the calcium salt is calcium
stearate.
8. The process of claim 1 in which the tin additive is a branched
carboxylate selected from the group consisting of
Sn(O.sub.2CR).sub.2, Sn(O.sub.2CR)(O.sub.2CR'),
Sn(O.sub.2CR)(O.sub.2CR''), and mixtures thereof, where the
carboxylate moieties O.sub.2CR and O.sub.2CR' independently
represent branched carboxylate anions and the carboxylate moiety
O.sub.2CR'' represents a linear carboxylate anion
9. The process of claim 8 in which tin additive further comprises a
linear tin(II) carboxylate Sn(O.sub.2CR'').sub.2
10. The process of claim 8 in which the sum of the branched
carboxylate moieties O.sub.2CR and O.sub.2CR' is at least about 25%
on a molar basis of the total carboxylate moieties O.sub.2CR,
O.sub.2CR' and O.sub.2CR'' contained in the tin additive.
11. The process of claim 8 in which the radical R'' is a primary
alkyl group comprising from 6 to 30 carbon atoms.
12. The process of claim 11 in which the radical R'' is substituted
with a group selected form the group consisting of fluoride,
chloride, bromide, iodide, nitro, hydroxyl, carboxylate, and any
combination thereof.
13. The process of claim 8 in which the radicals R and R'
independently or both have a structure represented by Formula (I),
##STR00003## wherein R.sub.1, R.sub.2, and R.sub.3 are selected
from the group consisting of: H; a primary, secondary, or tertiary
alkyl group having from 6 to 18 carbon atoms, optionally
substituted with fluoride, chloride, bromide, iodide, nitro,
hydroxyl, and carboxyl groups; an aromatic group having from 6 to
18 carbon atoms, optionally substituted with alkyl, fluoride,
chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups;
and a cycloaliphatic group having from 6 to 18 carbon atoms,
optionally substituted with fluoride, chloride, bromide, iodide,
nitro, hydroxyl, and carboxyl groups; with the proviso that when
R.sub.2 and R.sub.3 are H, R.sub.1 is: a secondary or tertiary
alkyl group having from 6 to 18 carbon atoms, optionally
substituted with fluoride, chloride, bromide, iodide, nitro,
hydroxyl, and carboxyl groups; an aromatic group having from 6 to
18 carbons atoms and substituted with a secondary or tertiary alkyl
group having from 6 to 18 carbon atoms, the aromatic group and/or
the secondary or tertiary alkyl group being optionally substituted
with fluoride, chloride, bromide, iodide, nitro, hydroxyl, and
carboxyl groups; and a cycloaliphatic group having from 6 to 18
carbon atoms, optionally substituted with fluoride, chloride,
bromide, iodide, nitro, hydroxyl, and carboxyl groups.
14. The process of claim 8 in which the radicals R and R'
independently or both have a structure represented by Formula (I),
and R.sub.3 is H.
15. The process of claim 8 in which the radicals R and R'
independently or both have a structure represented by Formula (II),
##STR00004## wherein R.sub.4 is a primary, secondary, or tertiary
alkyl group having from 4 to 6 carbon atoms, optionally substituted
with fluoride, chloride, bromide, iodide, nitro, and hydroxyl
groups; and R.sub.5 is a methyl, ethyl, n-propyl, sec-propyl,
n-butyl, sec-butyl, or tert-butyl group, optionally substituted
with fluoride, chloride, bromide, iodide, nitro, and hydroxyl
groups.
16. The process of claim 8 in which the radicals R and R' are the
same and both have a structure represented by Formula (II), R.sub.4
is n-butyl, and R.sub.5 is ethyl.
17. The process of claim 1 in which the tin additive is present at
a concentration of about 10 weight percent or less of the weight of
the first polyarylene sulfide component.
18. The process of claim 1 in which the zinc additive comprises a
zinc(II) additive or zinc metal [Zn(O)] or a mixture of both.
19. The process of claim 18 in which the zinc(II) additive is an
organic additive or an inorganic additive or a mixture of both.
20. The process of claim 19, wherein the Zn(II) additive is
selected from the group consisting of zinc oxide, zinc stearate,
zinc sulfate and mixtures thereof.
21. The process of claim 1, wherein the zinc and tin additives are
present at a total concentration of equal to or less than about 25
weight percent, based on the weight of the polyarylene sulfide.
22. The process of claim 21, wherein the Zn(II) additive and zinc
metal are present at a total concentration of zero to about about
10 weight percent or less, based on the weight of the polyarylene
sulfide.
23. The process of claim 5, wherein the first polyarylene sulfide,
or the second polyarylene sulfide, or both are polyphenylene
sulfide.
24. The process of claim 1 comprising calendaring the nonwoven web
for a time and temperature sufficient to bond at least a subset of
the individual fibers.
Description
FIELD
[0001] This invention relates to processes of making nonwoven webs,
and in particular webs formed from polyarylene sulfides.
BACKGROUND
[0002] It is known that physical properties of a web can be
improved by calendaring, which is the process of passing a sheet
material through a nip between rolls or plates to impart a smooth,
glossy appearance to the sheet material or otherwise improving
selected physical properties.
[0003] Through the calendaring of paper or other fibrous materials,
an effort is made to further improve the quality of paper formed
or, in providing a standard level of quality, to achieve a higher
running speed or increased bulk of the paper being produced. It is
well known that the plasticity or molding tendency of paper or
fiber may be increased by raising the temperature and/or the
plasticizer content of the paper or fiber. A considerable change in
mechanical properties, including plasticity, occurs when the
temperature of the polymers contained in the paper rises to or
beyond the so-called glass transition temperature (T.sub.g), at
which point the material may then be more readily molded or formed
or finished than it can below that temperature.
[0004] Many nonwoven fabrics are bonded to impart integrity to the
fabric. While there are several bonding techniques available,
thermal bonding processes prevail in the nonwovens industry both in
volume and time devoted to the research and development of new
products. These processes have gained wide acceptance due to
simplicity and many advantages over traditional chemical bonding
methods. Attractive features include low energy and raw material
costs, increased production rates, and product versatility.
Chemical simplification, since adhesive binders are not used,
reduces concerns over the environment. U.S. Pat. No. 4,035,219 and
U.S. Pat. No. 5,424,115 provide examples of point bonding of
nonwoven webs to enhance physical properties.
[0005] U.S. Pat. No. 2,277,049 to Reed introduced the idea of using
fusible fibers to make nonwoven fabrics by blending fusible and
nonfusible fibers of similar denier and cut length and treating the
web with either solvent or heat. The fusible fibers become tacky
and act as a binder. A nonwoven fabric results after pressing and
cooling the tacky web.
[0006] The use of temperatures near the melting point Tm of the
fiber in a nanoweb is detrimental to the quality of the web. The
small size of the fibers combined with the uneven heating inherent
in calendaring machinery tend to produce uneven melting and bonding
and render the web less effective for filtration and battery
separator and other energy storage applications. The deficiency in
the prior art in the area of strengthening of webs of low basis
weight and comprising fine denier fiber is exemplified in EP 1 042
549, in which thermal bonding in a pattern is used to produce a
less deformable web.
[0007] This invention overcomes the deficiencies in previous
processes for making calendared webs by providing a process that
provides a high strength product under less severe conditions that
heretofore.
SUMMARY
[0008] This invention is directed to a nonwoven web comprising
bicomponent fibers, said fibers comprising continuous phases each
of a first polyarylene sulfide (PAS) component and a polymer
component, in which the first polyarylene sulfide component
contains a tin or a zinc additive or both and the first polyarylene
sulfide component of any given fiber is at least partially exposed
to the external surface of that fiber. By "partially exposed" is
meant that at least a portion, of the component appears on an
outside surface of the fiber. The entire outside surface of the
fiber may be the first PAS component may also at least partially
envelop the polymer component.
[0009] The invention is also directed to an improved process for
manufacturing a nonwoven web comprising the steps of (i) spinning
bicomponent fibers into a nonwoven web, said fibers comprising
continuous phases each of a first polyarylene sulfide component and
a polymer component, in which the first polyarylene sulfide
component contains a tin or a zinc additive or both and the first
polyarylene sulfide component of any given fiber is at least
partially exposed to the external surface of that fiber, and (ii)
calendaring the nonwoven web to bond at least a subset of the
individual fibers. In a particular embodiment, the the nonwoven web
is calendared for a time and temperature sufficient to bond at
least a subset of the individual fibers.
DETAILED DESCRIPTION
[0010] Where the indefinite article "a" or "an" is used with
respect to a statement or description of the presence of a step in
a process of this invention, it is to be understood, unless the
statement or description explicitly provides to the contrary, that
the use of such indefinite article does not limit the presence of
the step in the process to one in number.
[0011] Where a range of numerical values is recited herein, unless
otherwise stated, the range is intended to include the endpoints
thereof, and all integers and fractions within the range. It is not
intended that the scope of the invention be limited to the specific
values recited when defining a range.
Definitions
[0012] As used herein the term "spunbond" refers to small diameter
fibers which are formed by extruding molten thermoplastic material
as filaments from a plurality of fine, usually circular capillaries
of a spinneret with the diameter of the extruded filaments being
rapidly reduced as by for example in U.S. Pat. No. 4,340,563 to
Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S.
Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and
3,341,394 to Kinney, U.S. Pat. No. 3,542,615 to Dobo et al., which
are each incorporated by reference in their entirety herein.
[0013] As used herein, the term "meltblown" means fibers formed by
extruding a molten thermoplastic material through a plurality of
fine, usually circular die capillaries as molten threads or
filaments into converging high velocity gas (e.g. air) streams
which attenuate the filaments of molten thermoplastic material to
reduce their diameter, which may be to microfiber diameter.
Thereafter, the meltblown fibers are carried by the high velocity
gas stream and are deposited on a collecting surface to form a web
of randomly dispersed meltblown fibers. Such a process is
disclosed, in various patents and publications, including NRL
Report 4364, "Manufacture of Super-Fine Organic Fibers" by B. A.
Wendt, E. L. Boone and D. D. Fluharty; NRL Report 5265, "An
Improved Device For The Formation of Super-Fine Thermoplastic
Fibers" by K. D. Lawrence, R. T. Lukas, J. A. Young; and U.S. Pat.
No. 3,849,241, issued Nov. 19, 1974, to Butin, et al, which patent
is incorporated by reference hereto in its entirety.
[0014] As used herein the term "multicomponent fibers" refers to
fibers which have been formed from at least two component polymers,
or the same polymer with different properties or additives,
extruded from separate extruders but spun together to form one
fiber. Multicomponent fibers are also sometimes referred to as
conjugate fibers or bicomponent fibers. The polymers are arranged
in substantially constantly positioned distinct zones across the
cross-section of the multicomponent fibers and extend continuously
along the length of the multicomponent fibers. The configuration of
such a multicomponent fiber may be, for example, a sheath/core
arrangement wherein one polymer is surrounded by another, or may be
a side by side arrangement, an "islands-in-the-sea" arrangement, or
arranged as pie-wedge shapes or as stripes on a round, oval, or
rectangular cross-section fiber. Multicomponent fibers are taught
in, for example, U.S. Pat. No. 5,108,820 to Kaneko et al., U.S.
Pat. No. 5,336,552 to Strack et al., and U.S. Pat. No. 5,382,400 to
Pike et al. For two component fibers, the polymers may be present
any desired ratios.
[0015] As used herein the term "biconstituent fiber" or
"multiconstituent fiber" refers to a fiber formed from at least two
polymers, or the same polymer with different properties or
additives, extruded from the same extruder as a blend and wherein
the polymers are not arranged in substantially constantly
positioned distinct zones across the cross-section of the
multicomponent fibers. Fibers of this general type are discussed
in, for example, U.S. Pat. No. 5,108,827 to Gessner.
[0016] As used herein the term "nonwoven web" or "nonwoven
material" means a web having a structure of individual fibers or
filaments which are interlaid, but not in an identifiable manner as
in a knitted or woven fabric. Nonwoven webs have been formed from
many processes such as for example, meltblowing processes,
spunbonding processes, air-laying processes and carded web
processes. The basis weight of nonwoven fabrics is usually
expressed in grams per square meter (gsm) or ounces of material per
square yard (osy) and the fiber diameters useful are usually
expressed in microns. (Note that to convert from osy to gsm,
multiply osy by 33.91).
[0017] By "partially envelops" is meant that that one component in
a bicomponent or multicomponent fiber at least partially encloses a
second component. One component may also appear on the external
surface of the fiber.
[0018] "Calendering" is the process of passing a web through a nip
between two rolls. The rolls may be in contact with each other, or
there may be a fixed or variable gap between the roll surfaces.
Advantageously, in the present calendering process, the nip is
formed between a soft roll and a hard roll. The "soft roll" is a
roll that deforms under the pressure applied to keep two rolls in a
calender together. The "hard roll" is a roll with a surface in
which no deformation that has a significant effect on the process
or product occurs under the pressure of the process. The hard roll
may have a pattern engraved on it or it may be unpatterned. An
"unpatterned" roll is one which has a smooth surface within the
capability of the process used to manufacture them. There are no
points or patterns to deliberately produce a pattern on the web as
it passed through the nip, unlike a point bonding roll.
[0019] Polyarylene sulfides (PAS) include linear, branched or cross
linked polymers that include arylene sulfide units. Polyarylene
sulfide polymers and their synthesis are known in the art and such
polymers are commercially available.
[0020] Exemplary polyarylene sulfides useful in the invention
include polyarylene thioethers containing repeat units of the
formula
--[(Ar.sup.1).sub.n--X].sub.m--[(Ar.sup.2).sub.i--Y].sub.j--(Ar.sup.3).su-
b.k-Z].sub.l--[(Ar.sup.4).sub.o-W].sub.p-- wherein Ar.sup.1,
Ar.sup.2, Ar.sup.3, and Ar.sup.4 are the same or different and are
arylene units of 6 to 18 carbon atoms; W, X, Y, and Z are the same
or different and are bivalent linking groups selected from
--SO.sub.2--, --S--, --SO--, --CO--, --O--, --COO-- or alkylene or
alkylidene groups of 1 to 6 carbon atoms and wherein at least one
of the linking groups is --S--; and n, m, i, j, k, l, o, and p are
independently zero or 1, 2, 3, or 4, subject to the proviso that
their sum total is not less than 2. The arylene units Ar.sup.1,
Ar.sup.2, Ar.sup.3, and Ar.sup.4 may be selectively substituted or
unsubstituted. Advantageous arylene systems are phenylene,
biphenylene, naphthylene, anthracene and phenanthrene. The
polyarylene sulfide typically includes at least 30 mol %,
particularly at least 50 mol % and more particularly at least 70
mol arylene sulfide (--S--) units. Preferably the polyarylene
sulfide polymer includes at least 85 mol % sulfide linkages
attached directly to two aromatic rings. Advantageously the
polyarylene sulfide polymer is polyphenylene sulfide (PPS), defined
herein as containing the phenylene sulfide structure
--(C.sub.6H.sub.4--S).sub.n-- (wherein n is an integer of 1 or
more) as a component thereof.
[0021] A polyarylene sulfide polymer having one type of arylene
group as a main component can be preferably used. However, in view
of processability and heat resistance, a copolymer containing two
or more types of arylene groups can also be used. A PPS resin
comprising, as a main constituent, a p-phenylene sulfide recurring
unit is particularly preferred since it has excellent
processability and is industrially easily obtained. In addition, a
polyarylene ketone sulfide, polyarylene ketone ketone sulfide,
polyarylene sulfide sulfone, and the like can also be used.
[0022] Specific examples of possible copolymers include a random or
block copolymer having a p-phenylene sulfide recurring unit and an
m-phenylene sulfide recurring unit, a random or block copolymer
having a phenylene sulfide recurring unit and an arylene ketone
sulfide recurring unit, a random or block copolymer having a
phenylene sulfide recurring unit and an arylene ketone ketone
sulfide recurring unit, and a random or block copolymer having a
phenylene sulfide recurring unit and an arylene sulfone sulfide
recurring unit.
[0023] The polyarylene sulfides may optionally include other
components not adversely affecting the desired properties thereof.
Exemplary materials that could be used as additional components
would include, without limitation, antimicrobials, pigments,
antioxidants, surfactants, waxes, flow promoters, particulates, and
other materials added to enhance processability of the polymer.
These and other additives can be used in conventional amounts.
Description
[0024] This invention is directed to a nonwoven web comprising
bicomponent fibers, said fibers comprising continuous phases each
of a first polyarylene sulfide (PAS) component and a polymer
component, in which the first polyarylene sulfide component
contains a tin or a zinc additive or both and the first polyarylene
sulfide component of any given fiber is at least partially exposed
to the outside of that fiber. By "partially exposed" is meant that
at least a portion, of the component appears on an outside surface
of the fiber. The entire outside surface of the fiber may consist
of the first PAS component. The first PAS component may also at
least partially envelop the second polymer component.
[0025] The invention is also directed to an improved process for
manufacturing a nonwoven web comprising the steps of (i) spinning
bicomponent fibers into a nonwoven web, said fibers comprising
continuous phases each of a first polyarylene sulfide component and
a polymer component, in which the first polyarylene sulfide
component contains a tin or a zinc additive or both and the first
polyarylene sulfide component of any given fiber is at least
partially exposed to the outside of that fiber, and (ii)
calendaring the nonwoven web for a time and temperature sufficient
to bond at least a subset of the individual fibers.
[0026] The spinning process of the invention can be any nonwoven
spinning process known to one skilled in the art, for example a
spunbonding or meltblowing process.
[0027] The second polymer component can comprise any thermoplastic
polymeric material. In further embodiments, the second polymer
component can comprise a polymer selected from the group consisting
or polyether ether ketone (PEEK), polyether ketone (PEK),
polyester, polypropylene, polyamide, and mixtures thereof. The
polyester is preferably polyethylene terephthalate (PET),
polytrimethylene terephthalate, or polybutylene terephthalate
(PBT). The second polymer component can further comprise a second
PAS, which may further comprise a calcium salt additive, preferably
calcium stearate. In one embodiment, the first PAS component of the
sheath of the fibers comprises at least one tin(II) salt of an
organic carboxylic acid. The polyarylene sulfide composition may
comprise at least one tin additive comprising a branched tin(II)
carboxylate selected from the group consisting of
Sn(O.sub.2CR).sub.2, Sn(O.sub.2CR)(O.sub.2CR'),
Sn(O.sub.2CR)(O.sub.2CR''), and mixtures thereof, where the
carboxylate moieties O.sub.2CR and O.sub.2CR' independently
represent branched carboxylate anions and the carboxylate moiety
O.sub.2CR'' represents a linear carboxylate anion. In one
embodiment, the branched tin(II) carboxylate comprises
Sn(O.sub.2CR).sub.2, Sn(O.sub.2CR)(O.sub.2CR'), or a mixture
thereof. In one embodiment, the branched tin(II) carboxylate
comprises Sn(O.sub.2CR).sub.2. In one embodiment, the branched
tin(II) carboxylate comprises Sn(O.sub.2CR)(O.sub.2CR'). In one
embodiment, the branched tin(II) carboxylate comprises
Sn(O.sub.2CR)(O.sub.2CR'').
[0028] Optionally, the tin additive may further comprise a linear
tin(II) carboxylate Sn(O.sub.2CR'').sub.2. Generally, the relative
amounts of the branched and linear tin(II) carboxylates are
selected such that the sum of the branched carboxylate moieties
[O.sub.2CR+O.sub.2CR'] is at least about 25% on a molar basis of
the total carboxylate moieties [O.sub.2CR+O.sub.2CR'+O.sub.2CR'']
contained in the additive. For example, the sum of the branched
carboxylate moieties may be at least about 33%, or at least about
40%, or at least about 50%, or at least about 66%, or at least
about 75%, or at least about 90%, of the total carboxylate moieties
contained in the tin additive.
[0029] In one embodiment, the radicals R and R' both comprise from
6 to 30 carbon atoms and both contain at least one secondary or
tertiary carbon. The secondary or tertiary carbon(s) may be located
at any position(s) in the carboxylate moieties O.sub.2CR and
O.sub.2CR', for example in the position a to the carboxylate
carbon, in the position w to the carboxylate carbon, and at any
intermediate position(s). The radicals R and R' may be
unsubstituted or may be optionally substituted with inert groups,
for example with fluoride, chloride, bromide, iodide, nitro,
hydroxyl, and carboxylate groups. Examples of suitable organic R
and R' groups include aliphatic, aromatic, cycloaliphatic,
oxygen-containing heterocyclic, nitrogen-containing heterocyclic,
and sulfur-containing heterocyclic radicals. The heterocyclic
radicals may contain carbon and oxygen, nitrogen, or sulfur in the
ring structure.
[0030] In one embodiment, the radical R'' is a primary alkyl group
comprising from 6 to 30 carbon atoms, optionally substituted with
inert groups, for example with fluoride, chloride, bromide, iodide,
nitro, hydroxyl, and carboxylate groups. In one embodiment, the
radical R'' is a primary alkyl group comprising from 6 to 20 carbon
atoms.
[0031] In one embodiment, the radicals R or R' independently or
both have a structure represented by Formula (I),
##STR00001##
wherein R.sub.1, R.sub.2, and R.sub.3 are independently:
[0032] H;
[0033] a primary, secondary, or tertiary alkyl group having from 6
to 18 carbon atoms, optionally substituted with fluoride, chloride,
bromide, iodide, nitro, hydroxyl, and carboxyl groups;
[0034] an aromatic group having from 6 to 18 carbon atoms,
optionally substituted with alkyl, fluoride, chloride, bromide,
iodide, nitro, hydroxyl, and carboxyl groups; and
[0035] a cycloaliphatic group having from 6 to 18 carbon atoms,
optionally substituted with fluoride, chloride, bromide, iodide,
nitro, hydroxyl, and carboxyl groups;
[0036] with the proviso that when R.sub.2 and R.sub.3 are H,
R.sub.1 is: a secondary or tertiary alkyl group having from 6 to 18
carbon atoms, optionally substituted with fluoride, chloride,
bromide, iodide, nitro, hydroxyl, and carboxyl groups;
[0037] an aromatic group having from 6 to 18 carbons atoms and
substituted with a secondary or tertiary alkyl group having from 6
to 18 carbon atoms, the aromatic group and/or the secondary or
tertiary alkyl group being optionally substituted with fluoride,
chloride, bromide, iodide, nitro, hydroxyl, and carboxyl groups;
and
[0038] a cycloaliphatic group having from 6 to 18 carbon atoms,
optionally substituted with fluoride, chloride, bromide, iodide,
nitro, hydroxyl, and carboxyl groups.
[0039] In one embodiment, the radicals R or R' or both have a
structure represented by Formula (I), and R.sub.3 is H.
[0040] In another embodiment, the radicals R or R' or both have a
structure represented by Formula (II),
##STR00002##
wherein
[0041] R.sub.4 is a primary, secondary, or tertiary alkyl group
having from 4 to 6 carbon atoms, optionally substituted with
fluoride, chloride, bromide, iodide, nitro, and hydroxyl groups;
and
[0042] R.sub.5 is a methyl, ethyl, n-propyl, sec-propyl, n-butyl,
sec-butyl, or tert-butyl group, optionally substituted with
fluoride, chloride, bromide, iodide, nitro, and hydroxyl
groups.
[0043] In one embodiment, the radicals R and R' are the same and
both have a structure represented by Formula (II), where R.sub.4 is
n-butyl and R.sub.5 is ethyl. This embodiment describes the
branched tin(II) carboxylate tin(II) 2-ethylhexanoate, also
referred to herein as tin(II) ethylhexanoate.
[0044] The tin(II) carboxylate(s) may be obtained commercially, or
may be generated in situ from an appropriate source of tin(II)
cations and the carboxylic acid corresponding to the desired
carboxylate(s). The tin(II) additive may be present in the
polyarylene sulfide at a concentration sufficient to provide
improved thermo-oxidative and/or thermal stability. In one
embodiment, the tin(II) additive may be present at a concentration
of about 10 weight percent or less, based on the weight of the
polyarylene sulfide. For example, the tin(II) additive may be
present at a concentration of about 0.01 weight percent to about 5
weight percent, or for example from about 0.25 weight percent to
about 2 weight percent. Typically, the concentration of the tin(II)
additive may be higher in a master batch composition, for example
from about 5 weight percent to about 10 weight percent, or higher.
The tin(II) additive may be added to the molten or solid
polyarylene sulfide as a solid, as a slurry, or as a solution.
[0045] In a further embodiment, the polyarylene sulfide composition
of the sheath of the fibers of the invention further comprises at
least one zinc(II) additive and/or zinc metal [Zn(O)]. The zinc(II)
additive may be an organic additive, for example zinc stearate, or
an inorganic compound such as zinc sulfate or zinc oxide, as long
as the organic or inorganic counter ions do not adversely affect
the desired properties of the polyarylene sulfide composition. The
zinc(II) additive may be obtained commercially, or may be generated
in situ. Zinc metal may be used in the composition as a source of
zinc(II) ions, alone or in conjunction with at least one zinc(II)
additive. In one embodiment the zinc(II) additive is selected from
the group consisting of zinc oxide, zinc stearate, and mixtures
thereof.
[0046] The zinc(II) additive and/or zinc metal may be present in
the polyarylene sulfide at a concentration of about 10 weight
percent or less, based on the weight of the polyarylene sulfide.
For example, the zinc(II) additive and/or zinc metal may be present
at a concentration of about 0.01 weight percent to about 5 weight
percent, or for example from about 0.25 weight percent to about 2
weight percent. Typically, the concentration of the zinc(II)
additive and/or zinc metal may be higher in a master batch
composition, for example from about 5 weight percent to about 10
weight percent, or higher. The at least one zinc(II) additive
and/or zinc metal may be added to the molten or solid polyarylene
sulfide as a solid, as a slurry, or as a solution. The zinc(II)
additive and/or zinc metal may be added together with the tin(II)
salt or separately.
Examples
[0047] Bicomponent spunbond fabric was made from a poly(ethylene
terephthalate) (PET) component and a poly(phenylene sulfide) (PPS)
component. The PET component had an intrinsic viscosity of 0.633
dl/g and is available from PolyQuest, Wilmington, N.C. as PET resin
grade PQB8A-065. The PPS component, available from Ticona
Engineering Polymers, Florence, Ky. under the tradename
Fortron.RTM. PPS was a mixture of 70 wt% grade 0309 C1 and 30 wt %
grade 0317 C1.
[0048] The following materials were used in the examples. All
commercial materials were used as received unless otherwise
indicated. Tin(II) 2-ethylhexanoate (90%) and zinc oxide (99%) were
obtained from Sigma-Aldrich (St. Louis, Mo.). Tin(II) stearate
(98%) (Sn stearate) was obtained from Acros Organics (Morris
Plains, N.J.). Zinc stearate (99%) (Zn stearate) was obtained from
Honeywell Reidel-de Haen (Seelze, Germany). Tin(II)
2-ethylhexanoate is also referred to herein as tin(II)
ethylhexanoate or SnEH.
[0049] Additive, if used, was melt blended with the PPS such that
it comprised the required % of the total mass of the PPS component.
The PET resin was dried in a through air dryer at a temperature of
120.degree. C. to a moisture content of less than 50 parts per
million. The PPS resins were dried in a through air dryer at a
temperature of 115.degree. C. to a moisture content of less than
150 parts per million. The PET polymers were heated in an extruder
at 290.degree. C. and the PPS resins heated in a separate extruder
at 295.degree. C. The two polymers were metered to a spin-pack
assembly where the two melt streams were separately filtered and
then combined through a stack of distribution plates to provide
multiple rows of spunbond fibers having sheath-core cross sections.
Such processing is well known to those skilled in the art. The PET
component comprised the core and the PPS component comprised the
sheath.
[0050] A spin pack assembly consisting of 2158 round capillary
openings was heated to 295.degree. C. and the PPS and PET polymers
spun through each capillary at a polymer throughput rate of 2.2
g/hole/min. The PET component consisted of 70% by weight of the
total weight of the spun bond fibers. The fibers were cooled in a
cross flow quench extending over a length of 122 cm. An attenuating
force was provided to the bundle of fibers by a rectangular slot
jet. The distance between the spin-pack to the entrance of the jet
was 147 cm. The fibers exiting the jet were collected on a forming
belt traveling at 87.4 m/min. A vacuum was applied underneath the
belt to help pin the fibers to the belt. The spunbond layer was
then smooth-calendered by passing the web between two smooth metal
to achieve filament to filament bonding. The bonding conditions
were 135.degree. C. roll temperature and 875 N/cm nip pressure.
After thermal bonding, the spunbond sheet was formed into a roll
using a winder.
[0051] In an additional step, the non-woven web was then
smooth-calendered to achieve further densification of the already
bonded non-woven web. The web was passed between 2 heated stainless
steel rolls having a diameter of 76.2 cm at a nip pressure of 4200
N/cm. The line speed was 61 m/min and the rolls were heated to a
surface temperature of 200.degree. C. After calendaring, the
spunbond sheet had a basis weight of 51 g/m.sup.2.
[0052] The results of tensile testing on these samples are given in
the table below, where SnEH is tin (II) ethylhexanoate, ZnO is zinc
oxide, SnO is tin oxide, Zn Stearate is zinc stearate, and Sn
Stearate is tin stearate. Tensile strength and work to break of the
nonwoven sheets were measured on an Instron-type testing machine
using test specimens 2.54 cm wide and a gage length of 18 cm, in
accordance with ASTM D 828-97. Only the machine direction (MD)
results are reported.
Results
TABLE-US-00001 [0053] Additive and Level in MD Tensile MD Work to
Example PPS layer. Strength (kg/cm) Break (kg cm) A None 3.79 20.02
(Comparative) 1 1% Zn Stearate 3.80 19.86 2 0.5% SnEH 6.01 34.65 3
0.5%/0.13% Zn 4.21 23.22 Stearate/ZnO 4 0.25% ZnO 4.30 24.29 5
0.25% SnO 5.06 28.45 6 0.66%/0.33% Zn 5.36 29.81 Stearate/SnEH 7
0.5%/0.25% Zn 4.26 19.53 Stearate/SnEH 8 1% Ca Stearate 3.93 18.88
9 0.5% Ca Stearate 3.53 18.70
[0054] The effect of the tin and/or zinc additives in raising the
tensile strength and total energy to break of the web is clear from
these examples.
* * * * *