U.S. patent application number 11/648953 was filed with the patent office on 2008-07-03 for nonwovens fabrics produced from multicomponent fibers comprising sulfopolyesters.
Invention is credited to Scott Ellery George, Rakesh Kumar Gupta, Daniel William Klosiewicz.
Application Number | 20080160859 11/648953 |
Document ID | / |
Family ID | 39584665 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080160859 |
Kind Code |
A1 |
Gupta; Rakesh Kumar ; et
al. |
July 3, 2008 |
Nonwovens fabrics produced from multicomponent fibers comprising
sulfopolyesters
Abstract
A process for making a nonwoven fabric is provided comprising:
(A) collecting multicomponent fibers to form a non-woven web;
wherein the multicomponent fiber comprises at least one water
dispersible sulfopolyester and at least one water non-dispersible
polymer; wherein said multicomponent fiber has a plurality of
domains comprising the water non-dispersible polymer; wherein the
domains are substantially isolated from each other by the water
dispersible sulfopolyester intervening between the domains; (B)
contacting the non-woven web with water at a sufficient temperature
and pressure to remove a portion of the water dispersible
sulfopolyester thereby forming a microfiber web; and (C)
hydroentangling the microfiber web to produce the nonwoven fabric.
A process is also provided wherein steps (B) and (C) are combined.
Fibrous articles utilizing the nonwoven fabrics are also
provided.
Inventors: |
Gupta; Rakesh Kumar;
(Kingsport, TN) ; Klosiewicz; Daniel William;
(Kingsport, TN) ; George; Scott Ellery;
(Kingsport, TN) |
Correspondence
Address: |
POLLY C. OWEN
P.O. BOX 511
KINGSPORT
TN
37662-5075
US
|
Family ID: |
39584665 |
Appl. No.: |
11/648953 |
Filed: |
January 3, 2007 |
Current U.S.
Class: |
442/364 ;
264/172.11 |
Current CPC
Class: |
D01F 8/14 20130101; D04H
1/4358 20130101; D04H 1/4382 20130101; D04H 1/4291 20130101; D04H
1/435 20130101; D04H 1/49 20130101; Y10T 442/641 20150401; D04H
1/4334 20130101 |
Class at
Publication: |
442/364 ;
264/172.11 |
International
Class: |
D04H 1/00 20060101
D04H001/00; D01D 5/30 20060101 D01D005/30 |
Claims
1. A process for making a nonwoven fabric comprising: (A)
collecting multicomponent fibers to form a non-woven web; wherein
said multicomponent fiber comprises at least one water dispersible
sulfopolyester and at least one water non-dispersible polymer;
wherein said multicomponent fiber has a plurality of domains
comprising said water non-dispersible polymer; wherein said domains
are substantially isolated from each other by said water
dispersible sulfopolyester intervening between said domains; (B)
contacting said non-woven web with water at a sufficient
temperature and pressure to remove a portion of said water
dispersible sulfopolyester thereby forming a microfiber web; and
(C) hydroentangling said microfiber web to produce said nonwoven
fabric.
2. A process according to claim 1 wherein said sulfopolyester
comprises dicarboxylic acid monomer residues, sulfomonomer
residues, diol monomer residues, and repeating units.
3. A process according to claim 2 wherein said dicarboxylic acids
are selected from aliphatic diacids, cycloaliphatic dicarboxylic
acids, aromatic dicarboxylic acids, and combinations thereof.
4. A process according to claim 3 wherein said dicarboxylic acids
are selected from succinic, glutaric, adipic, azelaic, sebacic,
fumaric, maleic, itaconic, 1,3-cyclohexane dicarboxylic,
1,4-cyclohexanedicarboxylic, diglycolic,
2,5-norbornanedicarboxylic, phthalic, terephthalic,
1,4-naphthalenedicarboxylic, 2,5-naphthalenedicarboxylic,
2,6-naphthalenedicarboxylic, 2,7-naphthalenedicarboxylic, diphenic,
4,4'-oxydibenzoic, 4,4'-sulfonyldibenzoic, isophthalic, and
combinations thereof.
5. A process according to claim 2 wherein said sulfomonomer is a
metal sulfonate salt of a sulfophthalic acid, sulfoterephthalic
acid, sulfoisophthalic acid, or combinations thereof.
6. A process according to claim 2 wherein said diol residues are
selected from the group consisting of ethylene glycol, diethylene
glycol, triethylene glycol, poly(ethylene) glycols,
1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol,
thiodiethanol, 1,2-cyclohexanedimethanol,
1,3-cyclohexanedimethanol, 1,4-cyclohexane-dimethanol,
2,2,4,4-tetramethyl-1,3-cyclobutanediol, p-xylylenediol, and
combinations thereof.
7. A process according to claim 2 wherein said sulfopolyester
further comprises at least one branching monomer.
8. A process according to claim 7 wherein said branching monomer is
at least one selected from the group consisting of
1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin,
pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol,
trimellitic anhydride, pyromellitic dianhydride, dimethylol
propionic acid, or combinations thereof.
9. A process according to claim 1 wherein said water-nondispersible
polymers are selected from polyolefins, polyesters, polyamides,
polylactides, polycaprolactone, polycarbonate, polyurethane,
polyvinyl chloride, and combinations thereof.
10. A process according to claim 1 wherein the shaped cross section
of said multicomponent fiber is an islands-in-the-sea, segmented
pie, or sheath-core configuration.
11. A process according to claim 1 wherein said sulfopolyester has
a glass transition temperature (Tg) of at least 57.degree. C. and
said water dispersible sulfopolyester comprises: (i) residues of
one or more dicarboxylic acids; (ii) about 4 to about 40 mole %,
based on the total repeating units, of residues of at least one
sulfomonomer having 2 functional groups and one or more sulfonate
groups attached to an aromatic or cycloaliphatic ring wherein said
functional groups are hydroxyl, carboxyl, or a combination thereof;
(iii) one or more diol residues wherein at least 25 mole %, based
on the total diol residues, is a poly(ethylene glycol) having a
structure H--(OCH.sub.2--CH.sub.2).sub.n--OH wherein n is an
integer in the range of 2 to about 500; and (iv) 0 to about 25 mole
%, based on the total repeating units, of residues of a branching
monomer having 3 or more functional groups wherein said functional
groups are hydroxyl, carboxyl, or a combination thereof; wherein
said fiber has a plurality of segments comprising said
water-nondispersable polymers and said segments are substantially
isolated from each other by said sulfopolyester intervening between
said segments.
12. A process according to claim 1 wherein said sulfopolyester has
a melt viscosity of less than 12,000 poise measured at 240.degree.
C. and 1 rad/sec shear rate.
13. A process according to claim 12 wherein said sulfopolyester has
a melt viscosity less than 6,000 poise measured at 240.degree. C.
and 1 rad/sec shear rate.
14. A process according to claim 13 wherein said sulfopolyester has
a melt viscosity less than 4,000 poise measured at 240.degree. C.
and 1 rad/sec shear rate.
15. A process according to claim 1 wherein said collecting is
accomplished by at least one method selected from the group
consisting of mechanical needling, chemical binding, thermally
calendaring, ultrasonic fusing, and hydroentangling.
16. A process according to claim 15 wherein said collecting is
accomplished by hydroentangling and the hydroentangling energy in
said hydrotangling step involves about 20% to about 50% of the
amount of hydroentangling energy expended in Step (C).
17. A process according to claim 1 wherein said multicomponent
fibers are produced by a spunbond process or meltblown process.
18. A process according to claim 1 wherein the weight of said
nonwoven web ranges from about 10 grams/m.sup.2 to about 800
grams/m.sup.2.
19. A process according to claim 18 wherein the weight of said
nonwoven web ranges from about 10 grams/m.sup.2 to about 400
grams/m.sup.2.
20. A process according to claim 19 wherein the weight of said
nonwoven web ranges from about 50 grams/m.sup.2 to about 150
grams/m.sup.2.
21. A process according to claim 1 wherein the extraction
temperature of said water dispersible sulfopolyester ranges from
about 20.degree. C. to about 100.degree. C.
22. A process according to claim 1 wherein the pressure of the
water during Step (B) ranges from about 30 bar to about 600
bar.
23. A process according to claim 22 wherein the pressure of the
water during Step (B) ranges from about 50 barr to about 300
barr.
24. A process according to claim 1 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove about 30% by weight to about 100% by weight of the total
water dispersible sulfopolyester contained in said nonwoven
web.
25. A process according to claim 24 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove greater than 90% by weight of the total water dispersible
sulfopolyester from said nonwoven web.
26. A process according to claim 25 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove greater than 95% by weight of the total water dispersible
sulfopolyester from said nonwoven web.
27. A process according to claim 1 wherein said nonwoven web is
contacted with water for a time period of from about 10 to about
600 seconds whereby said water dispersible sulfopolyester is
dissipated or dissolved.
28. A process according to claim 1 wherein the microfibers in the
microfiber web have an average fineness of less than 30% of the
denier of said multicomponent fiber.
29. A process according to claim 28 wherein said microfibers in
said microfiber web have an average fineness of 1 dpf or less.
30. A process according to claim 29 wherein said microfibers in
said microfiber web have an average fineness of 0.5 dpf or
less.
31. A process according to claim 1 wherein said nonwoven web is
contacted with water in Step (B) using water jets.
32. A process according to claim 31 wherein one to eight water jet
heads are utilized.
33. A process according to claim 31 wherein the amount of water
used in Step (B) ranges from about 500 times to about 1000 times
the weight of said nonwoven web.
34. A process according to claim 1 wherein the wash water from Step
(B) and Step (C) can be reclaimed.
35. A process according to claim 34 wherein 80% or more of the wash
water is reclaimed.
36. A process according to claim 1 wherein the temperature of the
water in Step (C) is less than 40.degree. C.
37. A process according to claim 1 wherein the pressure of the
water in Step (C) ranges from about 150 bar to about 250 bar.
38. A process according to claim 1 wherein less than 1% by weight
of the water dispersible sulfopolyester in Step (C) is removed from
said microfiber web.
39. A process according to claim 38 wherein in Step (C) less than
0.5% by weight of the water dispersible sulfopolyester is removed
from the microfiber web.
40. A process according to claim 38 wherein in Step (C) less than
0.1% by weight of the water dispersible sulfopolyester is removed
from the microfiber web.
41. A process according to claim 1 wherein said hydroentangling in
Step (C) is conducted by water jet heads.
42. A process according to claim 41 wherein number of water jet
heads range from 1 to about 20.
43. A process for making a nonwoven fabric comprising: (A)
collecting multicomponent fibers to form a non-woven web; wherein
said multicomponent fiber comprises at least one water dispersible
sulfopolyester and at least one water non-dispersible polymer;
wherein said multicomponent fiber has a plurality of domains
comprising said water non-dispersible polymer; wherein said domains
are substantially isolated from each other by said water
dispersible sulfopolyester intervening between said domains; and
(B) contacting said non-woven web with water at a sufficient
temperature and pressure to remove a portion of said sulfopolyester
thereby forming a microfibers and simultaneously hydroentangling
said microfibers to produce said nonwoven fabric.
44. A process according to claim 43 wherein said sulfopolyester
comprises dicarboxylic acid monomer residues, sulfomonomer
residues, diol monomer residues, and repeating units.
45. A process according to claim 44 wherein said dicarboxylic acids
are selected from aliphatic diacids, cycloaliphatic dicarboxylic
acids, aromatic dicarboxylic acids, and combinations thereof.
46. A process according to claim 45 wherein said dicarboxylic acids
are selected from succinic, glutaric, adipic, azelaic, sebacic,
fumaric, maleic, itaconic, 1,3-cyclohexane dicarboxylic,
1,4-cyclohexanedicarboxylic, diglycolic,
2,5-norbornanedicarboxylic, phthalic, terephthalic,
1,4-naphthalenedicarboxylic, 2,5-naphthalenedicarboxylic,
2,6-naphthalenedicarboxylic, 2,7-naphthalenedicarboxylic, diphenic,
4,4'-oxydibenzoic, 4,4'-sulfonyldibenzoic, isophthalic, and
combinations thereof.
47. A process according to claim 44 wherein said sulfomonomer is a
metal sulfonate salt of a sulfophthalic acid, sulfoterephthalic
acid, sulfoisophthalic acid, or combinations thereof.
48. A process according to claim 44 wherein said diol residues are
selected from the group consisting of ethylene glycol, diethylene
glycol, triethylene glycol, poly(ethylene) glycols,
1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol,
2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol,
2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol,
thiodiethanol, 1,2-cyclohexanedimethanol,
1,3-cyclohexanedimethanol, 1,4-cyclohexane-dimethanol,
2,2,4,4-tetramethyl-1,3-cyclobutanediol, p-xylylenediol, and
combinations thereof.
49. A process according to claim 44 wherein said sulfopolyester
further comprises at least one branching monomer.
50. A process according to claim 49 wherein said branching monomer
is at least one selected from the group consisting of
1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin,
pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol,
trimellitic anhydride, pyromellitic dianhydride, dimethylol
propionic acid, or combinations thereof.
51. A process according to claim 43 wherein said
water-nondispersible polymers are selected from polyolefins,
polyesters, polyamides, polylactides, polycaprolactone,
polycarbonate, polyurethane, polyvinyl chloride, and combinations
thereof.
52. A process according to claim 43 wherein the shaped cross
section of said multicomponent fiber is an islands-in-the-sea,
segmented pie, or sheath-core configuration.
53. A process according to claim 43 wherein said sulfopolyester has
a glass transition temperature (Tg) of at least 57.degree. C. and
said water dispersible sulfopolyester comprises: (i) residues of
one or more dicarboxylic acids; (ii) about 4 to about 40 mole %,
based on the total repeating units, of residues of at least one
sulfomonomer having 2 functional groups and one or more sulfonate
groups attached to an aromatic or cycloaliphatic ring wherein said
functional groups are hydroxyl, carboxyl, or a combination thereof;
(iii) one or more diol residues wherein at least 25 mole %, based
on the total diol residues, is a poly(ethylene glycol) having a
structure H--(OCH.sub.2--CH.sub.2).sub.n--OH wherein n is an
integer in the range of 2 to about 500; and (iv) 0 to about 25 mole
%, based on the total repeating units, of residues of a branching
monomer having 3 or more functional groups wherein said functional
groups are hydroxyl, carboxyl, or a combination thereof; wherein
said fiber has a plurality of segments comprising said
water-nondispersable polymers and said segments are substantially
isolated from each other by said sulfopolyester intervening between
said segments.
54. A process according to claim 43 wherein said sulfopolyester has
a melt viscosity of less than 12,000 poise measured at 240.degree.
C. and 1 rad/sec shear rate.
55. A process according to claim 54 wherein said sulfopolyester has
a melt viscosity less than 6,000 poise measured at 240.degree. C.
and 1 rad/sec shear rate.
56. A process according to claim 56 wherein said sulfopolyester has
a melt viscosity less than 4,000 poise measured at 240.degree. C.
and 1 rad/sec shear rate.
57. A process according to claim 43 wherein said collecting is
accomplished by at least one method selected from the group
consisting of mechanical needling, chemical binding, thermally
calendaring, ultrasonic fusing, and hydroentangling.
58. A process according to claim 57 wherein said collecting is
accomplished by hydroentangling and the hydroentangling energy in
said hydrotangling step involves about 20% to about 50% of the
amount of hydroentangling energy expended in Step (C).
59. A process according to claim 43 wherein said multicomponent
fibers are produced by a spunbond process or meltblown process.
60. A process according to claim 43 wherein the weight of said
nonwoven web ranges from about 10 grams/m.sup.2 to about 800
grams/m.sup.2.
61. A process according to claim 60 wherein the weight of said
nonwoven web ranges from about 10 grams/m.sup.2 to about 400
grams/m.sup.2.
62. A process according to claim 61 wherein the weight of said
nonwoven web ranges from about 50 grams/m.sup.2 to about 150
grams/m.sup.2.
63. A process according to claim 43 wherein the extraction
temperature of said water dispersible sulfopolyester ranges from
about 20.degree. C. to about 100.degree. C.
64. A process according to claim 43 wherein the pressure of the
water during Step (B) ranges from about 30 bar to about 600
bar.
65. A process according to claim 64 wherein the pressure of the
water during Step (B) ranges from about 50 barr to about 300
barr.
66. A process according to claim 43 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove about 30% by weight to about 100% by weight of the total
water dispersible sulfopolyester contained in said nonwoven
web.
67. A process according to claim 66 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove greater than 90% by weight of the total water dispersible
sulfopolyester from said nonwoven web.
68. A process according to claim 67 wherein said nonwoven web is
contacted with the water in Step (B) for a time sufficient to
remove greater than 95% by weight of the total water dispersible
sulfopolyester from said nonwoven web.
69. A process according to claim 43 wherein said nonwoven web is
contacted with water for a time period of from about 10 to about
600 seconds whereby said water dispersible sulfopolyester is
dissipated or dissolved.
70. A process according to claim 43 wherein the microfibers in the
microfiber web have an average fineness of less than 30% of the
denier of said multicomponent fiber.
71. A process according to claim 70 wherein said microfibers in
said microfiber web have an average fineness of 1 dpf or less.
72. A process according to claim 71 wherein said microfibers in
said microfiber web have an average fineness of 0.5 dpf or
less.
73. A process according to claim 43 wherein said nonwoven web is
contacted with water in Step (B) using water jets.
74. A process according to claim 73 wherein one to eight water jet
heads are utilized.
75. A process according to claim 73 wherein the amount of water
used in Step (B) ranges from about 500 times to about 1000 times
the weight of said nonwoven web.
76. A process according to claim 43 wherein the wash water from
Step (B) and Step (C) can be reclaimed.
77. A process according to claim 76 wherein 80% or more of the wash
water is reclaimed.
78. A process according to claim 43 wherein the temperature of the
water in Step (C) is less than 40.degree. C.
79. A process according to claim 43 wherein the pressure of the
water in Step (C) ranges from about 150 bar to about 250 bar.
80. A process according to claim 43 wherein less than 1% by weight
of the water dispersible sulfopolyester in Step (C) is removed from
said microfiber web.
81. A process according to claim 80 wherein in Step (C) less than
0.5% by weight of the water dispersible sulfopolyester is removed
from the microfiber web.
82. A process according to claim 81 wherein in Step (C) less than
0.1% by weight of the water dispersible sulfopolyester is removed
from the microfiber web.
83. A process according to claim 43 wherein said hydroentangling in
Step (C) is conducted by water jet heads.
84. A process according to claim 83 wherein number of water jet
heads range from 1 to about 20.
85. A process according to claim 1 or 43 wherein said nonwoven
fabric is heat set.
86. A nonwoven fabric produced by the process of claim 1 or claim
43 wherein said nonwoven fabric is utilized in at least one of the
following end uses: clothing, curtains, upholstery, uniforms,
personal care products, hospital/surgical and other medical
disposables, multilayer nonwovens, laminates and composites,
protective fabrics and layers, geotextiles, industrial wipes, and
filter media.
Description
FIELD OF THE INVENTION
[0001] The present invention pertains to processes to produce
nonwoven fabrics from multicomponent fibers wherein the
multicomponent fibers comprise at least one water-dispersible
sulfopolyester and at least one water non-dispersible polymer.
BACKGROUND OF THE INVENTION
[0002] Traditional textile fabrics are made by weaving or knitting.
Nonwoven fabrics are similar to woven and knitted fabrics in that
both are planar, inherently flexible, porous structures composed of
polymer-based materials. The main difference between the two is the
process in which the fabric is made. Woven fabrics are made by
interlacing two or more sets of yarns at right angles to one
another in a designated order. Nonwoven fabrics are made by placing
a predetermined number of fibers or filaments into a
two-dimensional array and locking them together. The nonwoven
fabric can be assembled by mechanically, chemically, or thermally
interlocking layers or networks of fibers, filaments or yarns.
Typically, processes for producing nonwoven fabrics can be grouped
into four general classifications: textile, paper, extrusion, and
hybrid, meaning a combination of these technologies are utilized.
These fabrics are technically sophisticated engineered structures
that can be made to resemble woven fabrics and can exceed the
properties of woven fabrics.
[0003] Extrusion technology is used to produce spunbond, meltblown,
and porous-film nonwovens. These types of nonwovens are sometimes
called polymer-laid nonwovens. Spunbond and meltblown processes are
an advancement in the production of nonwovens fabrics since the
nonwovens are made directly from the materials used to make the
fibers themselves, thus eliminating the fiber production step. The
spunbond process transforms polymer directly to fabric by extruding
filaments, orienting them as bundles or groupings, layering them on
a conveying screen, and interlocking them by thermal fusion,
mechanical entanglement, chemical adhesives, or combinations of
these methods. In the meltblown process, the polymer is heated to
the liquid state and as it passes through an extrusion orifice, it
is injected with sonic velocity air at about 250 to 500.degree. C.
The fast moving air stream stretches the molten polymer and
solidifies it to produce fine fibers. The fibers are then separated
from the air stream as an entangled web and compressed between
heated rolls.
[0004] Nonwovens are utilized in textile applications such as, for
example, clothing, curtains, upholstery, and uniforms. Nonwoven
fabrics can also be utilized in personal care products, such as,
but not limited to, wipes, feminine hygiene products, baby diapers,
adult incontinence briefs, and hospital/surgical and other medical
disposable. Other applications include, but are not limited to,
protective fabrics and layers, geotextiles, industrial wipes, and
filter media.
[0005] Accordingly, there is a need for new processes for producing
nonwoven fabrics and fibrous articles prepared therefrom that are
more efficient and/or less costly. This invention provides novel
processes to produce nonwoven fabrics from multicomponent fibers
comprising at least one water dispersible sulfopolyester and at
least one water non-dispersible polymers.
SUMMARY OF THE INVENTION
[0006] In one embodiment of the invention, a process for making a
nonwoven fabric is provided. The process comprises: (A) collecting
multicomponent fibers to form a non-woven web; wherein the
multicomponent fiber comprises at least one water dispersible
sulfopolyester and at least one water non-dispersible polymer;
wherein the multicomponent fiber has a plurality of domains
comprising the water non-dispersible polymer; wherein the domains
are substantially isolated from each other by the water dispersible
sulfopolyester intervening between the domains; (B) contacting the
non-woven web with water at a sufficient temperature and pressure
to remove a portion of the water dispersible sulfopolyester thereby
forming a microfiber web; and (C) hydroentangling the microfiber
web to produce the nonwoven fabric.
[0007] In another embodiment of the present invention, another
process for making a nonwoven fabric is provided. The process
comprises: (A) collecting the multicomponent fibers to form a
non-woven web; wherein the multicomponent fiber comprises at least
one water dispersible sulfopolyester and at least one water
non-dispersible polymer; wherein the multicomponent fiber has a
plurality of domains comprising the water non-dispersible polymer;
wherein the domains are substantially isolated from each other by
the water dispersible sulfopolyester intervening between the
domains; and (B) contacting the non-woven web with water at a
sufficient temperature and pressure to remove a portion of the
water dispersible sulfopolyester thereby forming microfibers and
simultaneously hydroentangling the microfibers to produce the
nonwoven fabric.
[0008] Our invention thus offers a novel and inexpensive process to
produce nonwoven fabric. The nonwoven fabric may be in the form of
a flat fabric or a 3-dimensional shape and may be incorporated into
a variety of fibrous articles such as those discuss previously.
BRIEF DESCRIPTION OF FIGURES
[0009] FIG. 1 illustrates the sponbond process.
[0010] FIG. 2 illustrates how the examples relate to one
another.
DETAILED DESCRIPTION
[0011] The present invention may be understood more readily by
reference to the following detailed description of preferred
embodiments of the invention and the Examples included therein and
to the Figures and their previous and following description.
[0012] Before the present compounds, compositions, articles,
devices, and/or methods are disclosed and described, it is to be
understood that this invention is not limited to specific synthetic
methods, specific processes, or to particular apparatuses, as such
may, of course, vary. It is also to be understood that the
terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting.
[0013] In this specification and in the claims, which follow,
reference will be made to a number of terms which shall be defined
to have the following meanings.
[0014] As used in the specification and the appended claims, the
singular forms "a," "an" and "the" include plural referents unless
the context clearly dictates otherwise. Thus, for example,
reference to a polymer includes one or more polymers.
[0015] Ranges may be expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, another embodiment includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," it will be understood that the particular value
forms another embodiment. It will be further understood that the
endpoints of each of the ranges are significant both in relation to
the other endpoint, and independently of the other endpoint.
Further, the ranges stated in this disclosure and the claims are
intended to include the entire range specifically and not just the
endpoint(s). For example, a range stated to be 0 to 10 is intended
to disclose all whole numbers between 0 and 10 such as, for example
1, 2, 3, 4, etc., all fractional numbers between 0 and 10, for
example 1.5, 2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10.
Also, a range associated with chemical substituent groups such as,
for example, "C1 to C5 hydrocarbons", is intended to specifically
include and disclose C1 and C5 hydrocarbons as well as C2, C3, and
C4 hydrocarbons.
[0016] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where said event or circumstance
occurs and instances where it does not. For example, the phrase
"optionally heated" means that the material may or may not be
heated and that such phrase includes both heated and unheated
processes.
[0017] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, each numerical parameter should at
least be construed in light of the number of reported significant
digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting
forth the broad scope of the invention are approximations, the
numerical values set forth in the specific examples are reported as
precisely as possible. Any numerical value, however, inherently
contain certain errors necessarily resulting from the standard
deviation found in their respective testing measurements.
[0018] As used herein, the term "nonwoven fabric" or "nonwoven web"
means a structure of individual fibers or threads which are
interlaid, but not in an identifiable manner as in a knitted
fabric. The basis weight of nonwoven fabrics is usually expressed
in ounces of material per square yard (osy) or grams per square
meter (gsm).
[0019] The term "fiber" as used herein refers to an elongated
extrudate formed by passing a polymer through a forming orifice
such as a die. Unless noted as otherwise the term "fibers" include
discontinuous strands having a definite length and continuous
strands of material, such as filaments. The nonwoven fabric of the
present invention may be formed from staple multicomponent fibers.
Such staple fibers may be carded and bonded to form the nonwoven
fabric. Desirably, however, the nonwoven fabric of the present
invention is
[0020] made with continuous multicomponent filaments which are
extruded, drawn, and laid on a traveling forming surface.
[0021] As used herein, the term "microfibers" means small diameter
fibers having an average diameter not greater than about 12
microns, for example, having an average diameter of from about 3
microns to about 8 microns. Fibers are also commonly discussed in
terms of denier. A lower denier indicates a finer fiber and a
higher denier indicates a thicker or heavier fiber. For example, a
15 micron polypropylene fiber has a denier of about 1.42
(15.sub.2.times.0.89.times.0.00707=1.415). The microfibers utilized
to produce the nonwoven fabric of this invention typically have d/f
values of 1 or less, 0.5 or less, or 0.1 or less.
[0022] As used herein the term "multicomponent fibers" or
"conjugate fibers" refers to fibers which have been formed from at
least two polymer components. Such fibers are usually extruded from
separate extruders but spun together to form one fiber. The
polymers of the respective components are usually different from
each other although multicomponent fibers may comprise separate
components of similar or identical polymeric materials. The
individual components are typically arranged in substantially
constantly positioned distinct segments or zones across the
cross-section of the multicomponent fiber and extend substantially
along the entire length of the multicomponent fiber. The
configuration of such multicomponent fibers may be, for example, a
side by side arrangement, a pie arrangement or other arrangement.
Multicomponent fibers and methods of making the same are taught in
U.S. Pat. No. 5,108,820 to Kaneko et al.; U.S. Pat. No. 4,795,668
to Krueger et al.; U.S. Pat. No. 5,382,400 to Pike et al.; U.S.
Pat. No. 5,336,552 to Strack et al.; U.S. patent application Ser.
No. 08/550,042 filed Oct. 30, 1996 to Cook; and U.S. patent
application Ser. No. 11/344,320 filed Jan. 31, 2006 to Gupta et al.
The fibers and individual components comprising the same may also
have various irregular shapes such as those described in U.S. Pat.
No. 5,277,976 to Hogle et al.; U.S. Pat. Nos. 5,162,074 and
5,466,410 to Hills; and U.S. Pat. Nos. 5,069,970 and 5,057,368 to
Largman et al. The entire contents of the aforesaid patents and
applications are incorporated herein by reference to the extent
they do not contradict the statements herein.
[0023] As used herein, the term "polymer" generally includes, but
is not limited to, homopolymers, copolymers, such as for example,
block, graft, random and alternating copolymers, terpolymers, etc.,
and blends and modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
geometric configurations of the molecules. These configurations
include, but are not limited to, isotactic, syndiotactic and random
symmetries.
[0024] The term "water-dispersible", as used herein in reference to
the water dispersible sulfopolyester as one component of a
multicomponent fiber, is intended to be synonymous with the terms
"water-dissipatable", "water-disintegratable", "water-dissolvable",
"water-dispellable", "water soluble", "water-removable",
"hydrosoluble", and "hydrodispersible" and is intended to mean that
the sulfopolyester component is sufficiently removed from the
multicomponent fiber and is dispersed or dissolved by the action of
water to enable the release and separation of the water
non-dispersible polymer fibers contained therein. The terms
"dispersed", "dispersible", "dissipate", or "dissipatable" mean
that, using a sufficient amount of deionized water (e.g., 100:1
water:fiber by weight) to form a loose suspension or slurry of the
fibers, at a temperature of about 60.degree. C., and within a time
period of up to 5 days, the sulfopolyester component dissolves,
disintegrates, or separates from the multicomponent fiber, leaving
behind a plurality of microfibers from the water non-dispersible
polymer segments. In the context of this invention, all of these
terms refer to the activity of water or a mixture of water and a
water-miscible cosolvent on the water dispersible sulfopolyesters
described herein. Examples of such water-miscible cosolvents
include, but are not limited to, alcohols, ketones, glycol ethers,
esters and the like. It is intended for this terminology to include
conditions where the water dispersible sulfopolyester is dissolved
to form a true solution as well as those where the water
dispersible sulfopolyester is dispersed within the aqueous medium.
Often, due to the statistical nature of sulfopolyester
compositions, it is possible to have a soluble fraction and a
dispersed fraction when a single sulfopolyester sample is placed in
an aqueous medium.
[0025] The term "segment" or "domain" or "zone" when used to
describe the shaped cross section of a multicomponent fiber refers
to the area within the cross section comprising the water
non-dispersible polymers where these domains or segments are
substantially isolated from each other by the water-dispersible
sulfopolyester intervening between the segments or domains. The
term "substantially isolated", as used herein, is intended to mean
that the segments or domains are set apart from each other to
permit the segments domains to form individual fibers upon removal
of the sulfopolyester. Segments or domains or zones can be of
similar size and shape or varying size and shape. Again, segments
or domains or zones can be arranged in any configuration. These
segments or domains or zones are "substantially continuous" along
the length of the multicomponent extrudate or fiber. The term
"substantially continuous" means continuous along at least a 10 cm
length of the multicomponent fiber.
[0026] The present invention provides processes to produce nonwoven
fabrics from multicomponent fibers wherein the multicomponent
fibers comprise at least one water-dispersible sulfopolyester and
at least one water non-dispersible polymer.
[0027] In one embodiment, a process is provided comprising: (A)
collecting multicomponent fibers to form a non-woven web; wherein
the multicomponent fiber comprises at least one water dispersible
sulfopolyester and at least one water non-dispersible polymer;
wherein the multicomponent fiber has a plurality of domains
comprising the water non-dispersible polymer; wherein the domains
are substantially isolated from each other by the water dispersible
sulfopolyester intervening between the domains; (B) contacting the
non-woven web with water at a sufficient temperature and pressure
to remove a portion of the water dispersible sulfopolyester thereby
forming a microfiber web; and (C) hydroentangling the microfiber
web to produce the nonwoven fabric.
[0028] The multicomponent fibers of our invention can be prepared
by melt spinning a single sulfopolyester or sulfopolyester blend
with the water non-dispersible polymer immiscible with the
sulfopolyester. For example, in U.S. Pat. No. 5,916,678, a
multicomponent fiber is prepared by extruding the sulfopolyester
and one or more water non-dispersible polymers, which are
immiscible with the sulfopolyester, separately through a spinneret
having a shaped or engineered transverse geometry such as, for
example, an "islands-in-the-sea", sheath-core, side-by-side, or
segmented pie configuration. The water dispersible sulfopolyester
is later removed by dissolving the interfacial layers or pie
segments and leaving the smaller filaments or microfibers of the
water non-dispersible polymer(s). These fibers of the water
non-dispersible polymer have fiber size much smaller than the
multicomponent fiber before removing the water dispersible
sulfopolyester.
[0029] In one embodiment, the multicomponent fiber is produced by
feeding the sulfopolyester and water non-dispersible polymers to a
polymer distribution system where the polymers are introduced into
a segmented spinneret plate. The polymers follow separate paths to
the fiber spinneret and are combined at the spinneret hole which
comprises either two concentric circular holes thus providing a
sheath-core type fiber, or a circular spinneret hole divided along
a diameter into multiple parts to provide a fiber having a
side-by-side type. Alternatively, the immiscible water dispersible
sulfopolyester and water non-dispersible polymers may be introduced
separately into a spinneret having a plurality of radial channels
to produce a multicomponent fiber having a segmented pie cross
section. Typically, the sulfopolyester will form the "sheath"
component of a sheath core configuration. In fiber cross sections
having a plurality of segments, the water non-dispersible segments,
typically, are substantially isolated from each other by the
sulfopolyester. Alternatively, multicomponent fibers may be formed
by melting the sulfopolyester and water non-dispersible polymers in
separate extruders and directing the polymer flows into one
spinneret with a plurality of distribution flow paths in form of
small thin tubes or segments to provide a multicomponent fiber
having an islands-in-the-sea shaped cross section. An example of
such a spinneret is described in U.S. Pat. No. 5,366,804, herein
incorporated by reference to the extent it does not contradict the
statements herein. In the present invention, typically, the
sulfopolyester will form the "sea" component and the water
non-dispersible polymer will form the "islands" component.
[0030] As stated within this disclosure, the shaped cross section
of a multicomponent fiber can, for example, be in the form of a
sheath core, islands-in-the sea, segmented pie, hollow segmented
pie; off-centered segmented pie, etc.
[0031] The multicomponent fiber of the present invention is
prepared from polyesters or, more specifically sulfopolyesters,
comprising dicarboxylic acid monomer residues, sulfomonomer
residues, diol monomer residues, and repeating units. The
sulfomonomer may be a dicarboxylic acid, a diol, or
hydroxycarboxylic acid. Thus, the term "monomer residue", as used
herein, means a residue of a dicarboxylic acid, a diol, or a
hydroxycarboxylic acid. A "repeating unit", as used herein, means
an organic structure having 2 monomer residues bonded through a
carbonyloxy group. The sulfopolyesters of the present invention
contain substantially equal molar proportions of acid residues (100
mole %) and diol residues (100 mole %) which react in substantially
equal proportions such that the total moles of repeating units is
equal to 100 mole %. The mole percentages provided in the present
disclosure, therefore, may be based on the total moles of acid
residues, the total moles of diol residues, or the total moles of
repeating units. For example, a sulfopolyester containing 30 mole %
of a sulfomonomer, which may be a dicarboxylic acid, a diol, or
hydroxycarboxylic acid, based on the total repeating units, means
that the sulfopolyester contains 30 mole % sulfomonomer out of a
total of 100 mole % repeating units. Thus, there are 30 moles of
sulfomonomer residues among every 100 moles of repeating units.
Similarly, a sulfopolyester containing 30 mole % of a dicarboxylic
acid sulfomonomer, based on the total acid residues, means the
sulfopolyester contains 30 mole % sulfomonomer out of a total of
100 mole % acid residues. Thus, in this latter case, there are 30
moles of sulfomonomer residues among every 100 moles of acid
residues.
[0032] The sulfopolyesters described herein have an inherent
viscosity, abbreviated hereinafter as "Ih.V.", of at least about
0.1 dL/g measured in a 60/40 parts by weight solution of
phenol/tetrachloroethane solvent at 25.degree. C. and at a
concentration of about 0.5 g of sulfopolyester in 100 mL of
solvent. The inherent viscosity of the sulfopolyester can also
range from about 0.2 to about 0.3 dL/g. Another range for inherent
viscosity is greater than about 0.3 dL/g. The term "polyester", as
used herein, encompasses both "homopolyesters" and "copolyesters"
and means a synthetic polymer prepared by the polycondensation of
difunctional carboxylic acids with difunctional hydroxyl compound.
As used herein, the term "sulfopolyester" means any polyester
comprising a sulfomonomer.
[0033] Typically the difunctional carboxylic acid is a dicarboxylic
acid and the difunctional hydroxyl compound is a dihydric alcohol
such as, for example glycols and diols. Alternatively, the
difunctional carboxylic acid may be a hydroxy carboxylic acid such
as, for example, p-hydroxybenzoic acid, and the difunctional
hydroxyl compound may be an aromatic nucleus bearing 2 hydroxy
substituents such as, for example, hydroquinone. The term
"residue", as used herein, means any organic structure incorporated
into the polymer through a polycondensation reaction involving the
corresponding monomer. Thus, the dicarboxylic acid residue may be
derived from a dicarboxylic acid monomer or its associated acid
halides, esters, salts, anhydrides, or mixtures thereof. As used
herein, therefore, the term dicarboxylic acid is intended to
include dicarboxylic acids and any derivative of a dicarboxylic
acid, including its associated acid halides, esters, half-esters,
salts, half-salts, anhydrides, mixed anhydrides, or mixtures
thereof, useful in a polycondensation process with a diol to make a
high molecular weight polyester.
[0034] The sulfopolyester of the present invention includes one or
more dicarboxylic acid residues. Depending on the type and
concentration of the sulfomonomer, the dicarboxylic acid residue
may comprise from about 60 to about 100 mole % of the acid
residues. Other examples of concentration ranges of dicarboxylic
acid residues are from about 60 mole % to about 95 mole %, and
about 70 mole % to about 95 mole %. Examples of dicarboxylic acids
that may be used include aliphatic dicarboxylic acids, alicyclic
dicarboxylic acids, aromatic dicarboxylic acids, or mixtures of two
or more of these acids. Thus, suitable dicarboxylic acids include,
but are not limited to, succinic; glutaric; adipic; azelaic;
sebacic; fumaric; maleic; itaconic; 1,3-cyclohexanedicarboxylic;
1,4-cyclohexanedicarboxylic; diglycolic;
2,5-norbornanedicarboxylic; phthalic; terephthalic;
1,4-naphthalenedicarboxylic; 2,5-naphthalenedicarboxylic; diphenic;
4,4'-oxydibenzoic; 4,4'-sulfonyidibenzoic; and isophthalic. The
preferred dicarboxylic acid residues are isophthalic, terephthalic,
and 1,4-cyclohexanedicarboxylic acids, or if diesters are used,
dimethyl terephthalate, dimethyl isophthalate, and
dimethyl-1,4-cyclohexanedicarboxylate. Although the dicarboxylic
acid methyl ester can be utilized, it is also acceptable to include
higher order alkyl esters, such as ethyl, propyl, isopropyl, butyl,
and so forth. In addition, aromatic esters, particularly phenyl,
also may be employed.
[0035] The sulfopolyester includes about 4 to about 40 mole %,
based on the total repeating units, of residues of at least one
sulfomonomer having 2 functional groups and one or more sulfonate
groups attached to an aromatic or cycloaliphatic ring wherein the
functional groups are hydroxyl, carboxyl, or a combination thereof.
Additional examples of concentration ranges for the sulfomonomer
residues are about 4 to about 35 mole %, about 8 to about 30 mole
%, and about 8 to about 25 mole %, based on the total repeating
units. The sulfomonomer may be a dicarboxylic acid or ester thereof
containing a sulfonate group, a diol containing a sulfonate group,
or a hydroxy acid containing a sulfonate group. The term
"sulfonate" refers to a salt of a sulfonic acid having the
structure "--SO.sub.3M" wherein M is the cation of the sulfonate
salt. The cation of the sulfonate salt may be a metal ion such as
Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.++, Ca.sup.++, Ni.sup.++,
Fe.sup.++, and the like. Alternatively, the cation of the sulfonate
salt may be non-metallic such as a nitrogenous base as described,
for example, in U.S. Pat. No. 4,304,901. Nitrogen-based cations are
derived from nitrogen-containing bases, which may be aliphatic,
cycloaliphatic, or aromatic compounds. Examples of such nitrogen
containing bases include ammonia, dimethylethanolamine,
diethanolamine, triethanolamine, pyridine, morpholine, and
piperidine. Because monomers containing the nitrogen-based
sulfonate salts typically are not thermally stable at conditions
required to make the polymers in the melt, the method of this
invention for preparing sulfopolyesters containing nitrogen-based
sulfonate salt groups is to disperse, dissipate, or dissolve the
polymer containing the required amount of sulfonate group in the
form of its alkali metal salt in water and then exchange the alkali
metal cation for a nitrogen-based cation.
[0036] When a monovalent alkali metal ion is used as the cation of
the sulfonate salt, the resulting sulfopolyester is completely
dispersible in water with the rate of dispersion dependent on the
content of sulfomonomer in the polymer, temperature of the water,
surface area/thickness of the sulfopolyester, and so forth. When a
divalent metal ion is used, the resulting sulfopolyesters are not
readily dispersed by cold water but are more easily dispersed by
hot water. Utilization of more than one counterion within a single
polymer composition is possible and may offer a means to tailor or
fine-tune the water-responsivity of the resulting article of
manufacture. Examples of sulfomonomers residues include monomer
residues where the sulfonate salt group is attached to an aromatic
acid nucleus, such as, for example, benzene; naphthalene; diphenyl;
oxydiphenyl; sulfonyldiphenyl; and methylenediphenyl or
cycloaliphatic rings, such as, for example, cyclohexyl;
cyclopentyl; cyclobutyl; cycloheptyl; and cyclooctyl. Other
examples of sulfomonomer residues which may be used in the present
invention are the metal sulfonate salt of sulfophthalic acid,
sulfoterephthalic acid, sulfoisophthalic acid, or combinations
thereof. Other examples of sulfomonomers which may be used are
5-sodiosulfoisophthalic acid and esters thereof. If the
sulfomonomer residue is from 5-sodiosulfoisophthalic acid, typical
sulfomonomer concentration ranges are about 4 to about 35 mole %,
about 8 to about 30 mole %, and about 8 to 25 mole %, based on the
total moles of acid residues.
[0037] The sulfomonomers used in the preparation of the
sulfopolyesters are known compounds and may be prepared using
methods well known in the art. For example, sulfomonomers in which
the sulfonate group is attached to an aromatic ring may be prepared
by sulfonating the aromatic compound with oleum to obtain the
corresponding sulfonic acid and followed by reaction with a metal
oxide or base, for example, sodium acetate, to prepare the
sulfonate salt. Procedures for preparation of various sulfomonomers
are described, for example, in U.S. Pat. Nos. 3,779,993; 3,018,272;
and 3,528,947.
[0038] It is also possible to prepare the polyester using, for
example, a sodium sulfonate salt, and ion-exchange methods to
replace the sodium with a different ion, such as zinc, when the
polymer is in the dispersed form. This type of ion exchange
procedure is generally superior to preparing the polymer with
divalent salts insofar as the sodium salts are usually more soluble
in the polymer reactant melt-phase.
[0039] The sulfopolyester includes one or more diol residues which
may include aliphatic, cycloaliphatic, and aralkyl glycols. The
cycloaliphatic diols, for example, 1,3- and
1,4-cyclohexanedimethanol, may be present as their pure cis or
trans isomers or as a mixture of cis and trans isomers. As used
herein, the term "diol" is synonymous with the term "glycol" and
means any dihydric alcohol. Examples of diols include, but are not
limited to, ethylene glycol; diethylene glycol; triethylene glycol;
polyethylene glycols; 1,3-propanediol;
2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;
2-ethyl-2-butyl-1,3-propanediol;
2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;
1,5-pentanediol; 1,6-hexanediol; 2,2,4-trimethyl-1,6-hexanediol;
thiodiethanol; 1,2-cyclohexanedimethanol;
1,3-cyclohexanedimethanol; 1,4-cyclohexanedimethanol;
2,2,4,4-tetramethyl-1,3-cyclobutanediol; p-xylylenediol, or
combinations of one or more of these glycols.
[0040] The diol residues may include from about 25 mole % to about
100 mole %, based on the total diol residues, of residue of a
poly(ethylene glycol) having a structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH
wherein n is an integer in the range of 2 to about 500.
Non-limiting examples of lower molecular weight polyethylene
glycols, e.g., wherein n is from 2 to 6, are diethylene glycol,
triethylene glycol, and tetraethylene glycol. Of these lower
molecular weight glycols, diethylene and triethylene glycol are
preferred. Higher molecular weight polyethylene glycols
(abbreviated herein as "PEG"), wherein n is from 7 to about 500,
include the commercially available products known under the
designation CARBOWAX.RTM., a product of Dow Chemical Company
(formerly Union Carbide). Typically, PEGs are used in combination
with other diols such as, for example, diethylene glycol or
ethylene glycol. Based on the values of n, which range from greater
than 6 to 500, the molecular weight may range from greater than 300
to about 22,000 g/mol. The molecular weight and the mole % are
inversely proportional to each other; specifically, as the
molecular weight is increased, the mole % will be decreased in
order to achieve a designated degree of hydrophilicity. For
example, it is illustrative of this concept to consider that a PEG
having a molecular weight of 1000 may constitute up to 10 mole % of
the total diol, while a PEG having a molecular weight of 10,000
would typically be incorporated at a level of less than 1 mole % of
the total diol.
[0041] Certain dimer, trimer, and tetramer diols may be formed in
situ due to side reactions that may be controlled by varying the
process conditions. For example, varying amounts of diethylene,
triethylene, and tetraethylene glycols may be formed from ethylene
glycol from an acid-catalyzed dehydration reaction which occurs
readily when the polycondensation reaction is carried out under
acidic conditions. The presence of buffer solutions, well-known to
those skilled in the art, may be added to the reaction mixture to
retard these side reactions. Additional compositional latitude is
possible, however, if the buffer is omitted and the dimerization,
trimerization, and tetramerization reactions are allowed to
proceed.
[0042] The sulfopolyester of the present invention may include from
0 to about 25 mole %, based on the total repeating units, of
residues of a branching monomer having 3 or more functional groups
wherein the functional groups are hydroxyl, carboxyl, or a
combination thereof. Non-limiting examples of branching monomers
are 1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin,
pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol,
trimellitic anhydride, pyromellitic dianhydride, dimethylol
propionic acid, or combinations thereof. Further examples of
branching monomer concentration ranges are from 0 to about 20 mole
% and from 0 to about 10 mole %. The presence of a branching
monomer may result in a number of possible benefits to the
sulfopolyester of the present invention, including but not limited
to, the ability to tailor rheological, solubility, and tensile
properties. For example, at a constant molecular weight, a branched
sulfopolyester, compared to a linear analog, will also have a
greater concentration of end groups that may facilitate
post-polymerization crosslinking reactions. At high concentrations
of branching agent, however, the sulfopolyester may be prone to
gelation.
[0043] The sulfopolyester used for the multicomponent fiber of the
present invention has a glass transition temperature, abbreviated
herein as "Tg", of at least 25.degree. C. as measured on the dry
polymer using standard techniques, such as differential scanning
calorimetry ("DSC"), well known to persons skilled in the art. The
Tg measurements of the sulfopolyesters of the present invention are
conducted using a "dry polymer", that is, a polymer sample in which
adventitious or absorbed water is driven off by heating to polymer
to a temperature of about 200.degree. C. and allowing the sample to
return to room temperature. Typically, the sulfopolyester is dried
in the DSC apparatus by conducting a first thermal scan in which
the sample is heated to a temperature above the water vaporization
temperature, holding the sample at that temperature until the
vaporization of the water absorbed in the polymer is complete (as
indicated by an a large, broad endotherm), cooling the sample to
room temperature, and then conducting a second thermal scan to
obtain the Tg measurement. Further examples of glass transition
temperatures exhibited by the sulfopolyester are at least
30.degree. C., at least 35.degree. C., at least 40.degree. C., at
least 50.degree. C., at least 60.degree. C., at least 65.degree.
C., at least 80.degree. C., and at least 90.degree. C. Although
other glass transition temperatures are possible, typical glass
transition temperatures of the dry sulfopolyesters in our invention
are about 30.degree. C., about 48.degree. C., about 55.degree. C.,
about 65.degree. C., about 70.degree. C., about 75.degree. C.,
about 85.degree. C., and about 90.degree. C.
[0044] In another embodiment, however, the sulfopolyesters of this
invention may be a single polyester or may be blended with one or
more supplemental polymers to modify the properties of the
resulting multicomponent fiber. The supplemental polymer may or may
not be water-dispersible depending on the application and may be
miscible or immiscible with the sulfopolyester. If the supplemental
polymer is water non-dispersible, it is preferred that the blend
with the sulfopolyester is immiscible. The term "miscible", as used
herein, is intended to mean that the blend has a single,
homogeneous amorphous phase as indicated by a single
composition-dependent Tg. For example, a first polymer that is
miscible with second polymer may be used to "plasticize" the second
polymer as illustrated, for example, in U.S. Pat. No. 6,211,309. By
contrast, the term "immiscible", as used herein, denotes a blend
that shows at least 2, randomly mixed, phases and exhibits more
than one Tg. Some polymers may be immiscible and yet compatible
with the sulfopolyester. A further general description of miscible
and immiscible polymer blends and the various analytical techniques
for their characterization may be found in Polymer Blends Volumes 1
and 2, Edited by D. R. Paul and C. B. Bucknall, 2000, John Wiley
& Sons, Inc.
[0045] Non-limiting examples of water-dispersible polymers that may
be blended with the sulfopolyester are polymethacrylic acid,
polyvinyl pyrrolidone, polyethylene-acrylic acid copolymers,
polyvinyl methyl ether, polyvinyl alcohol, polyethylene oxide,
hydroxy propyl cellulose, hydroxypropyl methyl cellulose, methyl
cellulose, ethyl hydroxyethyl cellulose, isopropyl cellulose,
methyl ether starch, polyacrylamides, poly(N-vinyl caprolactam),
polyethyl oxazoline, poly(2-isopropyl-2-oxazoline), polyvinyl
methyl oxazolidone, water-dispersible sulfopolyesters, polyvinyl
methyl oxazolidimone, poly(2,4-dimethyl-6-triazinylethylene), and
ethylene oxide-propylene oxide copolymers. Examples of polymers
which are water non-dispersible that may be blended with the
sulfopolyester include, but are not limited to, polyolefins, such
as homo- and copolymers of polyethylene and polypropylene;
poly(ethylene terephthalate); poly(butylene terephthalate); and
polyamides, such as nylon-6; polylactides; caprolactone; Eastar
Bios (poly(tetramethylene adipate-co-terephthalate), a product of
Eastman Chemical Company); polycarbonate; polyurethane; and
polyvinyl chloride.
[0046] According to our invention, blends of more than one
sulfopolyester may be used to tailor the end-use properties of the
resulting nonwoven fabric or web. The blends of one or more
sulfopolyesters will have glass transition temperatures of at least
25.degree. C. Thus, blending may also be exploited to alter the
processing characteristics of a sulfopolyester to facilitate the
fabrication of the nonwoven fabric.
[0047] The sulfopolyester and supplemental polymer may be blended
in batch, semicontinuous, or continuous processes. Small scale
batches may be readily prepared in any high-intensity mixing
devices well-known to those skilled in the art, such as Banbury
mixers, prior to melt-spinning fibers. The components may also be
blended in solution in an appropriate solvent. The melt blending
method includes blending the sulfopolyester and supplemental
polymer at a temperature sufficient to melt the polymers. The blend
may be cooled and pelletized for further use or the melt blend can
be melt spun directly from this molten blend into fiber form. The
term "melt" as used herein includes, but is not limited to, merely
softening the polyester. For melt mixing methods generally known in
the polymers art, see Mixing and Compounding of Polymers (I.
Manas-Zloczower & Z. Tadmor editors, Carl Hanser Verlag
Publisher, 1994, New York, N.Y.).
[0048] In another embodiment of the invention, the sulfopolyester
in the multicomponent fiber has a glass transition temperature (Tg)
of at least 25.degree. C., and the sulfopolyester comprises:
(A) about 50 to about 96 mole % of one or more residues of
isophthalic acid or terephthalic acid, based on the total acid
residues; (B) about 4 to about 30 mole %, based on the total acid
residues, of a residue of sodiosulfoisophthalic acid; (C) one or
more diol residues wherein at least 25 mole %, based on the total
diol residues, is a poly(ethylene glycol) having a structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH
wherein n is an integer in the range of 2 to about 500; (iv) 0 to
about 20 mole %, based on the total repeating units, of residues of
a branching monomer having 3 or more functional groups wherein the
functional groups are hydroxyl, carboxyl, or a combination thereof.
As described hereinabove, the multicomponent fiber may optionally
include a first water-dispersible polymer blended with the
sulfopolyester; and,
[0049] optionally, a water non-dispersible polymer blended with the
sulfopolyester such that the blend is an immiscible blend. The
first water-dispersible polymer is as described hereinabove. The
sulfopolyester can have a glass transition temperature (Tg) of at
least 25.degree. C., but may have, for example, a Tg of about
35.degree. C., about 48.degree. C., about 55.degree. C., about
65.degree. C., about 70.degree. C., about 75.degree. C., about
85.degree. C., and about 90.degree. C. The sulfopolyester may
contain other concentrations of isophthalic acid residues, for
example, about 60 to about 95 mole %, and about 75 to about 95 mole
%. Further examples of isophthalic acid residue concentrations
ranges are about 70 to about 85 mole %, about 85 to about 95 mole %
and about 90 to about 95 mole %. The sulfopolyester also may
comprise about 25 to about 95 mole % of the residues of diethylene
glycol. Further examples of diethylene glycol residue concentration
ranges include about 50 to about 95 mole %, about 70 to about 95
mole %, and about 75 to about 95 mole %. The sulfopolyester also
may include the residues of ethylene glycol and/or
1,4-cyclohexanedimethanol, abbreviated herein as "CHDM". Typical
concentration ranges of CHDM residues are about 10 to about 75 mole
%, about 25 to about 65 mole %, and about 40 to about 60 mole %.
Typical concentration ranges of ethylene glycol residues are about
10 to about 75 mole %, about 25 to about 65 mole %, and about 40 to
about 60 mole %. In another embodiment, the sulfopolyester
comprises about 75 to about 96 mole % of the residues of
isophthalic acid and about 25 to about 95 mole % of the residues of
diethylene glycol.
[0050] The sulfopolyesters of the instant invention are readily
prepared from the appropriate dicarboxylic acids, esters,
anhydrides, or salts, sulfomonomer, and the appropriate diol or
diol mixtures using typical polycondensation reaction conditions.
They may be made by continuous, semi-continuous, and batch modes of
operation and may utilize a variety of reactor types. Examples of
suitable reactor types include, but are not limited to, stirred
tank, continuous stirred tank, slurry, tubular, wiped-film, falling
film, or extrusion reactors. The term "continuous" as used herein
means a process wherein reactants are introduced and products
withdrawn simultaneously in an uninterrupted manner. By
"continuous" it is meant that the process is substantially or
completely continuous in operation and is to be contrasted with a
"batch" process. "Continuous" is not meant in any way to prohibit
normal interruptions in the continuity of the process due to, for
example, start-up, reactor maintenance, or scheduled shut down
periods. The term "batch" process as used herein means a process
wherein all the reactants are added to the reactor and then
processed according to a predetermined course of reaction during
which no material is fed or removed into the reactor. The term
"semicontinuous" means a process where some of the reactants are
charged at the beginning of the process and the remaining reactants
are fed continuously as the reaction progresses. Alternatively, a
semicontinuous process may also include a process similar to a
batch process in which all the reactants are added at the beginning
of the process except that one or more of the products are removed
continuously as the reaction progresses. The process is operated
advantageously as a continuous process for economic reasons and to
produce superior coloration of the polymer as the sulfopolyester
may deteriorate in appearance if allowed to reside in a reactor at
an elevated temperature for too long a duration.
[0051] The sulfopolyesters of the present invention are prepared by
procedures known to persons skilled in the art. The sulfomonomer is
most often added directly to the reaction mixture from which the
polymer is made, although other processes are known and may also be
employed, for example, as described in U.S. Pat. Nos. 3,018,272,
3,075,952, and 3,033,822. The reaction of the sulfomonomer, diol
component and the dicarboxylic acid component may be carried out
using conventional polyester polymerization conditions.
[0052] For example, when preparing the sulfopolyesters by means of
an ester interchange reaction, i.e., from the ester form of the
dicarboxylic acid components, the reaction process may comprise two
steps. In the first step, the diol component and the dicarboxylic
acid component, such as, for example, dimethyl isophthalate, are
reacted at elevated temperatures, typically, about 150.degree. C.
to about 250.degree. C. for about 0.5 to about 8 hours at pressures
ranging from about 0.0 kPa gauge to about 414 kPa gauge (60 pounds
per square inch, "psig"). Preferably, the temperature for the ester
interchange reaction ranges from about 180.degree. C. to about
230.degree. C. for about 1 to about 4 hours while the preferred
pressure ranges from about 103 kPa gauge (15 psig) to about 276 kPa
gauge (40 psig).
[0053] Thereafter, the reaction product is heated under higher
temperatures and under reduced pressure to form sulfopolyester with
the elimination of diol, which is readily volatilized under these
conditions and removed from the system. This second step, or
polycondensation step, is continued under higher vacuum and a
temperature which generally ranges from about 230.degree. C. to
about 350.degree. C., preferably about 250.degree. C. to about
310.degree. C. and most preferably about 260.degree. C. to about
290.degree. C. for about 0.1 to about 6 hours, or preferably, for
about 0.2 to about 2 hours, until a polymer having the desired
degree of polymerization, as determined by inherent viscosity, is
obtained. The polycondensation step may be conducted under reduced
pressure which ranges from about 53 kPa (400 torr) to about 0.013
kPa (0.1 torr). Stirring or appropriate conditions are used in both
stages to ensure adequate heat transfer and surface renewal of the
reaction mixture. The reactions of both stages are facilitated by
appropriate catalysts such as, for example, alkoxy titanium
compounds, alkali metal hydroxides and alcoholates, salts of
organic carboxylic acids, alkyl tin compounds, metal oxides, and
the like. A three-stage manufacturing procedure, similar to that
described in U.S. Pat. No. 5,290,631, may also be used,
particularly when a mixed monomer feed of acids and esters is
employed.
[0054] To ensure that the reaction of the diol component and
dicarboxylic acid component by an ester interchange reaction
mechanism is driven to completion, it is preferred to employ about
1.05 to about 2.5 moles of diol component to one mole dicarboxylic
acid component. Persons of skill in the art will understand,
however, that the ratio of diol component to dicarboxylic acid
component is generally determined by the design of the reactor in
which the reaction process occurs.
[0055] In the preparation of sulfopolyester by direct
esterification, i.e., from the acid form of the dicarboxylic acid
component, sulfopolyesters are produced by reacting the
dicarboxylic acid or a mixture of dicarboxylic acids with the diol
component or a mixture of diol components. The reaction is
conducted at a pressure of from about 7 kPa gauge (1 psig) to about
1379 kPa gauge (200 psig), preferably less than 689 kPa (100 psig)
to produce a low molecular weight, linear or branched
sulfopolyester product having an average degree of polymerization
of from about 1.4 to about 10. The temperatures employed during the
direct esterification reaction typically range from about
180.degree. C. to about 280.degree. C. Another range is from about
220.degree. C. to about 270.degree. C. This low molecular weight
polymer may then be polymerized by a polycondensation reaction.
[0056] The multicomponent fibers, nonwoven fabrics, and fibrous
articles of this invention also may contain other conventional
additives and ingredients which do not deleteriously affect their
end use. For example, additives such as fillers, surface friction
modifiers, light and heat stabilizers, extrusion aids, antistatic
agents, colorants, dyes, pigments, fluorescent brighteners,
antimicrobials, anticounterfeiting markers, hydrophobic and
hydrophilic enhancers, viscosity modifiers, slip agents,
tougheners, adhesion promoters, and the like may be used.
[0057] The multicomponent fibers, nonwoven fabrics, and fibrous
articles of our invention do not require the presence of additives
such as, for example, pigments, fillers, oils, waxes, or fatty acid
finishes, to prevent blocking or fusing of the fibers during
processing. The terms "blocking or fusing", as used herein, is
understood to mean that the fibers or fibrous articles stick
together or fuse into a mass such that the fiber cannot be
processed or used for its intended purpose. Blocking and fusing can
occur during processing of the fiber or fibrous article or during
storage over a period of days or weeks and is exacerbated under
hot, humid conditions.
[0058] In one embodiment of the invention, the multicomponent
fibers, nonwoven fabrics, and fibrous articles can contain less
than 10 wt % of such anti-blocking additives, based on the total
weight of the multicomponent fiber or fibrous article. For example,
the multicomponent fibers and fibrous articles may contain less
than 10 wt % of a pigment or filler. In other examples, the
multicomponent fibers, nonwoven fabrics, and fibrous articles may
contain less than 9 wt %, less than 5 wt %, less than 3 wt %, less
than 1 wt %, and 0 wt % of a pigment or filler, based on the total
weight of the multicomponent fiber. Colorants, sometimes referred
to as toners, may be added to impart a desired neutral hue and/or
brightness to the sulfopolyester. When colored multicomponent
fibers are desired, pigments or colorants may be included in the
sulfopolyester reaction mixture during the reaction of the diol
monomer and the dicarboxylic acid monomer or they may be melt
blended with the preformed sulfopolyester. A preferred method of
including colorants is to use a colorant having thermally stable
organic colored compounds having reactive groups such that the
colorant is copolymerized and incorporated into the sulfopolyester
to improve its hue. For example, colorants such as dyes possessing
reactive hydroxyl and/or carboxyl groups, including, but not
limited to, blue and red substituted anthraquinones, may be
copolymerized into the polymer chain. When dyes are employed as
colorants, they may be added to the copolyester reaction process
after an ester interchange or direct esterification reaction.
[0059] In one embodiment of the invention, the sulfopolyesters
contained in the multicomponent fiber has a glass transition
temperature (Tg) of at least 57.degree. C. A glass transition
temperature (Tg) of at least 57.degree. C. has been found to
particularly useful for multicomponent fibers to prevent blocking
and fusing of the multicomponent fiber during spinning and take up.
Thus, in one embodiment of the invention, a multicomponent fiber
having shaped cross section is utilized to produce the nonwoven
fabric comprising:
(A) a water dispersible sulfopolyester having a glass transition
temperature (Tg) of at least 57.degree. C., the sulfopolyester
comprising:
[0060] (i) residues of one or more dicarboxylic acids;
[0061] (ii) about 4 to about 40 mole %, based on the total
repeating units, of residues of at least one sulfomonomer having 2
functional groups and one or more sulfonate groups attached to an
aromatic or cycloaliphatic ring wherein the functional groups are
hydroxyl, carboxyl, or a combination thereof;
[0062] (iii) one or more diol residues wherein at least 25 mole %,
based on the total diol residues, is a poly(ethylene glycol) having
a structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH [0063] wherein n is an integer
in the range of 2 to about 500; and
[0064] (iv) 0 to about 25 mole %, based on the total repeating
units, of residues of a branching monomer having 3 or more
functional groups wherein the functional groups are hydroxyl,
carboxyl, or a combination thereof; and
(B) a plurality of segments comprising one or more water
non-dispersible polymers immiscible with the sulfopolyester,
wherein the segments are substantially isolated from each other by
the sulfopolyester intervening between the segments;
[0065] wherein the fiber has an islands-in-the-sea or segmented pie
cross section.
[0066] The dicarboxylic acids, diols, sulfopolyester,
sulfomonomers, and branching monomers residues are as described
previously for other embodiments of the invention. For
multicomponent fibers, it is advantageous that the sulfopolyester
have a Tg of at least 57.degree. C. Further examples of glass
transition temperatures that may be exhibited by the sulfopolyester
or sulfopolyester blend of the multicomponent fiber are at least
60.degree. C., at least 65.degree. C., at least 70.degree. C., at
least 75.degree. C., at least 80.degree. C., at least 85.degree.
C., and at least 90.degree. C. Further, to obtain a sulfopolyester
with a Tg of at least 57.degree. C., blends of one or more
sulfopolyesters may be used in varying proportions to obtain a
sulfopolyester blend having the desired Tg. The Tg of a
sulfopolyester blend may be calculated by using a weighted average
of the glass transition temperatures of the sulfopolyester
components. For example, sulfopolyester having a Tg of 48.degree.
C. may be blended in a 25:75 wt:wt ratio with another
sulfopolyester having Tg of 65.degree. C. to give a sulfopolyester
blend having a Tg of approximately 61.degree. C.
[0067] In another embodiment of the invention, the water
dispersible sulfopolyester component of the multicomponent fiber
presents properties which allow at least one of the following:
(A) the multicomponent fibers to be spun to a desired low denier,
and (B) the multicomponent fibers are heat settable to yield a
stable, strong nonwoven fabric. Surprising and unexpected results
were achieved in furtherance of these objectives using a
sulfopolyester having a certain melt viscosity and level of
sulfomonomer residues. Therefore, in this embodiment of the
invention, a multicomponent fiber is utilized having a shaped cross
section comprising: (A) at least one water dispersible
sulfopolyester; and (B) a plurality of domains comprising one or
more water non-dispersible polymers immiscible with the
sulfopolyester, wherein said domains are substantially isolated
from each other by the sulfopolyester intervening between the
domains,
[0068] wherein the multicomponent fiber has an as-spun denier of
less than about 6 denier per filament;
[0069] wherein the water dispersible sulfopolyester exhibits a melt
viscosity of less than about 12,000 poise measured at 240.degree.
C. at a strain rate of 1 rad/sec, and wherein the sulfopolyester
comprises less than about 25 mole % of residues of at least one
sulfomonomer, based on the total moles of diacid or diol
residues.
[0070] The sulfopolyester utilized in these multicomponent fibers
has a melt viscosity of generally less than about 12,000 poise.
Other ranges of melt viscosity of the sulfopolyester is less than
10,000 poise, less than 6,000, and less than 4,000 poise measured
at 240.degree. C. and 1 rad/sec shear rate. In another aspect, the
sulfopolyester exhibits a melt viscosity ranging from about 1000 to
about 12000 poise, from about 2000 to about 6000 poise, or from
about 2500 to about 4000 poise measured at 240.degree. C. and 1
rad/sec shear rate. Prior to determining the viscosity, the samples
are dried at 60.degree. C. in a vacuum oven for 2 days. The melt
viscosity is measured using a rheometer having a 25 mm diameter
parallel-plate geometry at 1 mm gap setting. A dynamic frequency
sweep is run at a strain rate range of 1 to 400 rad/sec and 10%
strain amplitude. The viscosity is then measured at 240.degree. C.
and strain rate of 1 rad/sec.
[0071] The level of sulfomonomer residues in the sulfopolyester
polymers for use in this embodiment of the invention is generally
less than about 25 mole % or less than 20 mole %, reported as a
percentage of the total diacid or diol residues in the
sulfopolyester. Other ranges for the level of sulfomonomer residues
in the sulfopolyester polymers range from about 4 to about 20 mole
%, about 5 to about 12 mole %, and between about 7 to about 10 mole
%. In another aspect of this embodiment, the sulfomonomers for use
with the invention can have 2 functional groups and one or more
sulfonate groups attached to an aromatic or cycloaliphatic ring
wherein the functional groups are hydroxyl, carboxyl, or a
combination thereof, for example, sodiosulfo-isophthalic acid
monomer.
[0072] In addition to the sulfomonomer described previously, the
sulfopolyester can comprise residues of one or more dicarboxylic
acids, one or more diol residues wherein at least 25 mole %, based
on the total diol residues, is a poly(ethylene glycol) having a
structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH
wherein n is an integer in the range of 2 to about 500, and 0 to
about 20 mole %, based on the total repeating units, of residues of
a branching monomer having 3 or more functional groups wherein the
functional groups are hydroxyl, carboxyl, or a combination
thereof.
[0073] In one embodiment of the invention, the sulfopolyester
comprises from about 80-96 mole % dicarboxylic acid residues, from
about 4 to about 20 mole % sulfomonomer residues, and 100 mole %
diol residues (there being a total mole % of 200%, i.e., 100 mole %
diacid and 100 mole % diol). More specifically, the dicarboxylic
portion of the sulfopolyester comprises between about 60-80 mole %
terephthalic acid, about 0-30 mole % isophthalic acid, and about
4-20 mole % 5-sodiosulfoisophthalic acid (5-SSIPA). The diol
portion comprises from about 0-50 mole % diethylene glycol and from
about 50-100 mole % ethylene glycol. An exemplary formulation
according to this embodiment of the invention is set forth
subsequently.
TABLE-US-00001 Approximate Mole % (based on total moles of diol or
diacid residues) Terephthalic acid 71 Isophthalic acid 20 5-SSIPA 9
Diethylene glycol 35 Ethylene glycol 65
[0074] The water non-dispersible component of the multicomponent
fiber may comprise any of those water non-dispersible polymers
described herein. Spinning of the multicomponent fiber may also
occur according to any method described herein. However, the
improved rheological properties of multicomponent fibers in
accordance with this aspect of the invention provide for enhanced
drawings speeds. When the water dispersible sulfopolyester has a
melt viscosity of less than about 12,000 poise measured at
240.degree. C. at a strain rate of 1 rad/sec, and wherein the
sulfopolyester comprises less than about 25 mole % of residues of
at least one sulfomonomer, based on the total moles of diacid or
diol residues, and is extruded to produce multicomponent
extrudates, the multicomponent extrudate is capable of being melt
drawn to produce the multicomponent fiber, using any of the methods
disclosed herein, at a speed of at least about 2000 m/min. In
another aspect of this embodiment, the multicomponent extrudate is
capable of being melt drawn at a speed in the following ranges: at
least about 3000 m/min, at least about 4000 m/min, or at least
about 4500 m/min. Although not intending to be bound by theory,
melt drawing of the multicomponent extrudates at these speeds
results in at least some oriented crystallinity in the water
non-dispersible component of the multicomponent fiber. This
oriented crystallinity can increase the dimensional stability of
nonwoven fabrics made from the multicomponent fibers during
subsequent processing.
[0075] Another advantage of the multicomponent extrudate produced
from sulfopolyesters having a melt viscosity of less than about
12,000 poise measured at 240.degree. C. at a strain rate of 1
rad/sec, and wherein the sulfopolyester comprises less than about
25 mole % of residues of at least one sulfomonomer, based on the
total moles of diacid or diol residues, is that it can be melt
drawn to a multicomponent fiber having an as-spun denier of less
than 6 deniers per filament. Other ranges of multicomponent fiber
sizes include an as-spun denier of less than 4 deniers per filament
and less than 2.5 deniers per filament.
[0076] The multicomponent fiber comprises a plurality of segments
or domains of one or more water non-dispersible polymers immiscible
with the sulfopolyester in which the segments or domains are
substantially isolated from each other by the sulfopolyester
intervening between the segments or domains. The term
"substantially isolated", as used herein, is intended to mean that
the segments or domains are set apart from each other to permit the
segments domains to form individual fibers upon removal of the
sulfopolyester. For example, the segments or domains may be
touching each others as in, for example, a segmented pie
configuration but can be split apart by impact or when the
sulfopolyester is removed.
[0077] The ratio by weight of the sulfopolyester to water
non-dispersible polymer component in the multicomponent fiber of
the invention is generally in the range of about 60:40 to about
2:98 or, in another example, in the range of about 50:50 to about
5:95. Typically, the sulfopolyester comprises 50% by weight or less
of the total weight of the multicomponent fiber.
[0078] The segments or domains of the multicomponent fiber comprise
one of more water non-dispersible polymers. Examples of water
non-dispersible polymers which are used in segments of the
multicomponent fiber include, but are not limited to, polyolefins,
polyesters, polyamides, polylactides, polycaprolactone,
polycarbonate, polyurethane, and polyvinyl chloride. For example,
the water non-dispersible polymer may be polyester such as
poly(ethylene) terephthalate, poly(butylene) terephthalate,
poly(cyclohexylene) cyclohexanedicarboxylate, poly(cyclohexylene)
terephthalate, poly(trimethylene) terephthalate, and the like.
[0079] In one embodiment of the invention, the water
non-dispersible polymer is poly(ethylene) terephthalate having an
inherent viscosity of less than 0.6 dL/g, measured in a 60/40 parts
by weight solution of phenol/tetrachloroethane solvent at
25.degree. C. and at a concentration of about 0.5 g of
poly(ethylene) terephthalate in 100 mL of solvent. Other ranges are
less than 0.55 dL/g, less than 0.4_dL/g, and less than 0.3 dL/g.
PET having this inherent viscosity can produce improved nonwoven
fabrics having good fiber entanglement and less loose fibers on the
surface of the nonwoven fabric.
[0080] In another example, the water non-dispersible polymer can be
biodistintegratable as determined by DIN Standard 54900 and/or
biodegradable as determined by ASTM Standard Method, D6340-98.
Examples of biodegradable polyesters and polyester blends are
disclosed in U.S. Pat. Nos. 5,599,858; 5,580,911; 5,446,079; and
5,559,171. The term "biodegradable", as used herein in reference to
the water non-dispersible polymers of the present invention, is
understood to mean that the polymers are degraded under
environmental influences such as, for example, in a composting
environment, in an appropriate and demonstrable time span as
defined, for example, by ASTM Standard Method, D6340-98, entitled
"Standard Test Methods for Determining Aerobic Biodegradation of
Radiolabeled Plastic Materials in an Aqueous or Compost
Environment". The water non-dispersible polymers of the present
invention also may be "biodisintegratable", meaning that the
polymers are easily fragmented in a composting environment as
defined, for example, by DIN Standard 54900. For example, the
biodegradable polymer is initially reduced in molecular weight in
the environment by the action of heat, water, air, microbes and
other factors. This reduction in molecular weight results in a loss
of physical properties (tenacity) and often in fiber breakage. Once
the molecular weight of the polymer is sufficiently low, the
monomers and oligomers are then assimilated by the microbes. In an
aerobic environment, these monomers or oligomers are ultimately
oxidized to CO.sub.2, H.sub.2O, and new cell biomass. In an
anaerobic environment, the monomers or oligomers are ultimately
converted to CO.sub.2, H.sub.2, acetate, methane, and cell
biomass.
[0081] For example, water non-dispersible polymer may be an
aliphatic-aromatic polyester, abbreviated herein as "AAPE". The
term "aliphatic-aromatic polyester", as used herein, means a
polyester comprising a mixture of residues from aliphatic or
cycloaliphatic dicarboxylic acids or diols and aromatic
dicarboxylic acids or diols. The term "non-aromatic", as used
herein with respect to the dicarboxylic acid and diol monomers of
the present invention, means that carboxyl or hydroxyl groups of
the monomer are not connected through an aromatic nucleus. For
example, adipic acid contains no aromatic nucleus in its backbone,
i.e., the chain of carbon atoms connecting the carboxylic acid
groups, thus is "non-aromatic". By contrast, the term "aromatic"
means the dicarboxylic acid or diol contains an aromatic nucleus in
the backbone such as, for example, terephthalic acid or
2,6-naphthalene dicarboxylic acid. "Non-aromatic", therefore, is
intended to include both aliphatic and cycloaliphatic structures
such as, for example, diols and dicarboxylic acids, which contain
as a backbone a straight or branched chain or cyclic arrangement of
the constituent carbon atoms which may be saturated or paraffinic
in nature, unsaturated, i.e., containing non-aromatic carbon-carbon
double bonds, or acetylenic, i.e., containing carbon-carbon triple
bonds. Thus, in the context of the description and the claims of
the present invention, non-aromatic is intended to include linear
and branched, chain structures (referred to herein as "aliphatic")
and cyclic structures (referred to herein as "alicyclic" or
"cycloaliphatic"). The term "non-aromatic", however, is not
intended to exclude any aromatic substituents which may be attached
to the backbone of an aliphatic or cycloaliphatic diol or
dicarboxylic acid. In the present invention, the difunctional
carboxylic acid typically is a aliphatic dicarboxylic acid such as,
for example, adipic acid, or an aromatic dicarboxylic acid such as,
for example, terephthalic acid. The difunctional hydroxyl compound
may be cycloaliphatic diol such as, for example,
1,4-cyclohexanedimethanol, a linear or branched aliphatic diol such
as, for example, 1,4-butanediol, or an aromatic diol such as, for
example, hydroquinone.
[0082] The AAPE may be a linear or branched random copolyester
and/or chain extended copolyester comprising diol residues which
comprise the residues of one or more substituted or unsubstituted,
linear or branched, diols selected from aliphatic diols containing
2 to about 8 carbon atoms, polyalkylene ether glycols containing 2
to 8 carbon atoms, and cycloaliphatic diols containing about 4 to
about 12 carbon atoms. The substituted diols, typically, will
comprise 1 to about 4 substituents independently selected from
halo, C.sub.6-C.sub.10 aryl, and C.sub.1-C.sub.4 alkoxy. Examples
of diols which may be used include, but are not limited to,
ethylene glycol, diethylene glycol, propylene glycol,
1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol,
1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, polyethylene
glycol, diethylene glycol, 2,2,4-trimethyl-1,6-hexanediol,
thio-diethanol, 1,3-cyclohexanedimethanol,
1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol,
triethylene glycol, and tetraethylene glycol with the preferred
diols comprising one or more diols selected from 1,4-butanediol;
1,3-propanediol; ethylene glycol; 1,6-hexanediol; diethylene
glycol; or 1,4-cyclohexanedimethanol. The AAPE also comprises
diacid residues which contain about 35 to about 99 mole %, based on
the total moles of diacid residues, of the residues of one or more
substituted or unsubstituted, linear or branched, non-aromatic
dicarboxylic acids selected from aliphatic dicarboxylic acids
containing 2 to about 12 carbon atoms and cycloaliphatic acids
containing about 5 to about 10 carbon atoms. The substituted
non-aromatic dicarboxylic acids will typically contain 1 to about 4
substituents selected from halo, C.sub.6-C.sub.10 aryl, and
C.sub.1-C.sub.4 alkoxy. Non-limiting examples of non-aromatic
diacids include malonic, succinic, glutaric, adipic, pimelic,
azelaic, sebacic, fumaric, 2,2-dimethyl glutaric, suberic,
1,3-cyclopentanedicarboxylic, 1,4-cyclohexane-dicarboxylic,
1,3-cyclohexanedicarboxylic, diglycolic, itaconic, maleic, and
2,5-norbornanedicarboxylic. In addition to the non-aromatic
dicarboxylic acids, the AAPE comprises about 1 to about 65 mole %,
based on the total moles of diacid residues, of the residues of one
or more substituted or unsubstituted aromatic dicarboxylic acids
containing 6 to about 10 carbon atoms. In the case where
substituted aromatic dicarboxylic acids are used, they will
typically contain 1 to about 4 substituents selected from halo,
C.sub.6-C.sub.10 aryl, and C.sub.1-C.sub.4 alkoxy. Non-limiting
examples of aromatic dicarboxylic acids which may be used in the
AAPE of our invention are terephthalic acid, isophthalic acid,
salts of 5-sulfoisophthalic acid, and 2,6-naphthalenedicarboxylic
acid. More preferably, the non-aromatic dicarboxylic acid will
comprise adipic acid, the aromatic dicarboxylic acid will comprise
terephthalic acid, and the diol will comprise 1,4-butanediol.
[0083] Other possible compositions for the AAPE's of our invention
are those prepared from the following diols and dicarboxylic acids
(or polyester-forming equivalents thereof such as diesters) in the
following mole percentages, based on 100 mole percent of a diacid
component and 100 mole percent of a diol component: [0084] (1)
glutaric acid (about 30 to about 75%); terephthalic acid (about 25
to about 70%); 1,4-butanediol (about 90 to 100%); and modifying
diol (0 about 10%); [0085] (2) succinic acid (about 30 to about
95%); terephthalic acid (about 5 to about 70%); 1,4-butanediol
(about 90 to 100%); and modifying diol (0 to about 10%); and [0086]
(3) adipic acid (about 30 to about 75%); terephthalic acid (about
25 to about 70%); 1,4-butanediol (about 90 to 100%); and modifying
diol (0 to about 10%).
[0087] The modifying diol preferably is selected from
1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol
and neopentyl glycol. The most preferred AAPE's are linear,
branched or chain extended copolyesters comprising about 50 to
about 60 mole percent adipic acid residues, about 40 to about 50
mole percent terephthalic acid residues, and at least 95 mole
percent 1,4-butanediol residues. Even more preferably, the adipic
acid residues comprise about 55 to about 60 mole percent, the
terephthalic acid residues comprise about 40 to about 45 mole
percent, and the diol residues comprise about 95 mole percent
1,4-butanediol residues. Such compositions are commercially
available under the trademark EASTAR BIO.RTM. copolyester from
Eastman Chemical Company, Kingsport, Tenn., and under the trademark
ECOFLEX.RTM. from BASF Corporation.
[0088] Additional, specific examples of preferred AAPE's include a
poly(tetra-methylene glutarate-co-terephthalate) containing (a) 50
mole percent glutaric acid residues, 50 mole percent terephthalic
acid residues, and 100 mole percent 1,4-butanediol residues, (b) 60
mole percent glutaric acid residues, 40 mole percent terephthalic
acid residues, and 100 mole percent 1,4-butanediol residues or (c)
40 mole percent glutaric acid residues, 60 mole percent
terephthalic acid residues, and 100 mole percent 1,4-butanediol
residues; a poly(tetramethylene-succinate-co-terephthalate)
containing (a) 85 mole percent succinic acid residues, 15 mole
percent terephthalic acid residues, and 100 mole percent
1,4-butanediol residues or (b) 70 mole percent succinic acid
residues, 30 mole percent terephthalic acid residues, and 100 mole
percent 1,4-butanediol residues; a poly(ethylene
succinate-co-terephthalate) containing 70 mole percent succinic
acid residues, 30 mole percent terephthalic acid residues, and 100
mole percent ethylene glycol residues; and a poly(tetramethylene
adipate-co-terephthalate) containing (a) 85 mole percent adipic
acid residues, 15 mole percent terephthalic acid residues, and 100
mole percent 1,4-butanediol residues; or (b) 55 mole percent adipic
acid residues, 45 mole percent terephthalic acid residues, and 100
mole percent 1,4-butanediol residues.
[0089] The AAPE preferably comprises from about 10 to about 1,000
repeating units and preferably, from about 15 to about 600
repeating units. The AAPE may have an inherent viscosity of about
0.4 to about 2.0 dL/g, or more preferably about 0.7 to about 1.6
dL/g, as measured at a temperature of 25.degree. C. using a
concentration of 0.5 gram copolyester in 100 ml of a 60/40 by
weight solution of phenol/tetrachloroethane.
[0090] The AAPE, optionally, may contain the residues of a
branching agent. The mole percentage ranges for the branching agent
are from about 0 to about 2 mole %, preferably about 0.1 to about 1
mole %, and most preferably about 0.1 to about 0.5 mole % based on
the total moles of diacid or diol residues (depending on whether
the branching agent contains carboxyl or hydroxyl groups). The
branching agent preferably has a weight average molecular weight of
about 50 to about 5000, more preferably about 92 to about 3000, and
a functionality of about 3 to about 6. The branching agent, for
example, may be the esterified residue of a polyol having 3 to 6
hydroxyl groups, a polycarboxylic acid having 3 or 4 carboxyl
groups (or ester-forming equivalent groups) or a hydroxy acid
having a total of 3 to 6 hydroxyl and carboxyl groups. In addition,
the AAPE may be branched by the addition of a peroxide during
reactive extrusion.
[0091] Each segment of the water non-dispersible polymer may be
different from others in fineness and may be arranged in any shaped
or engineered cross-sectional geometry known to persons skilled in
the art. For example, the sulfopolyester and a water
non-dispersible polymer may be used to prepare a multicomponent
fiber having an engineered geometry such as, for example, a
side-by-side, "islands-in-the-sea", segmented pie, other
splitables, sheath/core, or other configurations known to persons
skilled in the art. Other multi-component configurations are also
possible. Subsequent removal of a side, the "sea", or a portion of
the "pie" can result in very fine fibers. The process of preparing
multicomponent fibers also is well known to persons skilled in the
art. In a multicomponent fiber, the sulfopolyester fibers of this
invention may be present in amounts of about 10 to about 90 weight
% and will generally be used in the sheath portion of sheath/core
fibers. The other component may be from a wide range of other
polymeric materials such as, for example, poly(ethylene)
terephthalate, poly(butylene) terephthalate, poly(trimethylene)
terephthalate, polylactides and the like as well as polyolefins,
cellulose esters, and polyamides. Typically, when a water-insoluble
or water non-dispersible polymer is used, the resulting bicomponent
or multicomponent fiber is not completely water-dispersible. Side
by side combinations with significant differences in thermal
shrinkage can be utilized for the development of a spiral crimp. If
crimping is desired, a saw tooth or stuffer box crimp is generally
suitable for many applications. If the second polymer component is
in the core of a sheath/core configuration, such a core optionally
may be stabilized.
[0092] The sulfopolyesters are particularly useful for fibers
having an "islands-in-the-sea" or "segmented pie" cross section as
they only requires neutral or slightly acidic (i.e., "soft" water)
to disperse, as compared to the caustic-containing solutions that
are sometimes required to remove other water dispersible polymers
from multicomponent fibers. Thus, another aspect of our invention
is when the multicomponent fiber comprises:
(A) a water dispersible sulfopolyester having a glass transition
temperature (Tg) of at least 57.degree. C., the sulfopolyester
comprising:
[0093] (i) about 50 to about 96 mole % of one or more residues of
isophthalic acid or terephthalic acid, based on the total acid
residues;
[0094] (ii) about 4 to about 30 mole %, based on the total acid
residues, of a residue of sodiosulfoisophthalic acid;
[0095] (iii) one or more diol residues wherein at least 25 mole %,
based on the total diol residues, is a poly(ethylene glycol) having
a structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH
[0096] wherein n is an integer in the range of 2 to about 500;
[0097] (iv) 0 to about 20 mole %, based on the total repeating
units, of residues of a branching monomer having 3 or more
functional groups wherein the functional groups are hydroxyl,
carboxyl, or a combination thereof; and
(B) a plurality of segments comprising one or more water
non-dispersible polymers immiscible with the sulfopolyester,
wherein the segments are substantially isolated from each other by
the sulfopolyester intervening between the segments;
[0098] wherein the fiber has an islands-in-the-sea or segmented pie
cross section.
The dicarboxylic acids, diols, sulfopolyester, sulfomonomers,
branching monomers residues, and water non-dispersible polymers are
as described previously. For multicomponent fibers, it is
advantageous that sulfopolyester have a Tg of at least 57.degree.
C. The sulfopolyester may be a single sulfopolyester or a blend of
one or more sulfopolyester polymers. Further examples of glass
transition temperatures that may be exhibited by the sulfopolyester
or sulfopolyester blends are at least 65.degree. C., at least
70.degree. C., at least 75.degree. C., at least 85.degree. C., and
at least 90.degree. C. For example, the sulfopolyester may comprise
about 75 to about 96 mole % of one or more residues of isophthalic
acid or terephthalic acid and about 25 to about 95 mole % of a
residue of diethylene glycol. As described hereinabove, examples of
the water non-dispersible polymers are polyolefins, polyesters,
polyamides, polylactides, polycaprolactone, polycarbonate,
polyurethane, and polyvinyl chloride. In addition, the water
non-dispersible polymer may be biodegradable or biodisintegratable.
For example, the water non-dispersible polymer may be an
aliphatic-aromatic polyester as described previously.
[0099] The multicomponent fiber may be prepared by any number of
methods known to persons skilled in the art. In one embodiment of
the invention, the multicomponent fiber having a shaped cross
section is produced by a process comprising: spinning a water
dispersible sulfopolyester having a glass transition temperature
(Tg) of at least 57.degree. C. and one or more water
non-dispersible polymers immiscible with the sulfopolyester into a
fiber, the sulfopolyester comprising:
[0100] (i) residues of one or more dicarboxylic acids;
[0101] (ii) about 4 to about 40 mole %, based on the total
repeating units, of residues of at least one sulfomonomer having 2
functional groups and one or more sulfonate groups attached to an
aromatic or cycloaliphatic ring wherein the functional groups are
hydroxyl, carboxyl, or a combination thereof;
[0102] (iii) one or more diol residues wherein at least 25 mole %,
based on the total diol residues, is a poly(ethylene glycol) having
a structure
H--(OCH.sub.2--CH.sub.2).sub.n--OH
[0103] wherein n is an integer in the range of 2 to about 500;
and
[0104] (iv) 0 to about 25 mole %, based on the total repeating
units, of residues of a branching monomer having 3 or more
functional groups wherein the functional groups are hydroxyl,
carboxyl, or a combination thereof; wherein the fiber has a
plurality of segments comprising the water non-dispersible polymers
and the segments are substantially isolated from each other by the
sulfopolyester intervening between the segments.
[0105] For example, the multicomponent fiber may be prepared by
melting the sulfopolyester and one or more water non-dispersible
polymers in separate extruders and directing the individual polymer
flows into one spinneret or extrusion die with a plurality of
distribution flow paths such that the water non-dispersible polymer
component form small segments or thin strands which are
substantially isolated from each other by the intervening
sulfopolyester. The cross section of such a fiber may be, for
example, a segmented pie arrangement or an islands-in-the-sea
arrangement. In another example, the sulfopolyester and one or more
water non-dispersible polymers are separately fed to the spinneret
orifices and then extruded in sheath-core form in which the water
non-dispersible polymer forms a "core" that is substantially
enclosed by the sulfopolyester "sheath" polymer. In the case of
such concentric fibers, the orifice supplying the "core" polymer is
in the center of the spinning orifice outlet and flow conditions of
core polymer fluid are strictly controlled to maintain the
concentricity of both components when spinning. Modifications in
spinneret orifices enable different shapes of core and/or sheath to
be obtained within the fiber cross-section. In yet another example,
a multicomponent fiber having a side-by-side cross section or
configuration may be produced by coextruding the water dispersible
sulfopolyester and water non-dispersible polymer through orifices
separately and converging the separate polymer streams at
substantially the same speed to merge side-by-side as a combined
stream below the face of the spinneret; or (2) by feeding the two
polymer streams separately through orifices, which converge at the
surface of the spinneret, at substantially the same speed to merge
side-by-side as a combined stream at the surface of the spinneret.
In both cases, the velocity of each polymer stream, at the point of
merge, is determined by its metering pump speed, the number of
orifices, and the size of the orifice.
[0106] The dicarboxylic acids, diols, sulfopolyester,
sulfomonomers, branching monomers residues, and water
non-dispersible polymers are as described previously. The
sulfopolyester has a glass transition temperature of at least
57.degree. C. Further examples of glass transition temperatures
that may be exhibited by the sulfopolyester or sulfopolyester blend
are at least 65.degree. C., at least 70.degree. C., at least
75.degree. C., at least 85.degree. C., and at least 90.degree. C.
In one example, the sulfopolyester may comprise about 50 to about
96 mole % of one or more residues of isophthalic acid or
terephthalic acid, based on the total acid residues; and about 4 to
about 30 mole %, based on the total acid residues, of a residue of
sodiosulfoisophthalic acid; and 0 to about 20 mole %, based on the
total repeating units, of residues of a branching monomer having 3
or more functional groups wherein the functional groups are
hydroxyl, carboxyl, or a combination thereof. In another example,
the sulfopolyester may comprise about 75 to about 96 mole % of one
or more residues of isophthalic acid or terephthalic acid and about
25 to about 95 mole % of a residue of diethylene glycol. As
described hereinabove, examples of the water non-dispersible
polymers are polyolefins, polyesters, polyamides, polylactides,
polycaprolactone, polycarbonate, polyurethane, and polyvinyl
chloride. In addition, the water non-dispersible polymer may be
biodegradable or biodisintegratable. For example, the water
non-dispersible polymer may be an aliphatic-aromatic polyester as
described previously. Examples of shaped cross sections include,
but are not limited to, islands-in-the-sea, side-by-side,
sheath-core, or segmented pie configurations.
[0107] In another embodiment of the invention, the multicomponent
fiber having a shaped cross section is produced by a process
comprising: spinning at least one water dispersible sulfopolyester
and one or more water non-dispersible polymers immiscible with the
sulfopolyester to produce a multicomponent fiber, wherein the
multicomponent fiber has a plurality of domains comprising the
water non-dispersible polymers and the domains are substantially
isolated from each other by the sulfopolyester intervening between
the domains; wherein the water dispersible sulfopolyester exhibits
a melt viscosity of less than about 12,000 poise measured at
240.degree. C. at a strain rate of 1 rad/sec, and wherein the
sulfopolyester comprising less than about 25 mole % of residues of
at least one sulfomonomer, based on the total moles of diacid or
diol residues; and wherein the multicomponent fiber has an as-spun
denier of less than about 6 denier per filament.
[0108] The sulfopolyester utilized in these multicomponent fiber
and the water non-dispersible polymers were discussed previously in
this disclosure.
[0109] In another embodiment of this invention, the multicomponent
fiber having a shaped cross section can be produced by a process
comprising:
(A) extruding at least one water dispersible sulfopolyester and one
or more water non-dispersible polymers immiscible with said
sulfopolyester to produce a multicomponent extrudate, wherein the
multicomponent extrudate has a plurality of domains comprising the
water non-dispersible polymers and the domains are substantially
isolated from each other by the sulfopolyester intervening between
the domains; and (B) melt drawing the multicomponent extrudate at a
speed of at least about 2000 m/min to produce the multicomponent
fiber.
[0110] It is also a feature of this embodiment that the process
includes the step of melt drawing the multicomponent extrudate at a
speed of at least about 2000 m/min, more preferably, at least about
3000 m/min, and most preferably at least 4500 m/min.
[0111] Typically, upon exiting the spinneret, the fibers are
quenched with a cross flow of air whereupon the fibers solidify.
Various finishes and sizes may be applied to the fiber at this
stage. The cooled fibers, typically, are subsequently drawn and
wound up on a take up spool. Other additives may be incorporated in
the finish in effective amounts like emulsifiers, antistatics,
antimicrobials, antifoams, lubricants, thermostabilizers, UV
stabilizers, and the like.
[0112] Optionally, the drawn fibers may be textured and wound-up to
form a bulky continuous filament. This one-step technique is known
in the art as spin-draw-texturing. Other embodiments include flat
filament (non-textured) yarns, or cut staple fiber, either crimped
or uncrimped.
[0113] Step (A) of the inventive process comprises collecting the
multicomponent fibers to form a non-woven web. The multicomponents
fibers produced by the processes discussed previously can be
collected in a manner to produce a nonwoven web such that a support
for the multicomponent fibers is not necessary. This can be
accomplished by any method known in the art. For example, the
multicomponent fibers can be subjected to such processes as
mechanical needling, chemical binding, thermally calendaring,
ultrasonic fusing, or hydroentangling, in order to provide enough
consolidation where a support for the multicomponent fibers is not
necessary. An example of mechanical needling is needle
punching.
[0114] In one embodiment of the invention, when hydroentangling is
chosen to consolidate or bond the multicomponent fibers only
sufficient hydroentangling is conducted in this step such that a
support is not necessary for the multicomponent fibers. In one
embodiment of the invention, the amount of hydroentangling energy
expended in this process can range from about 20% to about 50% of
the hydroentangling energy expended in Step (C) of the process. As
will be discussed later in this invention, hydroentangling after
sulfopolyester removal, (Step C) of the process, is the step where
the majority of the energy is expended to interlock the
multicomponent fibers to produce the nonwoven fabric. Since the
fibers are finer when the sulfopolyester is removed, this provides
for an improved nonwoven fabric and also requires less
hydroentangling energy than traditional systems that hydroentangle
fibers prior to sulfopolyester removal.
[0115] In another embodiment of the invention, extrusion technology
can be utilized to produce the nonwoven web of Step (A) from the
materials used to make the multicomponent fibers themselves, thus
eliminating the multicomponent fiber production step. These
processes include spunbond and meltblown processes. The spunbond
process transforms the water dispersible sulfopolyester and water
non-dispersible polymer directly into a nonwoven web by extruding
multicomponent fibers, orienting them as bundles or groupings, and
layering them on a conveying screen, without a separate fiber
production step. In conventional processes, the multicomponent
fiber is first spun and collected, then formed into a fabric by a
separate process. Therefore, the water dispersible sulfopolyester
and water non-dispersible polymer are routed through the spunbond
process to yield a nonwoven web of Step (A). FIG. 1 shows the
spunbond process. In the meltblown process, the water dispersible
sulfopolyester and water non-dispersible polymer are heated to the
liquid state and as it passes through an extrusion orifice, it is
injected with sonic velocity air at about 250 to 500.degree. C. The
fast moving air stream stretches the molten polymer and solidifies
it to produce fine multicomponent fibers. The multicomponent fibers
are then separated from the air stream as an entangled web and
compressed between heated rolls to produce the nonwoven web of Step
(A).
[0116] Generally, the weight of the nonwoven web can range from
about 10 grams/m.sup.2 to about 800 grams/m.sup.2. Other ranges are
10 grams/m.sup.2 to 600 grams/m.sup.2, 10 grams/m.sup.2 to 400
grams/m.sup.2, 50 gram s/m.sup.2 to 300 grams/m.sup.2
grams/m.sup.2, and about 50 grams/m.sup.2 to about 150
grams/m.sup.2.
[0117] Step (B) of the inventive process comprises contacting the
nonwoven web with water at a sufficient extraction temperature and
pressure to remove a portion of the water dispersible
sulfopolyester thereby forming a microfiber web. Typically, the
multicomponent fiber can be contacted with water at an extraction
temperature of about 20.degree. C. to about 100.degree. C. Other
extraction temperature ranges are from 25.degree. C. to about
100.degree. C. and from about 40.degree. C. to about 90.degree.
C.
[0118] The extraction temperature is defined by the following
procedure. A nonwoven web consisting of multicomponent fibers with
a known water dispersible sulfopolyester content is weighed and
then taped to a metal backing plate and covered with a 100-200 mesh
stainless steel screen on top. The backing plate with nonwoven
fabric is placed in a deionized water bath at a test temperature in
the range about 20.degree. C. to about 60.degree. C. for 10 minutes
to extract the water dispersible sulfopolyester. After the
conditioning, the specimen is removed from the water, and the
excess water is removed by placing an absorbent towel above the
screen mesh and squeezing. The conditioned fabric web is dried in a
forced air oven at 60.degree. C. and the final weight is measured.
The weight loss due to extraction is calculated as a percentage of
the starting weight. The temperature of the conditioning water at
which greater than 80% of the sulfopolyester polymer in the
starting fiber is removed during the conditioning is designated as
the sulfopolyester extraction temperature.
[0119] Generally, the temperature, pressure, contact time of the
water are such that the water dispersible sulfopolyester is
removed, and the nonwoven web remains sufficiently intact as a
structure. The pressure of the water can range from about 30 barr
to about 600 barr. Other pressure ranges are 50 barr to 300
barr.
[0120] In one embodiment of the invention, the nonwoven web can be
contacted with water for a time sufficient to remove about 30% by
weight to about 100% by weight of the total water dispersible
sulfopolyester contained in the multicomponent fiber. In another
embodiment of the invention, greater than 90% by weight of the
total water dispersible sulfopolyester is removed from the nonwoven
web. In another embodiment, greater than 95% by weight of the total
water dispersible sulfopolyester is removed from the nonwoven
web.
[0121] In another embodiment, the nonwoven web is contacted with
water for a time period of from about 10 to about 600 seconds
whereby the water dispersible sulfopolyester is dissipated or
dissolved.
[0122] After removal of the sulfopolyester, the remaining water
non-dispersible polymer microfibers can have an average fineness of
less than 30% of the denier of the starting multicomponent fiber.
The remaining water non-dispersible polymer microfibers typically
will have an average fineness of 1 d/f or less, typically, 0.5 d/f
or less, or more typically, 0.11 d/f or less.
[0123] Generally, the nonwoven web is contacted with water via any
method known in the art. For example, water jets can be utilized.
In one embodiment of the invention, one to eight water jet heads
can be utilized. The amount of water used ranges from less than 500
times to less than 1000 times the weight of the nonwoven web prior
to contacting with water.
[0124] The wash water containing the water-dispersible
sulfopolyester can be recycled. In one embodiment of the invention,
80% or more of the wash water is recycled. This is quite an
advancement since in conventional processes to produce nonwoven
fabrics, the wash water generally cannot be recycled due to the
water dispersible sulfopolyester that may plug equipment and may
cause excess machine wear. In another embodiment of the invention,
substantially all of the sulfopolyester is removed from the wash
water. Sulfopolyester recycling processes are described in U.S.
patent application Ser. No. 11/343,955 filed Jan. 31.sup.st, 2006
to Gupta entitled "Sulfopolyester Recovery", which is hereby
incorporated by reference to the extent it does not contradict the
statements herein.
[0125] Step (C) comprises hydroentangling the microfiber web to
produce the nonwoven fabric. Generally, the water temperature
during hydroentangling is less than 40.degree. C. The pressure can
range from about 150 bar to about 220 bar. During this
hydroentangling step, less than 1% by weight of the water
dispersible sulfopolyester is removed from the microfiber web. In
other embodiments of the invention, the amount of water dispersible
sulfopolyester removed can be less than 0.8% by weight, less than
0.5% by weight, less than 0.25% by weight, less than 0.1% by
weight, less than 0.08% by weight, less than 0.05% by weight, and
less than 0.02% by weight based on the weight of the microfiber
web. The water from the hydroentangling step can be recycled also
as discussed previously. Due to the low level of water-dispersible
sulfopolyester, the sulfopolyester may not need to be removed from
the wash water before reuse.
[0126] In one embodiment of the invention, the hydroentangling is
conducted by water jets. The number of waterjet heads can range
from 1 to about 20, or from 2 to about 15, or 2 to about 10.
Because a substantial amount of the sulfopolyester has been
removed, the fibers contained in the microfiber web are much finer,
and during the hydroentangling step, a superior nonwoven fabric is
produced having a tighter configuration with less fraying and loose
fibers.
[0127] In addition, the hydroentangling process of this invention
can be simplified over conventional nonwoven hydroentangling
processes where hydroentangling occurs prior to removal of the
water-dispersible polymer. Since the water non-dispersible polymer
fibers in the microfiber web are finer, less hydraulic energy is
needed to entangle the fibers. Furthermore, in conventional
nonwoven processes, hydroentangling typically occurs prior to the
removal of the water-dispersible sulfopolyester, and often times,
further hydroentangling after removal of the sulfopolyester is
required. However, in the present invention, a quality nonwoven
fabric can be obtained without a further hydroentangling step.
[0128] In another embodiment of the invention, a process for making
a nonwoven fabric is provided comprising: [0129] (A) collecting
multicomponent fibers to form a non-woven web; wherein the
multicomponent fiber comprises at least one water dispersible
sulfopolyester and at least one water non-dispersible polymer;
wherein the multicomponent fiber has a plurality of domains
comprising the water non-dispersible polymer; wherein the domains
are substantially isolated from each other by the water dispersible
sulfopolyester intervening between the domains; and [0130] (B)
contacting the non-woven web with water at a sufficient temperature
and pressure to remove a portion of said sulfopolyester thereby
forming a microfibers and simultaneously hydroentangling the
microfibers to produce the nonwoven fabric. Steps (A) and (B) have
been previously described in this disclosure.
[0131] The non-woven fabric can under go a heat setting step
comprising heating the non-woven fabric to a temperature of at
least about 100.degree. C., and more preferably at least about
120.degree. C. The heat setting step relaxes out internal fiber
stresses and aids in producing a dimensionally stable fabric
product. It is preferred that when the heat set material is
reheated to the temperature to which it was heated during the heat
setting step that it exhibits surface area shrinkage of less than
about 5% of its original surface area. More preferably, the
shrinkage is less than about 2% of the original surface area, and
most preferably the shrinkage is less than about 1%.
[0132] The nonwoven fabric can optionally be held together by 1)
mechanical fiber cohesion and interlocking in a web or mat; 2)
various techniques of fusing of fibers, including the use of binder
fibers, utilizing the thermoplastic properties of certain polymers
and polymer blends; 3) use of a binding resin such as starch,
casein, a cellulose derivative, or a synthetic resin, such as an
acrylic latex or urethane; 4) powder adhesive binders; or 5)
combinations thereof. The fibers in the nonwoven fabric are often
deposited in a random manner, although orientation in one direction
is possible, followed by bonding using one of the methods described
above.
[0133] The instant invention produces nonwoven fabrics that can be
utilized in clothing, curtains, upholstery, and uniforms. Nonwoven
fabrics can also be utilized in personal care products, such as,
but not limited to, wipes, feminine hygiene products, baby diapers,
training pants, adult incontinence briefs, and hospital/surgical
and other medical disposables, such as, but not limited to,
surgical gowns, gauzes, bandages and the like. Other applications
include, but are not limited to, multilayer nonwovens, laminates
and composites, protective fabrics and layers, geotextiles,
industrial wipes, and filter media. Further, the fibrous articles
may include replacement inserts for various personal hygiene and
cleaning products. The fibrous article of the present invention may
be bonded, laminated, attached to, or used in conjunction with
other materials which may or may not be water-dispersible. The
fibrous article, for example, a nonwoven fabric layer, may be
bonded to a flexible plastic film or backing of a water
non-dispersible material, such as polyethylene. Such an assembly,
for example, could be used as one component of a disposable
diaper.
EXAMPLES
[0134] The multicomponent fibers and nonwoven fabrics described in
the following examples were produced in the manner described below.
A pilot scale bicomponent spunbond line capable of producing a 0.5
meter wide nonwoven fabric was used to spin the multicomponent
fibers and produce the nonwoven fabrics used in the listed
examples. A simplified process diagram of the spunbond line is
shown in FIG. 1. The specific details of this process are described
subsequently.
[0135] Separate extruders and spin pumps were utilized to melt and
meter the water dispersible sulfopolyester and the PET into the
bicomponent spin pack. One extruder melted and metered the water
dispersible sulfopolyester and the second extruder melted and
metered the PET polymer. In this process, the water dispersible
sulfopolyester was extruded at a melt temperature of 260.degree.
C., and the PET component was extruded at a 285.degree. C. melt
temperature. The total combined polymer flow was about 1.33
kg/min., resulting in an average polymer flow rate exiting each die
hole of about 0.60 grams/hole per minute from a spinneret having
2222 holes.
[0136] Both polymer melt streams entered a segmented pie
bicomponent spin pack (manufactured by Hills Inc., Melbourne, Fla.)
which distributed the polymer melts such that the final combined
melt stream was in the form of 2222 multicomponent fibers having
the segmented pie polymer distribution. The lobes contained the PET
component while the area between these lobes is comprised of the
water dispersible sulfopolyester co-extruded with the PET during
this fiber spinning process. The spinneret in this spin pack was
constructed with 2222 die holes each having a diameter of 0.35
millimeters.
[0137] An aspirator assembly using compressed air was utilized to
form a high velocity downward flow stream which drew the extruded
polymer melt streams exiting the spinneret into fine multicomponent
fibers. In the present examples, sufficient air pressure was
applied to draw the multicomponent fibers to a fineness of about
1.0 to about 1.5 denier per filament (dpf) or nominal filament
diameters of about 8 to about 12 microns.
[0138] The drawn fibers were laid down on a collection belt to form
a continuous nonwoven web where the density (basis weight) of the
nonwoven web was controlled by the speed of the belt and the
extrusion rate. Nonwoven webs having a typical basis weight of
about 100 to about 150 grams/sq. meter or as specified were
produced in the examples.
[0139] A compacting roll and wind up station was utilized to
produce rolls of the lightly compacted nonwoven webs of
multicomponent fibers with the segmented pie fiber cross-section
structure. The compaction of the nonwoven web was conducted using
calendar rolls at room temperature with sufficient nip pressure to
consolidate the nonwoven web so it could be handled on a roll and
unwound for further treatment.
[0140] The nonwoven web produced by the preceding process was
subsequently hydroentangled using a pilot scale hydroentangling
line (manufactured by Fleissner, Engelsbach, Germany) having five
hydroentangling heads. The hydroentangling equipment was utilized
in the examples using different number of hydroentangling heads and
pressures as specified in the examples. The hydroentangling
equipment had three high pressure hydroentangling heads which
contacted the nonwoven web as it passed under the water jets
supported by a 103 mesh screen belt. The first head operated as a
pre-wetting station using only about 30 bar water pressure while
hydroentangling heads 2 and 3 were operated at a typical water
pressure ranging from about 100 to about 200 bar. The water jets of
the final two hydroentangling heads impacted the nonwoven web as it
was conveyed on a hydroentangling drum with a porous surface
capable of drawing the water from the hydroentangling jets into the
drum using vacuum within the drum. These final two hydroentangling
jets were operated at about 200 bar water pressure, and the jets
contacted the side of the fabric opposite the side contacted by the
first three hydroentangling jets.
[0141] In each hydroentangling head, a jet strip was inserted which
consisted of a line of finely machined holes having a diameter of
about 120 microns with a separation between holes of about 0.8 mm.
The water pressure of about 200 bar on one side of the jet strip
inside the hydroentangling head caused a high velocity jet of water
to be formed in each hole. These high velocity water jets caused
the multicomponent fibers in the nonwoven web to entangle as the
web passes under the hydroentangling jets. In operation about 1200
water jets are applied per meter of nonwoven web width and
typically the water flow through a jet strip is about 150
liters/minute or about 0.12 liter/min. of water flowing through
each individual hole in the jet strip. During the hydroentangling
process, the nonwoven web was passed under the hydroentangling jets
at a speed ranging from about 10 meters/min. to about 50
meters/min. The fabric speed can be adjusted to vary the degree of
hydroentangling treatment. The temperature of the water during the
hydroentangling process was about 30.degree. C.-40.degree. C. and
no treatment of the process water such as deionization or
demineralization was performed. The hydroentangling process water
used in these examples was inherently low in metal ion content. In
practice, demineralization of the water used in the hydroentangling
operation is desirable.
[0142] These process details are general and apply to the specific
pilot equipment available for production of the fabrics of the
following examples. The conditions described are not meant to be
limiting, rather to serve to demonstrate how the materials
described in the examples could be produced using other types of
nonwoven fabric equipment than the specific equipment used in the
examples.
Example 1
Preparation of the Nonwoven Web
[0143] A nonwoven web comprised of bicomponent fibers having a
segmented pie structure with 16 segments was prepared according to
the procedure previously described. The non water dispersible
component of the bicomponent fibers was F53HC grade of PET
polyester with inherent viscosity of about 0.53 (Eastman Chemical
Company, Kingsport, Tenn., U.S.A.) and extruded along with a water
dispersible sulfopolyester as the second component. The water
dispersible sulfopolyester had designation SP05F Lot TP06038931
(Eastman Chemical Company) and exhibited a melt viscosity of about
3000 poise as measured at 240.degree. C. and 1 rad/sec shear
rate.
[0144] Both polymers were extruded through a segmented pie
bicomponent spin pack (Hills Inc., Melbourne Fla.) with a spinneret
having 2222 holes at a total extrusion rate through each hole of
about 0.6 grams/hole-min (ghm) with the two polymers in a 70 (PET)
to 30 (sulfopolyester) weight ratio. The molten fiber extrudates
were drawn using an aspirator assembly to form fibers with an
average fiber diameter of about 9 microns having the desired
segmented pie polymer distribution. The extruded multicomponent
fibers were laid down onto a forming belt to produce a nonwoven web
having a basis weight of 135 grams/sq. meter (gsm).
[0145] The nonwoven web of Example 1 was consolidated by pressing
between calendar rolls at room temperature. The multicomponent
fibers were melt drawn at an estimated speed in excess of about
5000 meters/min during this process. When the nonwoven web of
Example 1 was conditioned unrestricted in an oven at 120.degree.
C., the nonwoven web shrank to 60%.times.57% of the starting
dimensions in the MD (machine direction) and CD (cross direction)
respectively due to stress relaxation of the multicomponent
fibers.
[0146] This nonwoven web had minimal inter-fiber bonding and served
as the precursor for producing hydroentangled nonwoven fabrics by
subsequent processing of this nonwoven web of Example 1.
Example 2
[0147] The nonwoven web of Example 1 was hydroentangled with high
velocity water jets using a hydroentangling unit described
previously. During the hydroentangling process, the fabric passed
through the machine at a 40 meters/min. speed where the nonwoven
web was exposed to two high pressure hydroentangling jets operating
with 150 bar water pressure. The first jet was applied to the
nonwoven web as it was transported on a 103 mesh screen belt to
apply a fine mesh pattern to the nonwoven web. The second
hydroentangling jet was applied to the opposite side of the web as
it was supported on a hydroentangling drum operating under vacuum
to yield the nonwoven fabric.
[0148] In the final step of the hydroentangling process, the wet
nonwoven fabric was passed through a drum dryer where 70.degree. C.
air passed through the nonwoven fabric by the action of vacuum
maintained within the 1.4 meter diameter drum. In the process, the
nonwoven fabric was only partly dried when heated in the oven and
exited in the wet state. The residence time of the nonwoven fabric
in the oven was measured to be about 5 seconds. As the nonwoven
fabric was wound onto a core, some excess water was squeezed out,
and it was noted that the water was cloudy due to the presence of
emulsified sulfopolyester and also formed a sticky film when dried.
Both observations indicated that some of sulfopolyester was
emulsified during this drying step.
[0149] The energy expended during the hydroentangling process is
inversely proportional to the speed of the nonwoven fabric passing
under the jets where slower speed translates to increased
hydroentangling energy applied to the nonwoven fabric. Similarly,
the energy applied is directly proportional to the number of
hydroentangling jet stations under which the nonwoven fabric passes
where the hydroentangling energy applied by each jet station is
proportional to the square root of the water pressure. Using these
relationships, the relative amount of hydroentangling energy
applied to a nonwoven web can be approximated for comparison. In
the present case of Example 2, the hydroentangling energy is
arbitrarily assigned a value of 1.0, where in subsequent examples
the value will represent the increase in hydroentangling energy
applied to the nonwoven web relative to the process in Example
2
[0150] The basis weight of the hydroentangled nonwoven fabric of
Example 2 was 139 gsm (on dry basis), which was similar to the
value of the starting nonwoven web and indicated that none or only
minimal sulfopolyester was removed during hydroentangling.
[0151] The wet nonwoven fabric of Example 2 was rinsed 3 times in
ambient temperature deionized water to remove the sulfopolyester
emulsified in the water phase soaked in the nonwoven fabric. After
rinsing and drying, a soft nonwoven fabric was recovered. The
nonwoven fabric recovered was very loose, exhibited limited
strength, and had a fuzzy texture due to loose fiberson fabric
surface. The nonwoven fabric had limited utility as a textile
fabric. The weight loss during rinsing steps was 29% indicating
about full removal of water dispersible sulfopolyester from the
nonwoven fabric.
[0152] This nonwoven fabric of Example 2 had limited utility as a
finished product but consisted of a nonwoven web of microfibers
where the sulfopolyester was removed from the multicomponent fibers
to expose the PET microfibers. This precursor nonwoven fabric of
Example 2 was further processed to make nonwoven fabrics of
subsequent examples 5 and 7.
Example 3
[0153] The nonwoven web of Example 1 was hydroentangled with high
velocity water jets using a hydroentangling unit described
previously. During the hydroentangling process, the nonwoven web
passed through the unit at 10 meters/min speed where the nonwoven
web was exposed to four high pressure hydroentangling jets
operating with jet pressures of 100 bar, 150 bar, 200 bar, and 200
bar, respectively. The first two jets were applied to the nonwoven
web as it was transported on a 103 mesh screen belt to apply a fine
mesh pattern to the nonwoven web. The third and fourth
hydroentangling jets were applied to the opposite side of the
nonwoven web as it was supported on a hydroentangling drum
operating under vacuum to produce the nonwoven fabric.
[0154] In the final step of the hydroentangling process, the wet
nonwoven fabric was passed through a drum dryer where 70.degree. C.
air passed through the nonwoven fabric by the action of vacuum
maintained within the 1.4 meter diameter drum. In the process, the
nonwoven fabric was only partly dried when heated in the oven and
exited in the wet state. The residence time of the nonwoven fabric
in the oven was measured to be about 18 seconds. As the nonwoven
fabric was wound, some excess water was squeezed out, and it was
noted that the water was cloudy due to the presence of emulsified
sulfopolyester. The emulsified sulfopolyester also formed a sticky
film on the nonwoven fabric when dried.
[0155] The energy expended during the hydroentangling process is
inversely proportional to the speed of the nonwoven fabric passing
under the jets where slower speed translates to increased
hydroentangling energy applied to the nonwoven fabric. Similarly,
the energy applied is directly proportional to the number of
hydroentangling jet stations under which the nonwoven fabric passes
where the hydroentangling energy applied by each jet station is
proportional to the square root of the water pressure. Using these
relationships, the relative amount of hydroentangling energy
applied to this nonwoven web of Example 3 relative to Example 2 was
calculated for comparison. In the present case, the hydroentangling
energy amounted to a value 8.3 times larger than the base value
assigned to Example 2. The higher degree of hydroentanglement in
Example 3 is due to 2 times the number of hydroentanglement jets
used coupled with a 1/4 process line speed which provided 4 times
the residence time under the hydroentanglement jets.
[0156] The basis weight of the hydroentangled nonwoven fabric of
Example 3 was 136 gsm, which was similar to the value of the
starting nonwoven web of Example 1 and indicated that none or only
minimal amount of sulfopolyester was removed during
hydroentangling.
[0157] The wet nonwoven fabric of Example 3 was rinsed 3 times in
ambient temperature deionized water to remove any sulfopolyester
emulsified in the water phase soaked in the nonwoven fabric. After
rinsing and drying, a soft nonwoven fabric was recovered. A weight
loss of about 28% was observed indicating removal of essentially
all of sulfopolyester from the nonwoven fabric. This nonwoven
fabric was very flexible, exhibited good strength, but had a fuzzy
surface texture due to loose surface fibers. This precursor fabric
of Example 3 was used for further processing to make fabrics of
Examples 6 and 9.
Example 4
[0158] The wet nonwoven fabric of Example 2 was passed through a
hydroentangling unit described previously using minimal water
contact in order to remove the sulfopoyester from the nonwoven
fabric without applying much additional entanglement of the
multicomponent fibers in the fabric. As noted in Example 2, the
sulfopolyester in the nonwoven fabric was found to be present in
the absorbed water phase rather than the multicomponent fibers, and
a simple water rinse was found to remove the sulfopolyester from
the nonwoven fabric. The nonwoven fabric passed through the
hydroentangling unit at a 50 meters/min. speed where the nonwoven
fabric was exposed to a single high pressure hydroentangling jets
operating at 100 bar pressure. The temperature of the water during
the process was about 20.degree. C.
[0159] The fabric of Example 4 was dried at ambient temperatures
and subsequently washed at 50.degree. C. in deionized water to
calculate the amount of residual sulfopolyester in the nonwoven
fabric that was not removed by the single water jet of the process
of Example 4. Only a 3.0% weight loss was measured after washing
the nonwoven fabric of Example 4 indicating that about 90% by
weight of the sulfopolyester in the nonwoven fabric of Example 2
was removed by this single head hydroentangling step. The single
water head was effective for removing the bulk of sulfopolyester in
the nonwoven fabric and removal would have been more efficient if
the temperature was higher, preferably in the range of about
40.degree. C. to about 50.degree. C. for sulfopolyester
removal.
Example 5
[0160] The precursor nonwoven fabric of Example 2 was further
hydroentangled with high velocity water jets using the
hydroentangling unit described previously. During this subsequent
second hydroentangling step, the precursor nonwoven fabric of
Example 2 was passed through the hydroentangling unit at a speed of
10 meters/min and was exposed to four high pressure hydroentangling
jets operating with jet pressures of 130 bar, 150 bar, 200 bar, and
200 bar respectively. The first two jets were applied to the
nonwoven fabric as it was transported on a 61 mesh screen belt
obtained from Asten Johnson in Charleston, S.C. to apply a mesh
pattern to the nonwoven fabric. The third and fourth
hydroentangling jets were applied to the opposite side of the
nonwoven fabric as it was supported on a hydroentangling drum
operating under vacuum.
[0161] Using the relationships previously described, the relative
amount of hydroentangling energy applied to this nonwoven fabric in
the process of Example 5 relative to the process of Example 2 was
calculated for comparison. The hydroentangling energy in Example 5
amounts to a value 8.5 times larger than the base value of 1
assigned to Example 2. The overall hydroentanglement energy applied
to the nonwoven fabric in the combined process of Example 2 and 5
amounts to a value about 9.5 times the hydroentangling energy
applied in the process of Example 2 alone. This fabric exhibited
very good fiber entanglement with no loose fibers on the surface.
This fabric exhibited good smooth surface texture.
Example 6
[0162] The precursor nonwoven fabric of Example 3 was further
hydroentangled with high velocity water jets using the
hydroentangling unit. During this second hydroentangling step, the
nonwoven fabric passed through the hydroentangling unit at a speed
of 10 meters/min where the nonwoven fabric was exposed to four high
pressure hydroentangling jets operating with jet pressures of 130
bar, 150 bar, 200 bar, and 200 bar, respectively. The first two
jets were applied to the nonwoven fabric of Example 3 as it was
transferred on a 61 mesh screen belt obtained from Asten Johnson to
apply a mesh pattern to the fabric. The third and fourth
hydroentangling jets were applied to the opposite side of the
nonwoven fabric as it was supported on a hydroentangling drum
operating under vacuum.
[0163] Using the relationships previously described, the relative
amount of hydroentangling energy applied to this nonwoven fabric in
the process of Example 6 relative to the process of Example 2 was
calculated for comparison. The hydroentangling energy in Example 6
amounts to a value 8.5 times larger than the arbitrary value
assigned to Example 2. The overall hydroentanglement energy applied
to the nonwoven fabric in the combined process of Example 3 and 6
amounts to a value about 16.8 times the hydroentangling energy
applied in the process of Example 2 alone. This fabric exhibited
very good fiber entanglement with no loose fibers on the surface.
This fabric exhibited good smooth surface texture.
Example 7
[0164] The precursor nonwoven fabric of Example 2 was further
hydroentangled with high velocity water jets using the
hydroentangling unit. During this second hydroentangling step, the
nonwoven fabric passed through the hydroentangling unit at a speed
of 10 meters/min where the nonwoven fabric was exposed to four high
pressure hydroentangling jets operating with jet pressures of 130
bar, 150 bar, 200 bar, and 200 bar, respectively. The first two
jets were applied to the nonwoven fabric as it was transported on a
Formtec 14 (14 mesh screen) belt obtained from Albany International
in Albany, N.Y. to apply a coarse mesh pattern to the nonwoven
fabric. The difference between the fabric of Example 5 and the
fabric of Example 7 is the forming belt used, where the belt in
Example 7 conferred a coarser basket weave appearance to the fabric
surface compared to the fabric of Example 5. The third and fourth
hydroentangling jets were applied to the opposite side of the
nonwoven fabric as it was supported on a hydroentangling drum
operating under vacuum.
[0165] Using the relationships previously described, the relative
amount of hydroentangling energy applied to this nonwoven fabric in
the process of Example 7 relative to the process of Example 2 was
calculated for comparison. The hydroentangling energy in Example 7
amounts to a value 8.5 times larger than the arbitrary value of 1
assigned to Example 2. The overall hydroentanglement energy applied
to the nonwoven fabric in the combined process of Example 2 and 7
amounts to a value about 9.5 times the hydroentangling energy
applied in the process of Example 2 alone. This fabric exhibited
very good fiber entanglement with no loose fibers on the surface.
This fabric exhibited good smooth surface texture.
Example 8
[0166] The nonwoven fabric of Example 5 was heat set by placing
pieces of fabric on a restraining frame and conditioning the
nonwoven fabric in a forced air oven at 130.degree. C. for 5
minutes conditioning time. The restraining frame was a 14
inch.times.14 inch frame with pins around the periphery of the
frame, spaced with 1/2 inch separation between pins. The
restraining action of the pins prevented the nonwoven fabric from
shrinking when heated. The conditioning at elevated temperature
causes stress relaxation in the fibers.
[0167] This fabric exhibited very good fiber entanglement with no
loose fibers on the surface. The fabric exhibited good smooth
surface texture.
Example 9
[0168] The fabric of Example 6 was heat set by placing pieces of
nonwoven fabric on a restraining frame and conditioning the
nonwoven fabric in a forced air oven at 130.degree. C. for 5
minutes conditioning time. The restraining frame was a 14
inch.times.14 inch frame with pins around the periphery of the
frame, spaced with 1/2 inch separation between pins. The
restraining action of the pins prevented the nonwoven fabric from
shrinking when heated. The conditioning at elevated temperature
causes stress relaxation in the fibers.
[0169] This fabric exhibited very good fiber entanglement with no
loose fibers on the surface. This fabric exhibited good smooth
surface texture.
Example 10
[0170] The nonwoven fabric of Example 7 was heat set by placing
pieces of nonwoven fabric on a restraining frame and conditioning
the nonwoven fabric in a forced air oven at 130.degree. C. for 5
minutes conditioning time. The restraining frame was a 14
inch.times.14 inch frame with pins around the periphery of the
frame, spaced with 1/2 inch separation between pins. The
restraining action of the pins prevented the nonwoven fabric from
shrinking when heated. The conditioning at elevated temperature
causes stress relaxation in the fibers.
[0171] This fabric exhibited very good fiber entanglement with no
loose fibers on the surface. This fabric exhibited good smooth
surface texture.
Comparative Example 1
[0172] The fabric of Example 1 was hydroentangled with high
velocity water jets using the hydroentangling unit described
previously. During the hydroentangling process the fabric passed
through the machine at a 10 meters/min. speed where the nonwoven
web was exposed to four high pressure hydroentangling jets
operating with jet pressures of 100 bar, 150 bar, 200 bar, and 200
bar respectively. The first two jets were applied to the fabric as
it was transferred on a 103 mesh screen belt to apply a fine mesh
pattern to the fabric. The third and fourth hydroentangling jets
were applied to the opposite side of the web as it was supported on
a hydroentangling drum operating under vacuum.
[0173] In the final step of the hydroentangling process the wet
fabric was passed through a drum dryer where 70.degree. C. air
passed through the fabric by the action of vacuum maintained within
the 1.4 meter diameter drum. In the process the fabric was only
partly dried when heated in the oven and exited in the wet state.
The residence time of the fabric in the oven was measured to be
about 18 seconds. As the fabric was wound onto a core some excess
water was squeezed out and it was noted that the water was cloudy
indicating some emulsification of sulfopolyester.
[0174] The fabric formed by this hydroentangling step was rinsed in
both in deionized water at 45.degree. C. and in a home washing
machine using a hot water (48.degree. C.) cycle. The fabric had a
highly wrinkled appearance with a large number of loose fibers on
the surface. The fabric was very "tacky" or "clingy" due to the
loose nature of the surface fibers in the fabric and not desirable
for textile applications.
Comparative Example 2
[0175] The nonwoven fabric of Comparative Example 1 was heat set by
placing pieces of fabric on a restraining frame and conditioning
the nonwoven fabric in a forced air oven at 130.degree. C. for 5
minutes conditioning time. The restraining frame was a 14
inch.times.14 inch frame with pins around the periphery of the
frame, spaced with 1/2 inch separation between pins. The
restraining action of the pins prevented the nonwoven fabric from
shrinking when heated. The conditioning at elevated temperature
causes stress relaxation in the fibers.
[0176] This fabric exhibited loose fibers on the surface and had
"tacky" or "clingy" feel due the excessive amount of loose fibers
on the surface.
* * * * *