U.S. patent application number 09/738289 was filed with the patent office on 2002-02-14 for treatment of polyamide with gas phase of acid, anhydride or amine.
This patent application is currently assigned to BASF Corporation. Invention is credited to Brank, Scott R., Hu, Harry Y., Ilg, Otto M..
Application Number | 20020019513 09/738289 |
Document ID | / |
Family ID | 24455631 |
Filed Date | 2002-02-14 |
United States Patent
Application |
20020019513 |
Kind Code |
A1 |
Ilg, Otto M. ; et
al. |
February 14, 2002 |
Treatment of polyamide with gas phase of acid, anhydride or
amine
Abstract
The end group content of polyamide in the solid state may be
reduced by treating the polyamide with gas-phase acid, anhydride,
or amine. Stain- or dye-resistant polyamide fibers can be made by
reducing the number of amino end groups. Reduction in the number of
carboxylic end groups reduces the rate of regeneration of starting
monomers during extrusion.
Inventors: |
Ilg, Otto M.; (Asheville,
NC) ; Hu, Harry Y.; (Arden, NC) ; Brank, Scott
R.; (Weaverville, NC) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201-4714
US
|
Assignee: |
BASF Corporation
|
Family ID: |
24455631 |
Appl. No.: |
09/738289 |
Filed: |
December 18, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09738289 |
Dec 18, 2000 |
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09613042 |
Jul 10, 2000 |
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6268468 |
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Current U.S.
Class: |
528/491 |
Current CPC
Class: |
Y10T 428/2913 20150115;
D01F 6/60 20130101; Y10T 428/2969 20150115; Y10T 428/2971 20150115;
D06M 13/203 20130101; C08G 69/48 20130101; D06M 23/06 20130101;
C08G 69/46 20130101; D06M 13/325 20130101; D06M 13/332 20130101;
D06M 13/188 20130101 |
Class at
Publication: |
528/491 |
International
Class: |
C08J 003/00 |
Claims
What is claimed is:
1. A method of processing solid-state polyamide comprising treating
said polyamide with gas-phase acid, anhydride, or amine.
2. The method of claim 1, wherein the acid is selected from the
group consisting of acetic acid, formic acid, and propionic
acid.
3. The method of claim 2, wherein the acid is acetic acid.
4. The method of claim 2, wherein the acid is formic acid.
5. The method of claim 1, wherein the anhydride is selected from
the group consisting of acetic anhydride, propionic anhydride, and
maleic anhydride.
6. The method of claim 5, wherein the anhydride is acetic
anhydride.
7. The method of claim 1, wherein the amine is selected from the
group consisting of ammonia; methyl amine; dimethyl amine; ethyl
amine; propylamine; 2-propylamine; butylamine; sec-butylamine;
tert-butylamine; pentylamine; 2-pentylamine; 3-pentylamine;
hexylamine; 2-hexylamine; 3-hexylamine, heptylamine; 2-heptylamine;
3-heptylamine; 4-heptylamine; octylamine; 2-octylamine;
3-octylamine; cyclopropylamine; cyclobutylamine; cyclohexylamine;
cycloheptylamine; cyclooctylamine; 1,1,3,3-tetramethylbutylamine;
diethylamine; diproylamine;dibytylamine;di- -sec-butylamine;
dipetylamine; N-ethylmethylamine; N-ethylpropylamine;
N-ethylpropylamine; 1,2-diaminopropane; 1,3-diaminopropane;
1,2-diaminobutane; 1,3-diaminobutane; and 1,4-diaminobutane.
8. The method of claim 7, wherein the amine is ammonia.
9. The method of claim 1, wherein the polyamide is treated with an
inert carrier gas containing the acid, anhydride, or amine.
10. The method of claim 9, wherein the carrier gas is nitrogen or
argon.
11. A method of reducing the amino end group content of polyamide
comprising treating said polyamide with gas-phase acid or
anhydride.
12. The method of claim 11, wherein the acid is selected from the
group consisting of acetic acid, formic acid, and propionic
acid.
13. The method of claim 12, wherein the acid is acetic acid.
14. The method of claim 12, wherein the acid is formic acid.
15. The method of claim 11, wherein the anhydride is selected from
the group consisting of acetic anhydride, propionic anhydride, and
maleic anhydride.
16. The method of claim 12, wherein the anhydride is acetic
anhydride.
17. A method of reducing the carboxylic end group content of
polyamide comprising treating said polyamide with gas-phase
amine.
18. The method of claim 17, wherein the amine is selected from the
group consisting of ammonia; methyl amine; dimethyl amine; ethyl
amine; propylamine; 2-propylamine; butylamine; sec-butylamine;
tert-butylamine; pentylamine; 2-pentylamine; 3-pentylamine;
hexylamine; 2-hexylamine; 3-hexylamine, heptylamine; 2-heptylamine;
3-heptylamine; 4-heptylamine; octylamine; 2-octylamine;
3-octylamine; cyclopropylamine; cyclobutylamine; cyclohexylamine;
cycloheptylamine; cyclooctylamine; 1,1,3,3-tetramethylbutylamine;
diethylamine; diproylamine;dibytylamine;di- -sec-butylamine;
dipetylamine; N-ethylmethylamine; N-ethylpropylamine;
N-ethylpropylamine; 1,2-diaminopropane; 1,3-diaminopropane;
1,2-diaminobutane; 1,3-diaminobutane; 1,4-diaminobutane
19. The method of claim 18, wherein the amine is ammonia.
20. A method of processing solid-state polyamide comprising
bringing said polyamide into contact with a gas-phase acid,
anhydride or amine for a time sufficient to reduce monomer
regeneration rate of the polyamide.
21. A fiber formed from a polyamide having reduced end group
content, wherein the end group content is reduced by treating the
polyamide in the solid state with the gas phase of acid, anhydride,
or amine.
22. A stain- or dye-resistant polyamide carpet fiber comprising a
polyamide having reduced end group content, wherein the end group
content is reduced by treating the polyamide in the solid state
with the gas phase of acid, anhydride, or amine.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to making stain- or
dye-resistant polyamide carpet fibers by reducing the amino end
group content of the polyamide. The present invention also relates
to reducing the rate of monomer regeneration during extrusion of
the polyamide by reducing the amount of end groups in the
polyamide.
BACKGROUND OF THE INVENTION
[0002] As used herein, the term "fiber" includes fibers of extreme
or indefinite length (ie., filaments) and fibers of short length
(i.e., staple fibers). The term "yarn" as used herein means a
continuous strand of fibers.
[0003] The terms "stain" and "staining" as used herein with
reference to polyamide fibers mean discoloration of such fibers
caused by a chemical or physical attraction thereof with a
substance such as, for example, food red. The terms
"stain-resistant" and "stain resistance" as used herein with
respect to polyamide fibers or carpets refers to the ability of the
fiber or carpet to resist staining.
[0004] As used herein, "unmodified polyamide" refers to a typical
commercially available polyamide with an AEG above 20 meq/kg that
is known in the art such as, for example, nylon 6 or nylon 6,6.
[0005] Polyamide fibers are relatively inexpensive and offer a
desirable combination of qualities such as durability, comfort, and
ease of manufacture into a broad range of colors, patterns, and
textures. As a result, polyamide fibers are widely used in the home
and industry as carpets, drapery material, upholstery, and
clothing. Carpets made from polyamide fibers are a popular floor
covering for residential and commercial applications.
[0006] Polyamide fibers dye easily with acid dyes. Consequently,
carpets made from polyamide fibers stain easily when exposed to
natural or artificial acid dyes that exist in some foods, drinks,
medicines, and other consumer products. The resulting stains cannot
be easily removed under ordinary cleaning conditions. The severe
staining of carpeting is a major problem for consumers. In fact,
surveys show that more carpets are replaced because of staining
than because of wear. Accordingly, it is desirable to provide
polyamide fibers that resist common household stains, thereby
increasing the life of the carpet.
[0007] One way of avoiding such staining is to topically apply to
the surface of the polyamide filaments materials that function as
stain blockers so as to prevent acid stains from permanently
coloring the yarn. Topical treatments may be sulfonated materials
that act as "colorless dyes" and bind the amine dye sites on the
polyamide polymer. Sulfonated products for topical application to
polyamide substrates are described in, for example, U.S. Pat. No.
4,963,409 to Liss et al., U.S. Pat. No. 5,223,340 to Moss, III et
al., U.S. Pat. No. 5,316,850 to Sargent et al., and U.S. Pat. No.
5,436,049 to Hu. Topical treatments, however, tend to be costly and
non-permanent (wash away with one or more shampoos).
[0008] Another way to make stain- or dye-resistant polyamide carpet
fibers is to reduce the number of amino end groups in the polyamide
yarn. Methods have been developed to reduce the amino end group
content of polyamide fibers by adding amino end group blockers such
as caprolactone and butyrolactone to the extruder during polymer
extrusion. Blocking the end groups during polymer production
greatly reduces the rate of polymerization, and the obtainable
amino end group level would still be too high to provide meaningful
stain resistance.
[0009] There remains a need for stain- or dye-resistant polyamide
carpet fibers that overcome the above-discussed limitations, as
well as a simpler and more economical process for producing the
same.
[0010] Moreover, during extrusion, polyamides regenerate the
starting monomers via the end groups in the melt. The regenerated
monomers are deposited on the extruder die, which causes fuming and
other processing problems. The regenerated monomers also show up in
the finished products.
[0011] A need exists, therefore, for a method of reducing the rate
of regeneration of starting monomers from polyamides during
extrusion.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide stain-
or dye-resistant polyamide carpet fibers.
[0013] It is also an object of the present invention to produce a
polyamide polymer that significantly slows down the rate of monomer
regeneration during extrusion or remelting.
[0014] It has now been found that these objects may be achieved by
reducing the number of end groups of solid state polyamide with an
acid, anhydride, or amine gas.
[0015] The above and other objects, effects, features, and
advantages of the present invention will become more apparent from
the following detailed description of the preferred embodiments
thereof.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] To promote an understanding of the principles of the present
invention, descriptions of specific embodiments of the invention
follow, and specific language is used to describe the same. It will
nevertheless be understood that no limitation of the scope of the
invention is intended by the use of this specific language and that
alterations, modifications, equivalents, and further applications
of the principles of the invention discussed are contemplated as
would normally occur to one of ordinary skill in the art to which
the invention pertains.
[0017] According to the present invention there is provided a
method of processing solid-state polyamide comprising treating said
polyamide with gas-phase acid, anhydride, or amine.
[0018] According to the present invention there is also provided a
method of reducing the amino end group content of polyamide
comprising treating said polyamide with gas-phase acid or
anhydride. The polyamide treated in accordance with the present
invention is particularly advantageous for solution-dyed fibers,
greatly reducing the staining propensity of such carpets.
[0019] To reduce the number of amino end groups, solid state
polyamide may be treated with an inert carrier gas such as nitrogen
or argon containing acid or anhydride at temperatures above the
boiling point of the acid or anhydride. The polyamide reacts in the
solid state with the acid or anhydride in the gas phase at
temperatures elevated above room temperature to reduce the number
of amino end groups in the polyamide. Suitable acids include acetic
acid, formic acid, and propionic acid. Acetic acid and formic acid
are the preferred acids. Suitable anhydrides include acetic
anhydride, maleic anhydride, and propionic anhydride. Acetic
anhydride is the preferred anhydride.
[0020] Further according to the present invention there is provided
a method of reducing the carboxylic end group content of polyamide
comprising treating said polyamide with gas-phase amine. Reducing
the carboxylic end group content reduces both the rate of monomer
regeneration during extrusion and the amount of regenerated
monomers in the finished products.
[0021] To reduce the number of carboxylic end groups, solid state
polyamide may be treated with amines that are in the gas phase.
More particularly, the polyamide is treated with a gas phase amine
at temperatures above its boiling point such that the amine reacts
with the polyamide to reduce the number of carboxylic end groups in
the polyamide. Suitable amines include ammonia; methyl amine;
dimethyl amine; ethyl amine; propylamine; 2-propylamine;
butylamine; sec-butylamine; tert-butylamine; pentylamine;
2-pentylamine; 3-pentylamine; hexylamine; 2-hexylamine;
3-hexylamine, heptylamine; 2-heptylamine; 3-heptylamine;
4-heptylamine; octylamine; 2-octylamine; 3-octylamine;
cyclopropylamine; cyclobutylamine; cyclohexylamine;
cycloheptylamine; cyclooctylamine; 1,1,3,3-tetramethylbutylamine;
diethylamine; diproylamine; dibytylamine;di-sec-butylamine;
dipetylamine; N-ethylmethylamine; N-ethylpropylamine;
N-ethylpropylamine; 1,2-diaminopropane; 1,3-diaminopropane;
1,2-diaminobutane; 1,3-diaminobutane; and 1,4-diaminobutane.
Preferred amines are ammonia, methyl amine, and dimethyl amine.
[0022] Polyamides suitable for use in the invention are those that
are generically known by the term "nylon" and that are long chain
synthetic polymers containing amide (--CO--NH--) linkages along the
main polymer chain. Examples of such polyamides include
homopolyamides and copolyamides that are obtained by the
polymerization of lactam or aminocaprionic acid, as well as a
copolymerization product from mixtures of diamines and dicarboxylic
acids or lactams.
[0023] Typical polyamides include nylon 6
[poly(epsilon-caprolactam)], nylon 6/6 (polyhexamethylene
adipamide), nylon 6/9, nylon 6/10, nylon 6T, nylon 6/12, nylon 11,
nylon 12, nylon 4/6, and copolymers or mixtures thereof. Polyamides
can also be copolymers of nylon 6 or nylon 6/6 and a nylon salt
obtained by reacting a dicarboxylic acid component such as
terephthalic acid, isophthalic acid, adipic acid, or sebacic acid
with a diamine such as hexamethylene diamine, methaxylene diamine,
or 1,4-bisaminomethylcyclohexane. Preferred polyamides are nylon 6
and nylon 6/6. Nylon 6 is most preferred.
[0024] The polyamide treated according to the present invention may
be formed into various articles. Non-limiting examples of such
articles include fibers, yarns, textile fabrics, and the like.
[0025] Fibers may be formed by subjecting the modified polyamide of
the present invention to any conventional fiber-forming process
such as, for example, that disclosed in U.S. Pat. Nos. 4,983,448 to
Karageorgiou and 5,487,860 to Kent et al., both of which are
incorporated herein by reference.
[0026] Carpet may be made using conventional carpet-making
techniques such as weaving or tufting the fibers into a backing
material and binding the fibers to the backing with latex or other
adhesives. The carpet may be cut-pile, berber, unlevel loop, level
loop, or any other style according to the popular fashion. If
desired, the carpet may be in the form of carpet tiles, with or
without foam backing. By way of example, in the case of cut-pile
carpeting, the yarn is tufted into a primary backing and cut to
form cut-pile carpeting. The primary backing material may be woven
or nonwoven jute, nylon, polyester, polypropylene, etc. The
cut-pile carpeting is dyed to the desired shade. The primary
backing is then coated with a suitable latex material such as a
conventional styrene-butadiene ("SB") latex, vinylidene chloride
polymer, or vinyl chloride-vinylidene chloride copolymers. It is
common practice to use fillers such as calcium carbonate to reduce
latex costs. The final step is to apply a secondary carpet backing
to the latex-based adhesive. The secondary backing may be jute,
polypropylene, nylon, polyester, etc. The carpet may be foam backed
or not. The carpet of the present invention can be a variety of
pile weights, pile heights, and styles. There is not currently
believed to be any limitation on the carpet style.
[0027] Additionally, the fibers may be dyed or colored utilizing
conventional fiber-coloring techniques. For example, the fibers of
this invention may be subjected to an acid dye bath to achieve
desired fiber coloration. Alternatively, the polyamide may be
colored in the melt prior to fiber formation (i.e., solution dyed)
using conventional pigments for such purpose.
[0028] The invention will be further described by reference to the
following detailed examples. The examples are set forth by way of
illustration and are not intended to limit the scope of the
invention. All percentages are percentages by weight unless
otherwise noted. In the following examples, the test procedures
described below are used to measure the stated properties.
Amino End Group Content
[0029] The amino end group content is determined by dissolving
about 2.0 g of the polymer in about 60 ml of a phenol-methanol
mixture (68:32). This solution is titrated with about 0.20 normal
HCl at about 250.degree. C. by a potentiometric method, wherein the
endpoint is determined by a steep potential increase.
Carboxylic End Group Content
[0030] The carboxylic end group content is determined by dissolving
0.30 g of the polymer in about 40 ml of benzyl alcohol at
1800.degree. C. The solution is titrated with about 0.03 normal
t-butyl ammonium hydroxide at 800.degree. C. to about 1000.degree.
C. by a potentiometric method, wherein the endpoint is determined
by a steep potential increase.
EXAMPLE 1
[0031] About 22.0 grams of bright nylon chip (BS700F available from
BASF Corporation, Mount Olive, N.J.) having an amino end group
content of 36.5 meq/kg is placed in a reaction chamber. The
reaction chamber is immersed in a silicone oil bath at about
1650.degree. C. A preheated nitrogen gas containing acetic acid
vapor at about 1650.degree. C. enters the reaction chamber from the
bottom. The excess gas escapes from the top of the chamber into a
water trap. After about 16 hours of reaction, the chamber is purged
with pure nitrogen at about 1650.degree. C. for about 4 hours. The
content of amino end groups is 7.0 meq/kg.
EXAMPLE 2
[0032] About 22.0 grams of dull nylon chip (BS410F available from
BASF Corporation, Mount Olive, N.J.) having an amino end group
content of 29.7 meq/kg is placed in a reaction chamber. The
reaction chamber is immersed in a silicone oil bath at about
165.degree. C. A preheated nitrogen gas containing acetic acid
vapor at about 1650.degree. C. enters the reaction chamber from the
bottom. The excess gas escapes from the top of the chamber into a
water trap. After about 24 hours of reaction, the chamber is purged
with pure nitrogen at about 1650.degree. C. for about 4 hours. The
content of amino end groups is 6.4 meq/kg.
EXAMPLE 3
[0033] About 22.0 grams of cationic nylon chip (BS600C available
from BASF Corporation, Mount Olive, N.J.) having an amino end group
content of 11.5 meq/kg is placed in a reaction chamber. The
reaction chamber is immersed in a silicone oil bath at about
1650.degree. C. A preheated nitrogen gas containing acetic acid
vapor at about 1650.degree. C. enters the reaction chamber from the
bottom. The excess gas escapes from the top of the chamber into a
water trap. After about 24 hours of reaction, the chamber is purged
with pure nitrogen at about 1650.degree. C. for about 4 hours. The
content of amino end groups is 6.1 meq/kg.
EXAMPLE 4
[0034] About 22.0 grams of bright nylon chip (BS700F available from
BASF Corporation, Mount Olive, N.J.) having a carboxylic end group
content of 59.0 meq/kg is placed in a reaction chamber. The
reaction chamber is immersed in a silicone oil bath at about
1650.degree. C. A preheated ammonia gas at about 1650.degree. C.
enters the reaction chamber from the bottom. The excess gas escapes
from the top of the chamber into a water trap. After about 20 hours
of reaction, the chamber is purged with pure nitrogen at about
165.degree. C. for about 4 hours. The content of carboxylic end
groups is 40.0 meq/kg.
EXAMPLE 5
Spinning of Bright 830 Denier/64 Filament Yarn
[0035] The nylon-6 polymer is extruded at 255-270.degree. C.
through a spinneret with a trilobal cross-section. The extruded
filaments are quenched in air and taken up at speed of 300 m/min.
The yarns are drawn on a drawing machine at a draw ration of 3.0.
The chemical properties of polymers and yarns are summarized in the
table 1.
1TABLE 1 Chemical Properties of Polymers and Yarns Regular
AEG-Blocked BS700F BS700F* Polymer Yarn Polymer Yarn RV 2.75 2.70
2.74 2.45 AEG (meg/kg) 37.4 34.0 7.7 8.7 CEG (meg/kg) 58 53 68 62
Extractables (%) 0.86 1.07 0.78 0.93 Caprolactam (%) 0.26 0.34 0.23
0.20 *AEG-Blocked BS700F was prepared from a scale-up of Example
1.
EXAMPLE 6
Dyeing Carpet Yarns of Example 5 with Acid Dyes
[0036] Samples are dyed into Gray shade in beakers placed in an
Atlas Lauder-Ometer at a volume equal to 20 times the weight of the
sample. A stock solution is prepared using deionized water with
0.5% Irgasol SW (available from Ciba Specialty Chemicals,
Greensboro, N.C.), 0.5 grams per liter of trisodium phosphate, and
0.25 grams per liter of Versene.TM. (Ethylenediaminetetraacetic
acid, disolium salt; sequestering agent) from Millinckrodt
Specialty chemicals Co., 0.027% Tectilon.TM. Blue 4R from Ciba. The
dye bath pH is adjusted to 5.8 with acetic acid. Yarn samples in
beakers are heated to 95.degree. C. over 30 minutes and held at
95.degree. C. for 30 minutes. After the yarns are rinsed with warm
and cold water, the yarns are extracted and dried in a dryer.
(Tectilon.TM. dyes are commercially available from Ciba Specialty
Chemicals.)
EXAMPLE 7
Stain Test with C.I. Flood Red 17
[0037] A Sauer's Red Food Color (Color Index Food Red 17 or
FD&C Red 40) from C.F. Sauer Company is prepared at 2.5 grams
per liter concentration and adjusted to pH 2.8 with citric acid.
Knitted tube sample is paced in a 10 to 1 bath ratio of Food Red 17
for 5 minutes at room temperature. then the sample is removed from
the bath and squeezed slightly. After the sample is dried on
screens for at leas 16 hours, it is rinsed under running faucet of
cold water until no more than is removed. The sample is centrifuged
and tumble dried. The test results are listed in Table 2.
2TABLE 2 Comparison of AEG-Blocked Nylon with Regular Nylon in
Stain Test Discoloration (Delta E) Regular BS700F Yarn AEG-Blocked
BS700F Yarn Food Red-17 18.17 6.46
[0038] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalents
arrangements included within the spirit and scope of the appended
claims.
* * * * *