U.S. patent application number 10/505248 was filed with the patent office on 2005-09-15 for chemical compounds and methods for removing dye.
Invention is credited to Berard, Raymond A., Hensler, Connie D..
Application Number | 20050198742 10/505248 |
Document ID | / |
Family ID | 27663193 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050198742 |
Kind Code |
A1 |
Berard, Raymond A. ; et
al. |
September 15, 2005 |
Chemical compounds and methods for removing dye
Abstract
Chemical compounds and methods for removing dye from polyester
fibers, in particular poly(ethylene terephthalate) ("PET") fibers,
is disclosed. The compounds and methods are particularly useful for
removing dye from panel fabric made from recycled PET fibers. The
method involves contacting the PET with a dye removal compound in a
sealable vessel. The contents of the vessel are agitated and heated
to achieve an increase in pressure and temperature. Following a
cooling down period, the PET is removed and rinsed with water. The
dye removal compound includes an aqueous solution of at least one
leveling agent.
Inventors: |
Berard, Raymond A.;
(Portsmouth, RI) ; Hensler, Connie D.; (Kennesaw,
GA) |
Correspondence
Address: |
JOHN S. PRATT, ESQ
KILPATRICK STOCKTON, LLP
1100 PEACHTREE STREET
ATLANTA
GA
30309
US
|
Family ID: |
27663193 |
Appl. No.: |
10/505248 |
Filed: |
August 20, 2004 |
PCT Filed: |
January 31, 2003 |
PCT NO: |
PCT/US03/03046 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60353311 |
Feb 1, 2002 |
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Current U.S.
Class: |
8/115.51 |
Current CPC
Class: |
B29L 2031/731 20130101;
D06P 1/6498 20130101; C08J 11/06 20130101; Y02W 30/622 20150501;
B01F 17/0028 20130101; Y02W 30/701 20150501; C08J 2367/02 20130101;
B29K 2067/00 20130101; D06P 3/52 20130101; D06P 1/65131 20130101;
B29B 2017/0293 20130101; Y02W 30/62 20150501; B29B 17/02 20130101;
D06P 5/137 20130101; D06P 1/65118 20130101; D06P 1/6138
20130101 |
Class at
Publication: |
008/115.51 |
International
Class: |
D06M 010/00 |
Claims
What is claimed is:
1. A method for removing dye from polyester comprising: a)
contacting the polyester with a dye removal composition comprising
an aqueous solution of at least one leveling agent to form a
mixture; b) heating the mixture until it reaches an elevated
temperature and a pressure higher than the equilibrium pressure of
the dye removal composition at the elevated temperature; c)
maintaining the mixture at the elevated temperature and pressure
for a time interval sufficient to at least partially remove dye
from the polyester; d) cooling the mixture; e) separating the
polyester from the mixture; and f) removing any residual dye
removal composition from the polyester.
2. The method of claim 1 wherein the dye removal composition
further comprises at least one chemical selected from the group
consisting of scouring agents, wetting agents and leveling
carriers.
3. The method of claim 1 wherein the leveling agent is selected
from the group consisting of anionic leveling agents, nonionic
leveling agents and mixtures thereof.
4. The method of claim 3 wherein the leveling agent is selected
from the group consisting of alkyl polyglycol ether, isopropyl
alcohol, n-butyl phthalimide, nonyl phenol ethoxylate and
combinations thereof.
5. The method of claim 2 wherein the scouring agent or wetting
agent is nonionic.
6. The method of claim 5 wherein the nonionic scouring agent or
wetting agent is selected from the group consisting of
polyoxyethene ethers.
7. The method of claim 2 wherein the leveling carrier comprises a
nonionic leveling carrier.
8. The method of claim 7 wherein the nonionic leveling carrier
comprises alkyl phthalimide.
9. The method of claim 2 wherein the dye removal composition
comprises isopropyl alcohol, n-butyl phthalimide, nonyl phenol
ethoxylate, propylene glycol ether and combinations thereof.
10. The method of claim 1 wherein the dye removal composition
comprises an aqueous solution of about 0.5 wt % to about 8.0 wt %
of leveling agent, based on the total dye removal composition.
11. The method of claim 10 wherein the dye removal composition
comprises an aqueous solution of about 2.0 wt % to about 8.0 wt %/o
of leveling agent, based on the total dye removal composition.
12. The method of claim 11 wherein the dye removal composition
comprises an aqueous solution of about 4.0 wt % to about 8.0 wt %
leveling agent, based on the total dye removal composition.
13. The method of claim 1 wherein the mixture is agitated for about
120 minutes during one or more of the contacting, heating or
maintaining steps.
14. The method of claim 1 wherein the mixture is maintained at a
pressure of about 28 psi to about 39 psi.
15. The method of claim 14 wherein the mixture is maintained at a
pressure of about 33 psi.
16. The method of claim 1 wherein the mixture is heated to a
temperature of from about 135.degree. C. to about 145.degree.
C.
17. The method of claim 16 wherein the mixture is maintained at the
elevated temperature about 140.degree. C.
18. The method of claim 1 wherein the mixture is maintained at the
elevated temperature for a period of about 30 minutes to about 60
minutes.
19. The method of claim 18 wherein the mixture is maintained at the
elevated temperature for about 45 minutes.
20. The method of claim 1 wherein the mixture is cooled over a
period of about 20 minutes to about 40 minutes.
21. The method of claim 1 wherein the mixture is cooled to a
temperature of about 20.degree. C. to about 50.degree. C.
22. The method of claim 21 wherein the mixture is cooled to a
temperature of about 30.degree. C.
23. The method of claim 1 wherein the polyester comprises polyester
obtained from panel fabric.
24. The method of claim 23 wherein the panel fabric has been
garnetted into loose fibers.
25. The method of claim 1 wherein the method is carried out in a
sealable vessel.
26. The method of claim 1 wherein the method is carried out as a
batch process.
27. The method of claim 1 wherein the polyester comprises
poly(ethylene terephthalate) ("PET").
28. A method for removing dye from PET comprising: a) contacting
the PET with a dye removal composition comprising an aqueous
solution of one or more of propylene glycol ether, isopropyl
alcohol, n-butyl phthalimide and nonyl phenol ethoxylatein to form
a mixture; b) heating the mixture for about 120 minutes; c)
maintaining the temperature of the mixture at about 140.degree. C.
and the pressure at about 33 psi for a time sufficient to at least
partially remove dye from the PET; d) cooling the mixture to
30.degree. C. over a period of about 20 minutes to 40 minutes; e)
separating the PET from the mixture; and f) rinsing the PET with
water.
29. A composition for removing dye from polyester comprising an
aqueous solution of about 2.0 wt % to about 8.0 wt % of at least
one leveling agent, based on the total composition.
30. The composition of claim 29 wherein the composition comprises
an aqueous solution of about 4.0 wt % to about 8.0 wt % of leveling
agent, based on the total composition.
31. The composition of claim 29 further comprising at least one
chemical selected from the group consisting of scouring agents,
wetting agents and leveling carriers.
32. The composition of claim 29 further comprising at least one
leveling agent selected from the group consisting of anionic
leveling agents, nonionic leveling agents and mixtures thereof.
33. The composition of claim 32 wherein the leveling agent is
selected from the group consisting of alkyl polyglycol ether,
isopropyl alcohol, n-butyl phthalimide and nonyl phenol
ethoxylate.
34. The composition of claim 31 wherein the scouring agent or
wetting agent is nonionic.
35. The composition of claim 34 wherein the nonionic scouring agent
or wetting agent is selected from the group consisting of
polyoxyethene ethers.
36. The composition of claim 31 wherein the leveling carrier
comprises a nonionic leveling carrier.
37. The composition of claim 36 wherein the nonionic leveling
carrier comprises alkyl phthalimide.
38. The composition of claim 31 wherein the composition comprises
isopropyl alcohol, n-butyl phthalimide, nonyl phenol ethoxylate,
and propylene glycol ether.
39. The composition of claim 29 wherein the polyester comprises
PET.
40. A device for removing dye from polyester, comprising: a
sealable vessel; and a dye removal composition disposed therein,
the dye removal composition comprising an aqueous solution of about
2.0 wt % to about 8.0 wt % of at least one leveling agent, based on
the total dye removal composition.
41. The device of claim 40, wherein the dye removal composition
comprises an aqueous solution of about 4.0 wt % to about 8.0 wt %
leveling agent.
42. The device of claim 40 wherein the dye removal composition
further comprises at least one chemical selected from the group
consisting of scouring agents, wetting agents and leveling
carriers.
43. The device of claim 40 wherein the dye removal composition
comprises at least one leveling agent selected from the group
consisting of anionic leveling agents, nonionic leveling agents and
mixtures thereof.
44. The device of claim 43 wherein the dye removal composition
comprises at least one leveling agent selected from the group
consisting of alkyl polyglycol ether, isopropyl alcohol, n-butyl
phthalimide and nonyl phenol ethoxylate.
45. The device of claim 42 wherein the scouring agent or wetting
agent is nonionic.
46. The device of claim 45 wherein the nonionic scouring agent or
wetting agent is selected from the group consisting of
polyoxyethene ethers.
47. The device of claim 42 wherein the leveling carrier comprises a
nonionic leveling carrier.
48. The device of claim 47 wherein the nonionic leveling carrier
comprises alkyl phthalimide.
49. The device of claim 40 wherein the dye removal composition
comprises one or more of isopropyl alcohol, n-butyl phthalimide,
nonyl phenol ethoxylate and propylene glycol ether.
50. The device of claim 40 wherein the polyester comprises PET.
51. A method for recycling panel fabric comprising polyester, the
method comprising: a) removing from the fabric any structural
elements; b) removing dye from the fabric using the method of claim
1; c) recovering the polyester; d) melting the polyester; e)
pelletizing the melted polyester; and f) extruding the resulting
pellets into full-length fiber.
52. The method of claim 51 wherein the contacting takes place in a
sealable vessel and the residual dye removal composition is removed
by rinsing with water.
53. The method of claim 51 wherein the dye removal composition
further comprises at least one chemical selected from the group
consisting of scouring agents, wetting agents and leveling
carriers.
54. The method of claim 53 wherein the dye removal composition
comprises isopropyl alcohol, n-butyl phthalimide, nonyl phenol
ethoxylate, and propylene glycol ether.
55. The method of claim 51 wherein the polyester comprises PET.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to chemical compounds and methods for
removing dye from polyester fibers, and more particularly to
removing dye from panel fabric made from recycled poly(ethylene
terephthalate) fibers.
[0003] 2. Description of Related Art
[0004] Panel fabric, also known as vertical fabric, is used in
furniture upholstery, wall systems and tackboards. Panel fabric is
increasingly produced from synthetic materials such as polyester,
most commonly PET (poly(ethylene terephthalate)). Panel fabric is
replaced periodically and as a result, is often discarded in
landfills. Many of the materials used in panel fabric are not
biodegradable; thus disposal of it contributes to the environmental
problems that arise from the over-use of landfills.
[0005] Manufacturers of panel fabrics and other materials
incorporating PET are concerned about the effect of depletion of
petroleum (used to make the polymers in the fabric) and the
over-use of landfills on the environment. In an effort to reduce
the amount of non-biodegradable waste that finds its way into
landfills, some manufacturers use fiber made from recycled PET
(often from recycled PET bottles, such as 2-liter soft drink
bottles) in panel fabric. However, when the furniture incorporating
recycled or virgin panel fabric is discarded or refurbished, the
fabric may nevertheless end up in a landfill. Reducing the vast
amount of used panel fabric that is discarded annually as landfill
waste by finding other uses for such materials is therefore
advantageous.
[0006] However, merely finding other, lower valued uses for the PET
in the panel fabric does not alone provide environmental
sustainability. As the material is continually downgraded (i.e.,
used in increasingly less valuable ways), demand for PET for the
higher valued uses remains to be satisfied with either virgin PET,
or PET that has been recycled from other uses. Accordingly, it is
desirable to find a way to avoid downcycling the PET in panel
fabric, i.e., to reuse the PET in a way that is economically and
environmentally of the same value as the panel fabric itself.
Ideally, the PET in the panel fabric would be recycled into fiber
that can be reused, e.g., suitable for weaving into new panel
fabric. In this way, the material is not only rendered recyclable,
but recyclable in a sustainable fashion, decreasing the need for
virgin PET or PET recycled from bottles, which can then be put to
other uses.
[0007] Currently, when furniture incorporating panel fabric made
from recycled PET is discarded or refurbished, any PET that may be
recovered when garnetted into loose fibers is unsuitable for
significant reuse in panel fabric and carpet manufacturing. The
staple fiber is generally too short to be reused in the yarn
spinning process at more than about 3%. If the fibers could be
melted, pelletized and extruded into full-length fiber, they could
be recycled at about 100%. Unfortunately, the presence of dyes in
the fibers makes them difficult to melt and extrude. The dye
molecules char and burn at extrusion temperatures, forming a
residue that blocks the extrusion spinnerets. As a result, a
process capable of removing dye before extrusion is needed.
[0008] Existing processes may strip or decrease dye levels in
polyester, but they do so by breaking the chromophore of the dye.
Methods commonly used for color removal employ harsh chemicals like
sodium bisulfite, which hydrolyze or oxidize the dye, leaving the
decolorized dye in the fiber. This eliminates the color, but leaves
the remainder of the dye molecule in the fiber. Thus, when the
fiber is melted and extruded, the remaining molecule chars and
burns, blocking the extrusion spinnerets.
[0009] J. R. Aspland, Textile Dyeing and Coloration (American Ass'n
of Textile Chemists & Colorists 1997) describes the removal of
dye from a polyester fiber at room temperature using methylene
chloride. However, this solvent damages the polymer by swelling the
PET fiber and solvating the dye. The damage caused is partial
hydrolysis of the PET, which causes loss of strength and
brittleness in the fibers. For at least this reason, this method is
inappropriate for use in manufacturing new carpet or panel fabric.
There is therefore a need in the art for a dye removal process that
does not damage PET, but effectively removes dye from it.
SUMMARY OF THE INVENTION
[0010] The invention solves some or all of the above mentioned
problems by providing methods and compositions for removing dye
molecules from polyester, PET in particular. The invention allows
the PET to be reused by pelletizing and extruding it into fiber
suitable for panel fabric or other applications calling for virgin
PET, without disrupting the extrusion process by dye molecule
charring.
[0011] The invention addresses the problem of downcycling the PET
in panel fabric by providing a way to use recycled PET that is
economically and environmentally of the same value as the panel
fabric itself. By using the method of the invention, the PET can be
melted, extruded and reused as panel fabric. The invention is an
improvement over existing processes because it completely removes
the dye molecules from the PET, instead of breaking only the
chromophore of the dye. Thus, when the method of the present
invention is used, the PET may be melted and extruded, without
remaining dye molecules burning or blocking the extrusion
spinnerets. Furthermore, the method of the present invention does
not damage the PET by swelling.
[0012] According to one embodiment of the invention, a method is
provided for removing dye from polyester fiber or fabric by
contacting the polyester with a dye removal composition containing
an aqueous solution of at least one leveling agent; heating the
mixture of polyester and dye removal composition until it reaches
an elevated temperature and pressure level higher than the
equilibrium pressure of the dye removal composition at the elevated
temperature; cooling the mixture; and removing the decolorized
polyester from the mixture.
[0013] According to another embodiment of the invention, a
composition for removing dye from polyester is provided. The
composition includes an aqueous solution of about 0.5 wt % to about
8.0 wt % of at least one leveling agent.
[0014] In another embodiment, the invention relates to a device for
removing dye from polyester according to the present invention. The
device includes a sealable vessel and a dye removal composition.
The dye removal composition includes an aqueous solution of about
0.5 wt % to about 8.0 wt % of at least one leveling agent.
[0015] The invention is also directed to a method for recycling
panel fabric comprising polyester. The method involves removing
from the fabric any structural elements, removing the dye from the
fabric using a dye removal composition comprising an aqueous
solution of at least one leveling agent, recovering the polyester
fibers, melting the fibers, pelletizing the melted fiber and
extruding the pellets into full-length fiber.
[0016] In a particular embodiment of the invention, the dye removal
composition comprises at least one leveling agent selected from the
group consisting of anionic leveling agents, nonionic leveling
agents and mixtures thereof.
[0017] In another particular embodiment of the invention, the dye
removal composition further comprises at least one chemical
selected from the group consisting of scouring agents, wetting
agents and leveling carriers. Leveling agents may perform one or
more of these functions in addition to their function as leveling
agents.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0018] The invention provides for a method of removing dye
molecules from polyester fiber, and is particularly useful with PET
fiber. The polyester may be used in the process as woven fabric or,
alternatively, garnetted into loose fibers. The polyester is
contacted with a dye removal composition comprising an aqueous
solution of at least one leveling agent. This may be conveniently
done in a standard dyeing vessel commonly used for disperse dyeing
of polyester, which is sealable and temperature controlled.
[0019] Effective leveling agents have good wetting, emulsifying and
dispersing properties and will prevent redeposition. A leveling
agent that promotes maximum coverage and color yield is also
desirable. Leveling agents particularly suited for high temperature
polyester dyeing will generally be suitable for the present
invention. Effective leveling agents can also inhibit cationic dye
from staining and settling on the walls of stainless steel
equipments.
[0020] The dye removal composition comprises an aqueous solution of
at least one leveling agent. Suitable leveling agents include
anionic leveling agents, nonionic leveling agents and mixtures
thereof. The dye removal composition may further comprise leveling
carriers, scouring agents and mixtures thereof. In a particular
embodiment of the invention, the scouring agent or wetting agent is
nonionic. In another embodiment of the invention, the leveling
carrier comprises a nonionic leveling carrier.
[0021] More particularly, examples of suitable leveling agents
include those that comprise alkyl polyglycol ether, isopropyl
alcohol, n-butyl phthalimide or nonyl phenol ethoxylate. Examples
of suitable leveling carriers include those containing alkyl
phthalimide. Examples of suitable scouring agents include scouring
agents containing polyoxyethene ether or propylene glycol ether. In
a most preferred embodiment of the invention, the dye removal
composition comprises isopropyl alcohol, n-butyl phthalimide, nonyl
phenol ethoxylate, and propylene glycol ether.
[0022] Particular leveling agents that may be used for the present
invention include AVOLAN IW LIQUID.TM. nonionic leveling agent and
scouring agent (Bayer, Pittsburgh, Pa.), DIADAVIN UFN.TM. nonionic
leveling wetting and scouring agent (Bayer, Pittsburgh, Pa.),
LEVEGAL EAP-4.TM. leveling carrier (Bayer, Pittsburgh, Pa.),
RAYCAPOL TDA-33 scouring agent (Clariant, Chicago, Ill.), RAYCALEV
D.TM. (leveling agent), CAROLID NOL leveling agent (Bayer,
Pittsburgh, Pa.) and RICHLEV D leveling agent (Richchem, High
Point, N.C.), BURCO SOUR LFE-810.TM. scouring agent (Burlington
Chemical Co., Burlington, N.C.).
[0023] When mixed with water or aqueous solution, the leveling
agents can be used in weight ratios ranging from (under certain
conditions) about 0.5% to as high as about 8.0% of leveling
agent:water. However, particularly desirable results are achieved
when the leveling agent(s) is present in an amount ranging from
about 2.0 wt % to about 8.0 wt % of the total solution of leveling
agents. An approximately 4.0 wt % aqueous solution of leveling
agent(s) has been found to be particularly suitable for most
applications. More particularly, an approximately 4.0 wt % solution
comprising propylene glycol ether, isopropyl alcohol, n-butyl
phthalimide and nonyl phenol ethoxylate and water has been found to
be suitable for most applications.
[0024] According to this invention, the polyester to be decolorized
is separated from any structural elements and placed in a sealable
vessel. The polyester may be woven fabric or loose fibers. Water
and a dye removal composition comprising at least one leveling
agent are added to a vessel at a temperature of about 20.degree. C.
to about 25.degree. C. Those with skill in the art will understand
that any vessel made of a nonreactive material and sealable may be
used in place of a standard dyeing vessel.
[0025] The mixture of the polyester and dye removal composition are
heated for a period of about 120 minutes. Because the vessel is
sealed, as the temperature increases, there is a corresponding rise
in the pressure. Thus, the pressure is higher than the equilibrium
pressure of the dye removal composition at the elevated
temperature. When the pressure has reached about 28 psi to about 39
psi, more particularly about 33 psi, and the temperature has
reached about 135.degree. C. to about 145.degree. C., more
particularly 140.degree. C., the vessel is maintained at that
pressure and temperature for about 30 minutes to about 60 minutes,
more particularly about 45 minutes.
[0026] The vessel may be agitated during the period when the
polyester is first contacted with the dye removal composition, when
it is heated, during the holding period when the temperature and
pressure are maintained, or any combination of these three.
Agitation can be achieved, for example, by rolling the vessel or by
continuously pumping the dye removal composition through the
polyester.
[0027] The holding stage is typically followed by a cooling down
period of about 20 minutes to about 40 minutes wherein the
temperature is decreased to about 20.degree. C. to about 50.degree.
C., more particularly 30.degree. C. The mixture should be cooled
rapidly to prevent or limit reabsorption of the dye by the
polyester.
[0028] The times and temperatures may vary somewhat depending upon
the dyestuff and the leveling agent chosen, but will generally fall
within the above ranges for most commonly encountered dyes.
[0029] The decolorized polyester is then removed from the mixture.
Any residual dye removal composition should be removed from the
polyester, in order to further limit the chance of reabsorption.
This can often be achieved by rinsing thoroughly with water.
[0030] This cycle may be repeated as needed to remove additional
dye from the polyester fiber or fabric. Those with skill in the art
will recognize that more intense colors may require additional
cycles to sufficiently decolorize the polyester. The method may be
carried out as a batch, sequential batch semi-continuous or
continuous process.
[0031] The invention may be used to recycle panel fabric made from
polyester. The invention is also useful for recycling panel fabric
made from polyester that has already been recycled, such as
recycled PET. To recycle panel fabric, it should first be separated
from any structural elements. The fabric can be, but is not
required to be garnetted into loose fibers. In order to fully
recycle the panel fabric so that it can be used again as panel
fabric or some other product of similar economic and environmental
value, any dye should be removed using a dye removal composition
comprising an aqueous solution of at least one leveling agent. Once
the dye has been removed, the polyester fibers can be recovered.
The fibers can be melted and pelletized before being extruded into
full-length fiber. Panel fabric may be created by weaving the
recycled fiber.
[0032] The invention can be more clearly understood by reference to
the following examples, which are not intended to limit the scope
of the invention in any way.
EXAMPLE 1
[0033] The process was carried out in an Ahiba Polymat dyeing
machine in sealed vessels. Fifty (50) mL of water was added to an
empty vessel. Four (4.0) mL of each of the following chemicals were
also added to the vessel: CAROLID NOL.TM. leveling agent, BURCO
SCOUR LFE-810.TM. scouring agent, and RICHLEV D.TM. leveling agent.
Approximately 5.00 g of polyester was placed into the vessel. Fifty
(50) mL of water was added to the vessel to cover the polyester.
The vessel was sealed. The vessel was rolled to agitate the
mixture. The temperature was raised from room temperature (about
22.degree. C.) to 50.degree. C. The temperature was held at
50.degree. C. for 3.3 minutes. Next, the temperature was raised,
over 40 minutes, to 70.degree. C. at a gradient of 0.5. The
temperature was then raised to 140.degree. C. at a gradient of 1.5
over a period of 46.7 minutes. Finally, the temperature was
reduced, over 30.0 minutes, to 50.degree. C. at a gradient of 0.5.
The total running time was 116.7 minutes.
[0034] The process was carried out in an Ahiba Polymat dyeing
machine in sealed vessels. Fifty (50) mL of water was added to an
empty vessel. Four (4.0) mL of each of the following chemicals were
also added to the vessel: AVOLAN IW LIQUID.TM. leveling agent,
DIADAVIN UFN.TM. scouring agent, LEVEGAL EAP-4.TM. leveling carrier
and RAYCALEV D.TM. leveling agent. Approximately 5.00 g of
polyester was placed into the vessel. Fifty (50) mL of water was
added to the vessel to cover the polyester. The vessel was sealed.
The vessel was rolled to agitate the mixture. The temperature was
raised from room temperature (about 22.degree. C.) to 50.degree. C.
The temperature was held at 50.degree. C. for 3.3 minutes. Next,
the temperature was raised, over 40 minutes, to 70.degree. C. at a
gradient of 0.5. The temperature was then raised to 135.degree. C.
at a gradient of 1.5 over a period of 46.7 minutes. Finally, the
temperature was reduced, over 30.0 minutes, to 50.degree. C. at a
gradient of 0.5. The total running time was 116.7 minutes.
[0035] The foregoing description is provided for describing various
embodiments and structures relating to the invention. Various
modifications, additions and deletions may be made to these
embodiments and/or structures without departing from the scope and
spirit of the invention.
* * * * *