U.S. patent application number 13/466052 was filed with the patent office on 2012-08-30 for water stable fibers and articles comprising starch, and methods of making the same.
Invention is credited to William M. Allen, JR., James T. Knapmeyer, Isao Noda, Michael M. Satkowski.
Application Number | 20120216709 13/466052 |
Document ID | / |
Family ID | 37642071 |
Filed Date | 2012-08-30 |
United States Patent
Application |
20120216709 |
Kind Code |
A1 |
Noda; Isao ; et al. |
August 30, 2012 |
WATER STABLE FIBERS AND ARTICLES COMPRISING STARCH, AND METHODS OF
MAKING THE SAME
Abstract
Water stable fibers and articles made therefrom are formed from
a thermoplastic composition comprising destructured starch,
polyhydric alcohol, acid, and optionally triglyceride. Processes
for making water stable compositions may comprise melt extruding a
mixture of destructured starch, polyhydric alcohol, acid, and
optionally triglyceride, to form an extrudate, and heating the
mixture, extrudate, or both to provide a water stable article.
Inventors: |
Noda; Isao; (Fairfield,
OH) ; Satkowski; Michael M.; (Oxford, OH) ;
Allen, JR.; William M.; (Liberty Township, OH) ;
Knapmeyer; James T.; (Rossmoyne, OH) |
Family ID: |
37642071 |
Appl. No.: |
13/466052 |
Filed: |
May 7, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11545264 |
Oct 10, 2006 |
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13466052 |
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60725424 |
Oct 11, 2005 |
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Current U.S.
Class: |
106/209.1 ;
106/215.4; 524/47; 524/52; 524/53 |
Current CPC
Class: |
D21H 17/28 20130101;
D04H 1/54 20130101; A61L 15/28 20130101; D21H 27/10 20130101; C08L
23/12 20130101; C08L 91/00 20130101; D01F 8/06 20130101; Y10T
442/638 20150401; Y10T 442/641 20150401; D04H 1/4266 20130101; D01F
8/18 20130101; D04H 3/16 20130101; D01F 8/14 20130101; D04H 1/70
20130101; D21H 17/53 20130101; D21H 13/30 20130101; D21H 17/15
20130101; D01F 11/00 20130101; D01F 1/10 20130101; D04H 1/435
20130101; A61L 15/28 20130101; D21H 13/14 20130101; D21H 17/47
20130101; Y10T 442/637 20150401; D01F 6/90 20130101; C08L 2205/02
20130101; C08L 3/08 20130101; D01F 9/00 20130101; C08L 3/02
20130101; Y10T 428/2929 20150115; D21H 15/10 20130101; Y10T
428/2931 20150115; D21H 17/13 20130101; D21H 17/38 20130101; Y10T
442/642 20150401; C08L 3/08 20130101; C08L 3/04 20130101; D01F 6/46
20130101; A61L 15/28 20130101; D01F 6/92 20130101; D04H 1/4382
20130101; C08L 2666/02 20130101; C08L 3/02 20130101; C08L 2666/02
20130101; C08L 3/02 20130101; Y10T 442/696 20150401 |
Class at
Publication: |
106/209.1 ;
106/215.4; 524/53; 524/47; 524/52 |
International
Class: |
C08L 3/00 20060101
C08L003/00 |
Claims
1. A fiber comprising a thermoplastic starch composition, said
composition comprising: a. destructured starch; and b. ester
condensation products formed from a reactant mixture comprising: i.
polyhydric alcohol having alcohol functional groups; and ii. acid
with at least one functional group selected from the group
consisting of: carboxylic acid; carboxylic acid anhydride; and
combinations thereof; said functional groups being present in said
reactant mixture in a molar ratio of said alcohol functional groups
to said at least one acid functional group of from about 1:1 to
about 200:1; wherein said fiber is Water Stable.
2. The fiber of claim 1, said composition further comprising
transesterification products formed from a reactant mixture
comprising: polyhydric alcohol and triglyceride.
3. The fiber of claim 1, wherein said acid is selected from the
group consisting of: monoacid; diacid; polyacid; polymer comprising
at least one acid moiety; co-polymer comprising at least one acid
moiety; anhydrides thereof; and combinations thereof.
4. The fiber of claim 3, wherein said acid is selected from the
group consisting of: adipic acid; sebatic acid; lauric acid;
stearic acid; myristic acid; palmitic acid; oleic acid; linoleic
acid; sebacic acid; citric acid; oxalic acid; malonic acid;
succinic acid; glutaric acid; maleic acid; fumaric acid; phthalic
acid; isophthalic acid; terphthalic acid; acrylic acid; polyacrylic
acid; ethylene acrylic acid copolymers; methacrylic acid; itaconic
acid; glycidyl methacrylate; and combinations thereof.
5. The fiber of claim 3, wherein said acid is selected from the
group consisting of: maleic acid anhydride; phthalic acid
anhydride; succinic acid anhydride; and combinations thereof.
6. The fiber of claim 1, wherein said polyhydric alcohol is
selected from the group consisting of: glycerol; glycol; sugar;
sugar alcohol; and combinations thereof.
7. The fiber of claim 1, wherein said thermoplastic composition
further comprises additional polymer selected from the group
consisting of: polyhydroxyalkanoate; polyvinyl alcohol;
polyethylene; polypropylene; maleated polyethylene; maleated
polypropylene; polyethylene terephthalate; polylactic acid;
modified polypropylene; nylon; caprolactone; and combinations
thereof.
8. The fiber of claim 1, wherein said fiber is biodegradable.
9. The fiber of claim 8, wherein said thermoplastic composition
further comprises an additional polymer selected from the group
consisting of: polyvinyl alcohol; ester polycondensates;
aliphatic/aromatic polyesters; and combinations thereof.
10. The fiber of claim 9, wherein said polymers are selected from
the group consisting of: polybutylene succinate; polybutylene
succinate co-adipate; co-polyesters of butylene diol, adipic acid,
terephtalic acid, and combinations thereof; and combinations
thereof.
11. The fiber of claim 1, wherein said fiber is selected from the
group consisting of monocomponent fibers; multicomponent fibers;
multiconstituent fibers; and combinations thereof.
12. The fiber of claim 11, wherein said fiber is a multicomponent
fiber having a sheath and a core, said core comprising said
thermoplastic starch composition.
13. The fiber of claim 11, wherein said sheath comprises polymers
selected from the group consisting of: polyethylene terephthalate;
polyethylene; polypropylene; polyhydroxyalkanoate; polylactic acid;
polyester; and combinations thereof.
14. The fiber of claim 11, wherein said fiber is a multicomponent
fiber having an islands-in-the-sea configuration, wherein said
islands comprise said thermoplastic starch composition.
15. A nonwoven fabric comprising the fiber of claim 1.
16. A personal hygiene article comprising the fiber of claim 1.
17. An absorbent article comprising the fiber of claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application which claims
the benefit of U.S. application Ser. No. 11/545,264 filed Oct. 10,
2006; which claims the benefit of U.S. Provisional Application No.
60/725,424, filed 11 Oct. 2005.
FIELD OF THE INVENTION
[0002] The present invention relates to fibers made from
thermoplastic starch compositions, and articles made therefrom. The
fibers and articles are water stable, or may be rendered so. The
invention also relates to methods of making the fibers and
articles.
BACKGROUND OF THE INVENTION
[0003] There have been many attempts to make starch-containing
fibers, particularly on a high speed industrial level. However,
starch fibers can be much more difficult to produce than films,
blow-molded articles, and injection-molded articles containing
starch because the material and processing characteristics for
fibers are much more stringent. For example, local strain rates and
shear rates can be much greater in fiber production than in other
processes. Additionally, a homogeneous composition may be required
for fiber spinning. For spinning fine fibers, small defects, slight
inconsistencies, or non-homogeneity in the melt are typically not
acceptable for current, commercially viable processes.
[0004] In recent years, attempts have been made to process starch
on standard equipment and using existing technology known in the
plastic industry. Fibers comprising starch may be desired over
conventional plastics for a variety of reasons. Unpredictable
fluctuations in price and availability of petroleum and its
derivatives have created serious disruptions to the stable supply
of petroleum-based polymers used in making synthetic fibers, for
example, those based on polyolefins. Starch also has material
properties not typically provided by conventional polyolefin
plastics, including higher hydrophilicity (such as for improved
absorbency), as well as affinity and compatibility with other
materials not normally compatible with polyolefins. Starch may, in
some forms, also provide consumer-related benefits, like easy
disposability and/or flushability, and/or socially and
environmentally relevant properties, like bio-sourcing and
biodegradability. Starch may also provide a low-cost alternative to
conventional petroleum-based materials, for example
polypropylene.
[0005] In conventional processes, starch is typically combined with
one or more plasticizers or other process aids to render it
thermoplastic for processing, for example by melt spinning or other
melt extrusion techniques. Unfortunately, thermoplastic starch
(TPS) is highly susceptible to moisture. In fact, fibers made of
TPS can spontaneously pick up atmospheric moisture and become
tacky. When placed in water, TPS fibers from conventional starch
blends partially or fully disintegrate within hours. Although
methods exist for rendering thermoplastic compositions containing
starch more water stable including, but not limited the addition of
petroleum based polymers, there remains an unmet need for greater
water stability in such compositions and in articles made from such
compositions.
SUMMARY OF THE INVENTION
[0006] In some embodiments, the present invention relates to water
stable fibers which are made from thermoplastic polymer
compositions comprising destructured starch, and ester condensation
reaction products formed from a reaction mixture comprising
polyhydric alcohol and acid. In some embodiments, the water stable
fibers are made from thermoplastic polymer compositions comprising
destructured starch and reaction products of polyhydric alcohol and
a compound, wherein the reaction products are transesterification
reaction products, ester condensation reaction products, and
combinations thereof.
[0007] In some embodiments, the invention is directed to a method
of making water stable fibers. The method comprises the following
series of steps which may be completed in any suitable order. In
one step, a mixture of destructured starch, polyhydric alcohol,
acid, and optionally triglyceride, is formed. In a further step,
the mixture is extruded through a spinneret at an elevated
temperature to form fibers. In yet a further step, an ester
condensation reaction is induced between polyhydric alcohol and
acid and optionally a transesterification reaction is induced
between polyhydric alcohol and triglyceride.
[0008] In some embodiments, articles are made from the fibers of
the present invention. Non-limiting examples of articles in include
nonwovens. Specific embodiments include personal hygiene articles,
absorbent articles, and packaging.
[0009] In general, the present invention provides starch-based
compositions, fibers and articles in other forms with improved
water stability, and compositions and processes for making such
water stable compositions and articles. Water stability may be
achieved without requiring the use of petroleum based polymers
including, but not limited to, polyolefins. Water stability can
provide a variety of consumer-related benefits. The fibers,
compositions and processes may provide a low-cost alternative to
conventional petroleum-based materials. These and additional
advantages will be more apparent in view of the following detailed
description.
DETAILED DESCRIPTION
[0010] All percentages, ratios and proportions used herein are by
weight percent of the composition, unless otherwise specified. All
average values are calculated "by weight" of the composition or
components thereof, unless otherwise expressly indicated. "Average
molecular weight," or "molecular weight" for polymers, unless
otherwise indicated, refers to weight average molecular weight.
Weight average molecular weight, unless otherwise specified, is
determined by gel permeation chromatography.
[0011] "Copolymer" as used herein is meant to encompass copolymers,
terpolymers, and other multiple-monomer polymers.
[0012] "Reactant" as used herein refers to a chemical substance
that is present at the start of a chemical reaction.
[0013] "Mixture" as used herein refers to a mixture of two or more
of any of a defined group of components, unless otherwise
specified.
[0014] "Biodegradable" as used herein refers to the ability of a
compound to ultimately be degraded completely into CH.sub.4,
CO.sub.2 and water or biomass by microorganisms and/or natural
environmental factors.
[0015] "Fiber" as used herein includes staple fibers, fibers longer
than staple fibers that are not continuous, and continuous fibers,
which are sometimes referred to in the art as "substantially
continuous filaments" or simply "filaments". The method in which
the fiber is prepared will determine if the fiber is a staple fiber
or a continuous filament.
[0016] "Monocomponent fiber" as used herein, refers to a fiber
formed from using one or more extruders from only one polymer. This
is not meant to exclude fibers formed from one polymer to which
small amounts of additives have been added. Additives may be added
to the polymer for the purposes of providing the resulting fiber
with coloration, antistatic properties, lubrication,
hydrophilicity, and the like.
[0017] "Multicomponent fiber" as used herein refers to a fiber
formed from two or more different polymers that are extruded from
separate extruders and spun together to form one fiber.
[0018] "Bicomponent fibers" are one type of multicomponent fiber,
and are formed from two different polymers. Bicomponent fibers may
sometimes be referred to as "conjugate fibers" or "multicomponent
fibers". Bicomponent fibers may be comprised of polymers that are
substantially constantly positioned in distinct zones, both across
the cross-section of the bicomponent fibers and along their length.
Non-limiting examples of such bicomponent fibers include, but are
not limited to: sheath/core arrangements, wherein one polymer is
surrounded by another; side-by-side arrangements; segmented pie
arrangements; or even "islands-in-the-sea" arrangements. Each of
the aforementioned polymer arrangements is known in the art of
multicomponent (including bicomponent) fibers.
[0019] Bicomponent fibers can be splittable fibers; such fibers are
capable of being split lengthwise before or during processing into
multiple fibers with each of the multiple fibers having a smaller
cross-sectional dimension than that of the original bicomponent
fiber. Splittable fibers have been shown to produce softer nonwoven
webs due to their reduced cross-sectional dimensions.
Representative splittable fibers useful in the present invention
include type T-502 and T-512 16 segment PET/nylon 6, 2.5 denier
fibers, and type T-522 16 segment PET/PP splittable fibers, all of
which are available from Fiber Innovation Technology, Johnson City,
Tenn.
[0020] "Biconstituent fibers" as used herein, refers to fibers
which have been formed from at least two starting polymers extruded
as a blend from the same extruder. Biconstituent fibers may have
the various polymer components arranged in relatively constantly
positioned distinct zones across the cross-sectional area of the
fiber and the various polymers are usually not continuous along the
entire length of the fiber. In the alternative, biconstituent
fibers may comprise a blend, that may be homogeneous or otherwise,
of the at least two starting polymers. For example, a bicomponent
fiber may be formed from starting polymers which differ only in
molecular weight.
[0021] The polymers comprising biconstituent fibers may form
fibrils, which may begin and end at random along the length of the
fiber. Biconstituent fibers may sometimes be referred to as
multiconstituent fibers.
[0022] The terms "non-round fibers" and "shaped fibers" as used
interchangeably herein, refer to fibers having a cross-section that
is not circular, and includes, but is not limited to those fibers
that are "shaped fibers" and "capillary channel fibers." Such
fibers can be solid or hollow, and they can be tri-lobal,
delta-shaped, and are preferably fibers having capillary channels
on their outer surfaces. The capillary channels can be of various
cross-sectional shapes such as "U-shaped", "H-shaped", "C-shaped"
and "V-shaped". One preferred capillary channel fiber is T-401,
designated as 4DG fiber available from Fiber Innovation
Technologies, Johnson City, Tenn. T-401 fiber is a polyethylene
terephthalate (PET polyester). Further examples of shaped fibers of
use in the present invention are found in U.S. Pat. Pub. No.
2005/0176326 A1.
[0023] The terms "nonwoven web" or "web" are used interchangeably
herein, and refer to a layer of individual fibers or threads that
are interlaid, but not in an identifiable manner as in a knitted or
woven web. Nonwoven webs may be made via processes known in the
art, including those that comprise the following non-limiting
examples. Fiber laying processes of use may include, but are not
limited to: carding; airlaying; and wetlaying. Processes comprising
filament spinning from resin and integrated webforming include, but
are not limited to: spunbonding; meltblowing; coforming; and
forming spunbond-meltblown-spunbond composites. Fiber bonding
processes of use may include, but are not limited to: spunlacing
(i.e. hydroentanglement); cold calendering; hot calendering; air
thru bonding; chemical bonding; needle punching; and combinations
thereof.
[0024] "Compostable" as used herein refers to a material that meets
the following three requirements: (1) the material is capable of
being processed in a composting facility for solid waste; (2) if so
processed, the material will end up in the final compost; and (3)
if the compost is used in the soil, the material will ultimately
biodegrade in the soil.
[0025] "Comprising" as used herein means that various components,
ingredients or steps can be conjointly employed in practicing the
present invention. Accordingly, the term "comprising" encompasses
the more restrictive terms "consisting essentially of" and
"consisting of". The present compositions can comprise, consist
essentially of, or consist of any of the required and optional
elements disclosed herein.
[0026] Markush language as used herein encompasses combinations of
the individual Markush group members, unless otherwise
indicated.
[0027] All percentages, ratios and proportions used herein are by
weight percent of the composition, unless otherwise specified. All
average values are calculated "by weight" of the composition or
components thereof, unless otherwise expressly indicated.
[0028] All numerical ranges disclosed herein, are meant to
encompass each individual number within the range and to encompass
any combination of the disclosed upper and lower limits of the
ranges.
[0029] The present invention is directed to water stable fibers,
articles comprising water stable fibers, and processes for making
the same. Within the context of the present specification, "water
stable" describes a material that remains intact after two weeks in
200 ml of tap water at room temperature according to the following
procedure. 200 ml of tap water are charged to a clean glass
container, to which about 0.5 grams of material is added. The
material should be in a form that displays an aspect ratio of
greater than about 1:20 with a minimum axis no larger than 1 mm.
This condition is easily met for fibers of diameter less than 1 mm.
Suitably, at least 10 test pieces should be added to the container
with water. The container is closed and agitated by an orbital
mechanical shaker (for example a Madell Technology ZD-9556, Omaha
Nebr.) at 100 rpm for 15 minutes to coat the material with water.
After 1 hour, 24 hours, 48 hours, 72 hours and two weeks, the
contents are agitated by an orbital mechanical shaker at 100 rpm
for 15 minutes. If, after two weeks, the material is still intact,
with no disintegration, the material is considered to be water
stable. Suitably, each test piece remains a single entity with no
disintegration. The material may exhibit some swelling or other
dimensional change and still be water stable. In a specific
embodiment, the material does not exhibit a substantial decrease in
dimension when subjected to the described water stability test. The
term "substantial decrease in dimension" means that the average
maximum axis length of the tests pieces exhibits more than a 15%
decrease on average. In a more specific embodiment, the average
maximum axis length of the test pieces exhibits no more than a 10%
decrease on average. Averages are typically based on ten or more
test pieces.
[0030] The present fibers, articles comprising fibers, and
processes employ starch. In one embodiment, the invention is
directed to fibers made from a thermoplastic starch composition
comprising destructured starch, polyhydric alcohol, and acid and/or
triglyceride; the fibers may be rendered water stable by heating.
The thermoplastic polymer compositions of the present invention are
made from mixtures of materials also referred to herein as "starch
compositions".
[0031] Starch
[0032] Starch is naturally abundant and can be relatively
inexpensive. Thermoplastic starch can have desirable properties not
typically observed in conventional petroleum-based polymers
including, but not limited to, biodegradability, compostability,
natural hydrophilicity and compatibility with materials
traditionally incompatible with petroleum-based polymers.
[0033] Starch may take several different forms. As used herein,
"native starch" means starch as it is found in its naturally
occurring, unmodified form. Any suitable source of native starch is
of use in the present invention. Non-limiting examples of sources
include: corn starch, potato starch, sweet potato starch, wheat
starch, sago palm starch, tapioca starch, rice starch, soybean
starch, arrow root starch, bracken starch, lotus starch, cassaya
starch, waxy maize starch, high amylase corn starch, commercial
amylase powder, and combinations thereof.
[0034] Native starch generally has a granular structure. In order
to render starch capable of further processing, it is typically
subject to a destructuring process. Without wishing to be bound by
theory, it is believed that a starch granule is comprised of
discrete amylopectin and amylase regions. To convert native starch
to "destructured starch", the regions are broken apart during the
destructurization process, which is often followed by a volume
expansion of the starch, particularly in the presence of additives
including, but not limited to, plasticizer. The presence of a
plasticizer, such as polyhydric alcohol, when starch is
destructured typically increases the starch's viscosity as compared
to starch that is destructured in its absence. The destructuring
process is typically irreversible. In some embodiments of the
present invention, it may be desirable to destructure the starch as
fully as possible, so as to avoid "lumps" which may have an adverse
impact in subsequent processing steps including, but not limited to
fiber spinning processes.
[0035] Native starch of use in the present invention may be
destructured prior to its inclusion in the mixtures of present
invention. In addition, or in the alternative, native starch may be
destructured after it is in the mixture, i.e., in situ. In some
embodiments of the present invention, the use of native starch is
less expensive than using destructured starch, as it eliminates the
use of a separate, destructuring step.
[0036] Native starch may be destructured using any suitable means.
At least partial destructuring may be achieved through means
including, but not limited to: heating; enzyme modification;
chemical modification including but not limited to ethoxylation and
the like (such as by adding ethylene oxide for example); chemical
degradation; and combinations thereof. Agents that may act as
starch plasticizers may be used to destructure the starch. In some
embodiments, these agents may remain mixed with the starch during
further processing. In other embodiments, the agents may be
transient, meaning that they are removed so that they are not
present during further processing, and/or in the final fiber or
article comprising the fiber.
[0037] In some embodiments, destructured starch may encompass
native starch that has been destructured by modification, as
discussed above. Modified starch is defined as a native starch that
has had its native molecular characteristics (molecular weight or
chemical structure) altered in any way. For example, in some
embodiments, if the molecular weight of the native starch is
changed, but no other changes are made to the native starch, then
the starch can be referred to as a modified starch. Chemical
modifications of starch typically include acid or alkali hydrolysis
and oxidative chain scission to reduce molecular weight and
molecular weight distribution. Native starch generally has a very
high average molecular weight and a broad molecular weight
distribution (e.g. native corn starch has an average molecular
weight of up to about 60,000,000 grams/mole (g/mol)). The average
molecular weight of starch can be reduced as desired for the
present invention by acid reduction, oxidation reduction, enzymatic
reduction, hydrolysis (acid or alkaline catalyzed),
physical/mechanical degradation (e.g., via the thermomechanical
energy input of the processing equipment), and combinations
thereof. The thermomechanical method and the oxidation method offer
an additional advantage when carried out in situ. The exact
chemical nature of the starch and molecular weight reduction method
is not critical as long as the average molecular weight is in an
acceptable range. Ranges of weight average molecular weight for
starch or starch blends added to the melt can be from about 3,000
g/mol to about 8,000,000 g/mol, from about 10,000 g/mol to about
5,000,000 g/mol, or from about 20,000 g/mol to about 3,000,000
g/mol. In other embodiments, the average molecular weight is
otherwise within the above ranges but about 1,000,000 or less, or
about 700,000 or less. Starches having different molecular weights
may be mixed as desired for use in the invention.
[0038] In some embodiments, destructured starch encompasses
substituted starch. Substituted starches are starches that have
some of their alcohol (i.e., hydroxyl) functional groups replaced
by other chemical moieties. If substituted starch is desired,
chemical modifications of starch typically include etherification
and esterification. Chemical modification can be accomplished using
ethylene oxide, otherwise known as ethoxylation, resulting in
destructured starch as discussed above. Substituted starches may be
desired for better compatibility or miscibility with the
thermoplastic polymer and plasticizer. However, it may be desirable
to balance substitution with the reduction in the rate of
degradability. The degree of substitution of the chemically
substituted starch is typically from about 1% to about 100% (i.e.,
completely substituted). Alternatively, a low degree of
substitution, from about 1% to about 6%, may be used.
[0039] In some embodiments, the starch compositions or the
thermoplastic compositions of the present invention comprise from
about 1% to about 99%, from about 30% to about 90%, from about 50%
to about 85%, or from about 55% to 80% of starch, including the
bound water content of the starch. The starch is selected from the
group consisting of native starch, destructured starch (which may
include modified starch and/or substituted starch) and combinations
thereof. The term "bound water" refers to the water found naturally
occurring in starch before it is mixed with other components to
make the composition. In contrast, the term "free water" refers to
water that may be added to a composition of the present invention.
For example, free water may be incorporated as or with a
plasticizer. A person of ordinary skill in the art will recognize
that once the components are mixed in a composition, water can no
longer be distinguished by its origin. Starch that has not been
subjected to drying processes typically has bound water content
under ambient conditions of about 5% to about 16% by weight of
starch. In some embodiments of the present invention, the
compositions and articles of the invention comprise at least about
50% destructured starch, more specifically, at least about 60%
destructured starch.
[0040] Starch of use in the present invention may comprise any
combination of starches as described generally or specifically
herein, or as known in the art. Suitable starches of use may be
selected from the group consisting of: cold water insoluble starch;
cold water soluble starch; and combinations thereof. Wherein "cold
water" refers to water that is at or below 25.degree. C. As used
herein, cold water insoluble starch is starch that dissolves less
than 25% in water at 25.degree. C.
[0041] Thermoplastic starch used herein refers to a starch
composition that is capable of flowing when at an elevated
temperature (significantly above normal ambient temperature;
generally above 80.degree. C.), to the extent that the starch, or a
composition comprising the starch, can be adequately processed, for
example, for formation of homogeneous mixtures, spinning
performance and/or desired fiber properties. The fibers and/or
plastic articles comprising them are capable of solidifying after
the elevated temperature is lowered to ambient temperatures to
retain the shaped form.
[0042] Polyhydric Alcohol
[0043] "Polyhydric alcohol" as used herein refers to an alcohol
having two or more alcohol (i.e., hydroxyl) functional groups.
Without wishing to be bound by theory, it is believed (as mentioned
above) that polyhydric alcohol may act as a starch plasticizer in
the starch compositions of the present invention. In other words,
polyhydric alcohol is believed to enable the starch to flow and to
be processed, i.e., to create a thermoplastic starch.
[0044] Any suitable polyhydric alcohol or combination of polyhydric
alcohols is of use. Non-limiting examples of suitable polyhydric
alcohols include: glycerol (also known in the art as glycerin),
glycol, sugar, sugar alcohol, and combinations thereof.
Non-limiting examples of glycols of use include: ethylene glycol,
propylene glycol, dipropylene glycol, butylene glycol, hexane
triol, and the like, polymers thereof, and combinations thereof.
Non-limiting examples of sugars of use include: glucose, sucrose,
fructose, raffinose, maltodextrose, galactose, xylose, maltose,
lactose, mannose, erythrose, pentaerythritol, and mixtures thereof.
Non-limiting examples of sugar alcohols of use include: erythritol,
xylitol, malitol, mannitol, sorbitol, and mixtures thereof. In
specific embodiments of the present invention, the polyhydric
alcohol comprises glycerol, mannitol, sorbitol, and combinations
thereof.
[0045] In general, the polyhydric alcohol is substantially
compatible with the polymeric components with which it is
intermixed. As used herein, the term "substantially compatible"
means that when heated to a temperature above the softening and/or
the melting temperature of the composition, the polyhydric alcohol
is capable of forming a visually homogeneous mixture with polymer
present in the component in which it is intermixed. In some
embodiments, the plasticizer is water soluble.
[0046] In some embodiments of the present invention, the polyhydric
alcohol may also be used as a destructuring agent for starch. In
these embodiments, upon destructuring the starch, the polyhydric
alcohol may act as a plasticizer to the destructured starch,
thereby rendering it thermoplastic. In further embodiments, upon
destructuring the starch, the polyhydric alcohol may be removed and
substituted with a different plasticizer to render the destructured
starch thermoplastic. In some embodiments, the polyhydric alcohol
may improve the flexibility of the resulting fibers and/or plastic
articles comprising them.
[0047] Polyhydric alcohol is included in the present thermoplastic
compositions in any suitable amount for either destructuring starch
and/or rendering destructured starch thermoplastic. Generally, the
amount of polyhydric alcohol needed is dependent upon the molecular
weight of the starch, the amount of starch in the mixture, the
affinity of the polyhydric alcohol for the starch, and combinations
thereof. The polyhydric alcohol should sufficiently render the
starch component thermoplastic so that it can be processed
effectively, for example to form plastic articles. Generally, the
amount of polyhydric alcohol increases with increasing molecular
weight of starch. Typically, the polyhydric alcohol can be present
in compositions of the present invention in an amount of from about
2% to about 70%, from about 5% to about 50%, from about 10% to 30%,
or from about 15% to about 25%.
[0048] Acid
[0049] Acids of use in the present invention have at least one
functional group selected from the group consisting of: carboxylic
acid, carboxylic acid anhydride, and combinations thereof. Such
acids include, but are not limited to, monoacids, diacids,
polyacids (acids having at least three acid groups), polymers
comprising at least one acid moiety, co-polymers comprising at
least one acid moiety, anhydrides thereof, and mixtures
thereof.
[0050] Non-limiting examples of acids of use include: adipic acid,
sebatic acid, lauric acid, stearic acid, myristic acid, palmitic
acid, oleic acid, linoleic acid, sebacic acid, citric acid, oxalic
acid, malonic acid, succinic acid, glutaric acid, maleic acid,
fumaric acid, phthalic acid, isophthalic acid, terphthalic acid,
acrylic acid, methacrylic acid, itaconic acid, glycidyl
methacrylate, and combinations thereof. Anhydrides of such acids
may also be employed within the context of the present invention.
Non-limiting examples of acid anhydrides of use include: maleic
anhydride, phthalic anhydride, succinic anhydride and combinations
thereof.
[0051] Polymers and co-polymers comprising at least one acid
moiety, and/or their anhydrides are of use. Suitable polymers and
copolymers include, but are not limited to, those comprising
monomer units of acrylic acid, methacrylic acid, itaconic acid,
glycidyl methacrylate, anhydrides thereof, and combinations
thereof. The polymer can contain other monomer units in conjunction
with these acid monomer units. For example, ethylene-acid monomer
copolymers such as ethylene-acrylic acid copolymer can be used. In
a specific embodiment, the copolymers comprise at least 50 mol % of
acid monomer units. The molecular weight of such polymers and
copolymers can vary from as low as about 2,000 to over about
1,000,000. An example of a suitable polyacrylic acid is from
Aldrich Chemical Company, having a molecular weight of about
450,000. An example of a suitable ethylene-acrylic acid copolymer
is Primacore 59801 from Dow Chemical, having an acrylic acid
content of at least 50 mol %.
[0052] In specific embodiments, the acid comprises at least one
diacid, polyacid, acid polymer or copolymer, or a mixture thereof.
In other embodiments, the acid comprises a diacid, alone or in
combination with another acid, for example a monoacid. In further
embodiments, the acid comprises adipic acid, stearic acid, lauric
acid, citric acid, polyacrylic acid and/or ethylene-acrylic acid
copolymer.
[0053] Typically, the acid is employed in the starch composition in
an amount of from about 0.1% to about 30%, from about 1% to about
20%, or from about 2% to about 12%. In some embodiments, the molar
ratio of alcohol functional groups to acidic functional groups in
the starch composition is at least about 1:1, or at least about
4:1. In some embodiments, the molar ratio of alcohol functional
groups to acidic groups in the starch composition is from about 1:1
to about 200:1, or from about 1:1 to about 50:1.
[0054] Triglyceride
[0055] Any suitable triglycerides, which are also known in the art
as triacylglycerols, are of use in the present invention.
Non-limiting examples of triglycerides of use include: tristearin,
triolein, tripalmitin, 1,2-dipalmitoolein, 1,3-dipalmitoolein,
1-palmito-3-stearo-2-olein, 1-palmito-2-stearo-3-olein,
2-palmito-1-stearo-3-olein, trilinolein, 1,2-dipalmitolinolein,
1-palmito-dilinolein, 1-stearo-dilinolein, 1,2-diacetopalmitin,
1,2-distearo-olein, 1,3-distearo-olein, trimyristin, trilaurin and
combinations thereof.
[0056] Suitable triglycerides may be added to the present
compositions in neat form. Additionally, or alternatively, oils
and/or processed oils containing suitable triglycerides may be
added to the compositions. Non-limiting examples of oils include
coconut oil, corn germ oil, olive oil, palm seed oil, cottonseed
oil, palm oil, rapeseed oil, sunflower oil, whale oil, soybean oil,
peanut oil, linseed oil, tall oil, and combinations thereof.
[0057] Typically, triglycerides are employed in the starch
compositions in an amount of from about 0.1% to about 30%, from
about 1% to about 20%, or from about 2% to about 12%. In some
embodiments, the molar ratio of alcohol functional groups to ester
functional groups in the starch composition is at least about 1:1,
or at least about 4:1. In some embodiments, the molar ratio of
alcohol functional groups to ester functional groups in the starch
composition is from about 1:1 to about 200:1, or from about 1:1 to
about 50:1.
[0058] In some embodiments, combinations of acid and triglyceride
are employed in the starch compositions. In some embodiments, the
total amounts of acid and triglyceride is from about 0.1% to about
32%, from about 1% to about 25%, or from about 2% to about 20%.
Additionally, or alternatively, the molar ratio of the alcohol
functional groups to the total of ester and acid functional groups
is at least about 1:1, or at least about 4:1. In some embodiments,
the molar is from about 1:1 to about 200:1, or from about 1:1 to
about 50:1.
[0059] Additional Components
[0060] The compositions according to the present invention may
include one or more additional components as desired for the
processing and/or end use of the fibers and or plastic articles.
Additional components may be present in any suitable amount. In
some embodiments, additional components may be present in an amount
of from about 0.01% to about 35% or from about 2% to about 20%.
Non-limiting examples of additional components include, but are not
limited to, additional polymers, processing aids and the like.
[0061] Non-limiting examples of additional polymers of use include:
polyhydroxyalkanoates, polyvinyl alcohol, polyethylene,
polypropylene, polyethylene terephthalate, maleated polyethylene,
maleated polypropylene, polylactic acid, modified polypropylene,
nylon, caprolactone, and combinations thereof.
[0062] In embodiments in which properties including, but not
limited to, biodegradability and/or flushability are desired,
additional suitable biodegradable polymers and combinations of
thereof are of use. In some embodiments, polyesters containing
aliphatic components are suitable biodegradable thermoplastic
polymers. In some embodiments, among the polyesters, ester
polycondensates containing aliphatic constituents and
poly(hydroxycarboxylic) acid are preferred. The ester
polycondensates include, but are not limited to: diacids/diol
aliphatic polyesters such as polybutylene succinate, and
polybutylene succinate co-adipate; aliphatic/aromatic polyesters
such as terpolymers made of butylenes diol, adipic acid, and
terephtalic acid. The poly(hydroxycarboxylic) acids include, but
are not limited to: lactic acid based homopolymers and copolymers;
polyhydroxybutyrate; and other polyhydroxyalkanoate homopolymers
and copolymers. In some embodiments, a homopolymer or copolymer of
poly lactic acid is preferred. Modified polylactic acid and
different stereo configurations thereof may also be used. Suitable
polylactic acids typically have a molecular weight range of from
about 4,000 g/mol to about 400,000 g/mol. Examples of suitable
commercially available poly lactic acids include NATUREWORKS.TM.
from Cargill Dow and LACEA.TM. from Mitsui Chemical. An example of
a suitable commercially available diacid/diol aliphatic polyester
is the polybutylene succinate/adipate copolymers sold as
BIONOLLE.TM. 1000 and BIONOLLE.TM. 3000 from the Showa Highpolymer
Company, Ltd. Located in Tokyo, Japan. An example of a suitable
commercially available aliphatic/aromatic copolyester is the
poly(tetramethylene adipate-co-terephthalate) sold as EASTAR
BIO.TM. Copolyester from Eastman Chemical or ECOFLEX.TM. from BASF.
In some embodiments, the biodegradable polymer or combination of
polymers may comprise polyvinyl alcohol.
[0063] The aforementioned biodegradable polymers and combinations
thereof are present in an amount will be from about 0.1% to about
70%%, from about 1% to about 50%, or from about 2% to about 25%, by
weight of the present starch and thermoplastic starch
compositions.
[0064] Processing aids are generally present in the current
compositions in amounts of from about 0.1% to about 3%, or from
about 0.2% to about 2%. Non-limiting examples of processing aids
include: lubricants, anti-tack, polymers, surfactants, oils, slip
agents, and combinations thereof. Non-limiting examples of specific
processing aids include: Magnesium stearate; fatty acid amides;
metal salts of fatty acids; wax acid esters and their soaps; montan
wax acids, esters and their soaps; polyolefin waxes; non polar
polyolefin waxes; natural and synthetic paraffin waxes; fluoro
polymers; talc; silicon; clay; diatomaceous earth. Commercial
examples of such compounds include, but are not limited to:
Crodamide.TM. (Croda, North Humberside, UK), Atmer.TM. (Uniqema,
Everberg, Belgium,) and Epostan.TM. (Nippon Shokobai, Tokyo,
JP).
[0065] In some embodiments, the starch comprises at least about 50%
of all polymer components in the starch compositions, more
specifically at least about 60% of all polymer components in the
starch compositions.
[0066] Water Stability
[0067] Without wishing to be bound by theory, the thermoplastic
polymer compositions according to the present invention may be
rendered water stable via the aforementioned ester condensation
reaction and/or transesterification reaction. When the
thermoplastic polymer compositions are made into fibers and/or
articles comprising fibers, the reactions may be induced before
formation of the fiber and/or article, during formation of the
fiber and/or article, after the fiber's and/or article's formation
(i.e., curing) and combinations thereof. In some embodiments, the
reaction(s) are induced, and/or driven towards completion through
the application of heat. In some embodiments of the present
invention, a catalyst may be used to initiate and/or accelerate the
ester condensation and/or transesterification reactions. Any
suitable catalyst is of use. Non-limiting examples of useful
catalysts include Lewis acids. A non-limiting example of a Lewis
acid is para-toluene sulfonic acid.
[0068] With regard to the ester condensation reaction, it is
believed without being bound by theory that the heating of the
thermoplastic polymer composition comprising acid, may remove a
sufficient amount of water from the starch composition, (including
some, but not all of the bound water) to allow a reaction of the
polyhydric alcohol and the acid to form a water stable reaction
product to an extent that provides the resulting composition with
water stability. While again not wishing to be bound by theory, it
is believed that a condensation reaction may occur between the
polyhydric alcohol and acid. Generally, the chemistry which governs
such condensation reactions is known in the art as alkyd
chemistry.
[0069] In the present invention, it may be important that the ester
condensation reaction is not completed to such an extent that a gel
of the reaction products is formed before final processing of the
thermoplastic composition occurs. As used herein "gel" means a
material that is crosslinked to an extent that flow even under high
temperatures is no longer possible without degradation of the
material's molecular weight. It is important for the system to be
below the gel point of the reactants before final processing so as
to retain sufficient flow behavior to enable shaping the material
into films fibers or articles. The gel point is defined as the
state at which enough polymer chains formed by the products of the
reactants are bonded together such that at least one very large
molecule is coextensive with the polymer phase and flow is no
longer possible and the material behaves more like a solid.
[0070] Up until to the gel point, it may be advantageous for the
reaction to proceed to a point where prepolymers such as oligomers
or even larger molecules are formed, yet these species should
retain the ability to flow and be shaped into useful articles.
Oligomers as used herein are reaction products from constituent
monomers that include at least two monomers up to about ten
monomers. In some embodiments of the current invention, when
carrying out the ester condensation reaction between the acid and
alcohol and thereby forming oligomers, it may be advantageous to
remove excess water from the reaction product before forming the
end product. It is believed that removal of the water will speed
the ester condensation reaction toward completion in the final
processing step.
[0071] In some embodiments, the thermoplastic composition is heated
at a temperature of at least about 90.degree. C., more specifically
at least about 100.degree. C., to convert the thermoplastic
composition to a water stable composition. Typically, the
thermoplastic composition will not be heated at a temperature over
about 250.degree. C., or over about 225.degree. C. In some
embodiments, the thermoplastic composition is heated at a
temperature of at least about 115.degree. C. to convert the
thermoplastic composition to a water stable composition. In further
embodiments, the thermoplastic composition is heated at a
temperature of from about 130.degree. C. to about 180.degree. C. to
convert the thermoplastic composition to a water stable
composition. In some embodiments, the water content of the
composition is reduced to a level below the level of bound water
naturally present in the starch at ambient conditions. In other
embodiments, the water content of the composition is reduced to 5%
or less of the composition. In other embodiments, water content is
about 4% or less. In another embodiment the water content is
reduced to about 3% or less. In yet another embodiment, the water
content is reduced to about 2% or less. Water content can be
reduced by providing the starch composition at elevated
temperatures under conditions wherein water can vaporize.
[0072] Although not required, the physical form of the
thermoplastic polymer composition may be modified to provide a
greater surface area to facilitate water removal from the
compositions. The heating time necessary to convert a thermoplastic
composition to a water stable form will depend, in general, on a
variety of factors, including component compositions (i.e.,
particular starch, polyhydric alcohol and acid and/or
triglyceride), heating temperature, physical form of the
composition, and the like. Suitable times may range from
instantaneously to about 24 hours, about 1 minute to about 24
hours, from about 5 minutes to about 12 hours, or from about 5
minutes to about 1 hour. In general, water content should not be
reduced under conditions wherein decomposition, burning or
scorching of the starch occurs, particularly in the case that
visually noticeable or significant levels of decomposition, burning
or scorching occurs.
[0073] In some embodiments, the thermoplastic compositions
according to the present invention are formed by melt mixing and/or
extruding a mixture comprising destructured starch, polyhydric
alcohol, and acid and/or triglyceride, using conventional mixing
and/or extrusion techniques. The mixture may be formed by combining
destructured starch, polyhydric alcohol, and acid and/or
triglyceride. Alternatively, the mixture may be provided by
combining non-destructured starch, polyhydric alcohol, and acid
and/or triglyceride, with the additional step of destructuring the
starch in situ in the mixture, by any of the destructuring
techniques discussed above. The components are typically mixed
using conventional compounding techniques. The objective of the
compounding step is to produce at least a visually homogeneous melt
composition comprising the starch.
[0074] A suitable mixing device is a multiple mixing zone twin
screw extruder with multiple injection points. The multiple
injection points can be used to add the destructured starch,
polyhydric alcohol and acid and/or triglyceride. A twin screw batch
mixer or a single screw extrusion system can also be used. As long
as sufficient mixing and heating occurs, the particular equipment
used is not critical. An alternative method for compounding the
materials comprises adding the starch, polyhydric alcohol, and acid
and/or triglyceride to an extrusion system where they are mixed in
progressively increasing temperatures. For example, a twin screw
extruder with six heating zones may be employed. This procedure can
result in minimal thermal degradation of the starch and may ensure
that the starch is fully destructured. However, it may not be
necessary to extrude a melt mixture, and, in general, any method
known in the art or suitable for the purposes hereof can be used to
combine the ingredients of the components to form the thermoplastic
compositions of the present invention. Typically such techniques
will include heat and mixing, and optionally pressure. The
particular order or mixing, temperatures, mixing speeds or time,
and equipment can be varied, as will be understood by those skilled
in the art, however temperature should be controlled such that the
starch does not significantly degrade. Further, if the temperature
of the melt mixing and/or extrusion process is sufficiently high
and for a sufficient time to eliminate at least a portion of bound
water from the starch and drive a reaction between the polyhydric
alcohol and the acid, the thermoplastic composition which is formed
by melt extruding these components will convert to a water stable
composition. For example, the melt extrusion can be conducted in an
extruder provided with vents or other modifications which
facilitate water removal and the conversion to a water stable
composition. In such an embodiment, it is therefore advantageous to
melt extrude the composition to a form which is suitable for and
end use including, but not limited to, fibers or nonwovens
comprising the fibers.
[0075] On the other hand, if the temperature or conditions at which
the melt extrusion of the mixture comprising destructured starch,
polyhydric alcohol, acid and/or triglyceride is conducted at a
sufficiently low temperature and/or for an insufficient time to
eliminate at least a portion of bound water from the starch and
drive reaction between the polyhydric alcohol, acid and/or
triglyceride, the resulting extrudate comprises thermoplastic
compositions of the invention, which may be further processed, if
desired, and which are convertible to water stable compositions by
further heating. The extrudate can therefore be provided in this
embodiment in a form which facilitates handling, further
processing, or the like. For example, a thermoplastic composition
extrudate can be in pellet form, powder or crumb form or the like.
In a specific embodiment, the thermoplastic composition extrudate
is in a pellet form which is then suitable for melt extruding to a
desired end use form. In this embodiment, the further melt
extrusion of pellets (or extrudate of another form) to form fibers,
or articles comprising fibers, may be conducted under sufficient
conditions of temperature and time to effect the conversion of the
thermoplastic composition to a water stable composition or article.
Alternatively, if the melt extrusion is not conducted under
sufficient conditions of temperature and time to effect the
conversion of the thermoplastic composition to a water stable
composition, the resulting extrudate may be heated further to
effect the conversion of the extruded thermoplastic composition to
a water stable article.
[0076] In some embodiments, a thermoplastic composition in the form
of pellets is formed by melt extruding destructured starch,
polyhydric alcohol and acid and/or triglyceride. The extrusion
process may not provide sufficient heating of the thermoplastic
composition for a sufficient time to effect conversion to a water
stable composition. The pellets are subsequently subjected to melt
extrusion by conventional fiber spinning processes. The resulting
fibers are rendered water stable by an additional heating step at a
temperature of from about 100.degree. C., more specifically
115.degree. C., still more specifically from about 130.degree. C.,
to about 180.degree. C. Alternatively, the melt spinning process is
conducted at a temperature in this range under conditions by which
the resulting fibers are rendered water stable. In a further
embodiment, the necessary water is eliminated from the fibers by
flash evaporation as the fibers exit the spinneret swing to the
reduction in pressure.
[0077] In some embodiments, it may be advantageous to provide the
polyhydric alcohol and the acid and/or triglyceride as what is
termed herein as a "pre-polymer". In these instances, the
aforementioned condensation reaction and/or transesterification
reaction has already at least partially, but not completely, taken
place between the polyhydric alcohol and the acid and/or
triglyceride before it is mixed with the starch. In further
embodiments, the pre-polymer may also contain starch. Pre-polymers
may take any suitable form which may be convenient to make, ship
process and combinations thereof. Non-limiting examples of forms
include strands, pellets, powder, and combinations thereof.
[0078] In some embodiments, a thermoplastic composition in the form
of pellets is formed by melt extruding destructured starch,
polyhydric alcohol and acid and/or triglyceride. The extrusion
process does not provide sufficient heating of the thermoplastic
composition for a sufficient time to effect conversion to a water
stable composition. The pellets are subsequently subjected to melt
extrusion by conventional fiber spinning processes. The resulting
fibers are rendered water stable by an additional heating step at a
temperature of from about 100.degree. C., more specifically
115.degree. C., still more specifically from about 130.degree. C.,
to about 180.degree. C. Alternatively, the melt spinning process is
conducted at a temperature in this range under conditions by which
the resulting fibers are rendered water stable. In a further
embodiment, the necessary water is eliminated from the fibers by
flash evaporation as the fibers exit the spinneret and are subject
to a reduction in pressure.
[0079] In general, high fiber spinning rates are desired. Fiber
spinning speeds of about 10 meters/minute or greater can be used.
In some embodiments hereof, the fiber spinning speed is from about
100 to about 7,000 meters/minute, or from about 300 to about 3,000
meters/minute, or from about 500 to about 2,000 meters/minute. The
spun fibers can be collected using conventional godet winding
systems or through air drag attenuation devices. If the godet
system is used, the fibers can be further oriented through post
extrusion drawing as desired. The drawn fibers may then be crimped
and/or cut to form non-continuous fibers (staple fibers) used in a
carding, airlaid, or fluidlaid process. The fiber may be made by
fiber spinning processes using a high draw down ratio. The draw
down ratio is defined as the ratio of the fiber at its maximum
diameter (which is typically occurs immediately after exiting the
capillary of the spinneret in a conventional spinning process) to
the final diameter of the formed fiber. The fiber draw down ratio
via either staple, spunbond, or meltblown process will typically be
1.5 or greater, and can be about 5 or greater, about 10 or greater,
or about 12 or greater. Continuous fibers can be produced through,
for example, spunbond methods or meltblowing processes.
Alternately, non-continuous (staple fibers) fibers can be produced
according to conventional staple fiber processes as are well known
in the art. The various methods of fiber manufacturing can also be
combined to produce a combination technique, as will be understood
by those skilled in the art. Additionally, hollow core fibers as
disclosed in U.S. Pat. No. 6,368,990 can be formed.
[0080] Typically, the diameter of fibers produced according to the
present invention is less than about 200 microns, and in alternate
embodiments is less than about 100 microns, less than about 50
microns, or less than about 30 microns. In one embodiment, the
fibers have a diameter of from about 0.1 microns to about 25
microns. In another embodiment the fibers may have a diameter from
about 0.2 microns to about 15 microns. In other embodiment, the
fibers may have a diameter from about 5 microns to about 14
microns. Fiber diameter is controlled by factors well known in the
fiber spinning art including, for example, spinning speed and mass
through-put.
[0081] Fibers according to the present invention include, but are
not limited to, monocomponent fibers, multicomponent fibers (such
as bicomponent fibers), or biconstituent fibers. The fibers may
take any suitable shape including, round or non-round. Non-round
fibers include, but are not limited to those described above.
[0082] In some embodiments, the fiber is a multicomponent fiber
having a sheath and a core. Either the core or the sheath or both
the core and sheath may comprise a thermoplastic starch composition
according to the present invention. In embodiments, in which the
core is a thermoplastic composition according to the present
invention, the sheath comprises a different polymer. Non-limiting
examples of such polymers include those selected from the group
consisting of: polyethylene terephthalate; polyethylene;
polypropylene; polyhydroxyalkanoate; polylactic acid; polyester;
and combinations thereof. In embodiments in which the fiber is a
multicomponent fiber having an islands-in-the-sea configuration,
wherein either the islands, the sea or both comprise a
thermoplastic starch composition according to the present
invention. In embodiments, in which the islands are a thermoplastic
composition according to the present invention, the sea comprises a
different polymer. Non-limiting examples of such polymers include
those selected from the group consisting of: polyethylene
terephthalate; polyethylene; polypropylene; polyhydroxyalkanoate;
polylactic acid; polyester; and combinations thereof.
[0083] The fibers according to the present invention may be used
for any purposes for which fibers are conventionally used. This
includes, without limitation, incorporation into nonwoven webs and
substrates. The fibers hereof may be converted to nonwovens by any
suitable methods known in the art. Continuous fibers can be formed
into a web using industry standard spunbond type technologies while
staple fibers can be formed into a web using industry standard
carding, airlaid, or wetlaid technologies. Typical bonding methods
include: calendar (pressure and heat), thru-air heat, mechanical
entanglement, hydrodynamic entanglement, needle punching, and
chemical bonding and/or resin bonding. The calendar, thru-air heat,
and chemical bonding are the preferred bonding methods for the
starch and polymer multicomponent fibers. Thermally bondable fibers
are required for the pressurized heat and thru-air heat bonding
methods.
[0084] The fibers of the present invention may also be bonded or
combined with other synthetic or natural fibers to make nonwoven
articles. The synthetic or natural fibers may be blended together
in the forming process or used in discrete layers. Suitable
synthetic fibers include fibers made from polypropylene,
polyethylene, polyester, polyacrylates, and copolymers thereof and
mixtures thereof. Natural fibers include cellulosic fibers and
derivatives thereof. Suitable cellulosic fibers include those
derived from any tree or vegetation, including hardwood fibers,
softwood fibers, hemp, and cotton. Also included are fibers made
from processed natural cellulosic resources such as rayon.
[0085] The fibers described herein are typically used to make
disposable nonwoven materials for use in articles which may find
applications in one of many different uses. Specific articles of
the present invention include disposable nonwovens for hygiene and
medical applications, more specifically, for example, in
applications such as diapers, wipes, feminine hygiene articles,
drapes, gowns, sheeting, bandages and the like. In diapers,
nonwoven materials are often employed in the top sheet or back
sheet, and in feminine pads or products, nonwoven materials are
often employed in the top sheet. Nonwoven articles generally
contain greater than about 15% of a plurality of fibers that are
continuous or non-continuous and physically and/or chemically
attached to one another. The nonwoven may be combined with
additional nonwovens or films to produce a layered article used
either by itself or as a component in a complex combination of
other materials. Nonwoven articles produced from fibers can also
exhibit desirable mechanical properties, particularly, strength,
flexibility and softness. Measures of strength include dry and/or
wet tensile strength. Flexibility is related to stiffness and can
attribute to softness. Softness is generally described as a
physiologically perceived attribute which is related to both
flexibility and texture. One skilled in the art will appreciate
that the fibers according to the invention are also suitable for
use in applications other than nonwoven articles.
[0086] Notwithstanding the water stability of the fibers and other
articles produced in the present invention, the articles may be
environmentally degradable depending upon the amount of starch that
is present, any additional polymer used, and the specific
configuration of the article.
[0087] "Environmentally degradable" is defined as being
biodegradable, disintegratable, dispersible, flushable, or
compostable or a combination thereof. In the present invention, the
fibers, nonwoven webs, and articles may be environmentally
degradable.
[0088] A specific embodiment of a method according to the invention
is described. A starch is destructured by ethoxylation, and a
polyhydric alcohol, such as glycerol, is added to the destructured
starch. A liquid polyhydric alcohol such as glycerol can be
combined with destructured starch via a volumetric displacement
pump. The starch and polyhydric alcohol mixture is added to a mixer
and typically heated to at least 100.degree. C. over a period of
from about 1 to 5 minutes at about 60 rpm. Acid is added to the
mixer, with continued heating over a period of from about 1 to
about 15 minutes at about 60 rpm. Alternatively, multiple feed
zones can be used for introducing starch, polyhydric alcohol, and
acid, or premixtures thereof, directly to an extruder. The
resulting mixture of starch, polyhydric alcohol and acid is
extruded as a rod and chopped into pellets using any suitable
cutting device including, but not limited to, a knife. After from
about 18 to about 36 hours, the pellets are placed in an extruder.
The extruder barrel is preheated to at temperature of about
100.degree. C. to about 200.degree. C. Fibers are extruded by melt
spinning at a temperature sufficient to flash off residual water
and render the fibers water stable.
[0089] The starch-containing compositions and process of the
present invention can also be used to make forms other than fibers,
such as, but not limited to, films and molded articles using
conventional techniques known in the art.
EXAMPLES
[0090] The examples below further illustrate the present
invention.
Example 1
[0091] This example demonstrates melt mixing and one-shot spinning
of water stable fibers. The following materials are mixed in a
Haake Rheocord 90 melt mixer, Thermo Electron Corporation,
Newington, N.H.:
30 g Ethylex.TM. 2015 hydroxyethylated starch (Tate& Lyle,
Decatur, Ill.) 12.5 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
7.5 g Stearic Acid (Aldrich Chemicals, St. Louis, Mo.) 7.5 g Adipic
Acid (Aldrich Chemicals, St. Louis, Mo.)
[0092] The starch and the glycerol are mixed for about 3 minutes at
about 60 rpm at a temperature of about 160.degree. C. The balance
of components is added and mixed for an additional 7 minutes at
about 60 rpm. The contents are removed and allowed to cool to room
temperature. The mixture is then chopped using a knife into pieces
approximately 50 mm in diameter.
[0093] After 24 hours, the pieces are placed into a piston/cylinder
one shot spinning system, Alex James, Inc. of Greer, S.C. The
extruder barrel is preheated to 160.degree. C. The spinneret
capillary is 0.016'' diameter and has an L/D of 3. Fibers are
extruded by activating the piston at an extrusion rate of
approximately 0.8 g/minute. Approximately 50 g of fibers are
collected.
[0094] Approximately 20 g of the fibers are dried in a vacuum oven
at 90.degree. C. and 30 mm Hg for 12 hours. Another 20 g of the
fibers are dried in a convection oven at 115.degree. C. for 12
hours. The remaining 10 g of fibers are simply allowed to cool for
12 hours at ambient air temperature (about 22.degree. C.). The
respective fibers are subjected to the water stability test as
described herein. The fibers which are dried at elevated
temperature (90.degree. C. and 115.degree. C.) do not dissolve or
break-up, displaying water stability as defined herein. Fibers that
are allowed simply to cool, without heat treatment, break up
completely after 1 hour in water.
Comparative Example 2
[0095] This example demonstrates a conventional process for melt
mixing and one-shot spinning of starch fibers which are not water
stable. The following materials are mixed in the described Haake
Rheocord 90 melt mixer:
30 g Ethylex.TM. 2015 starch (Tate& Lyle, Decatur, Ill.) 12.5 g
Glycerol (Aldrich Chemicals, St. Louis, Mo.)
[0096] The starch and the glycerol are mixed for about 10 minutes
at about 60 rpm at a temperature of about 160.degree. C. The
contents are removed and allowed to cool to room temperature. The
mixture is then chopped using a knife into pieces approximately 50
mm in diameter. After 24 hours, the pieces are placed into the
described piston/cylinder one shot spinning system. The extruder
barrel is preheated to 160.degree. C. The spinneret capillary is
0.016'' diameter and has an L/D of 3. Fibers are extruded by
activating the piston at an extrusion rate of approximately 0.8
g/minute. Approximately 40 g of fibers are collected.
[0097] Approximately 10 g of the fibers are dried in a vacuum oven
at 90.degree. C. and 30 mm Hg for 12 hours. Another 10 g of the
fibers are dried in a convection oven at 115.degree. C. for 12
hours. The remaining 10 g of fibers are simply allowed to cool for
12 hours at ambient air temperature (about 22.degree. C.). The
fibers are subjected to the described water stability test. In this
case, the fibers that are dried at elevated temperature (90.degree.
C. and 115.degree. C.) and those that are allowed to cool to
ambient temperature all break up completely after 1 hour in
water.
Example 3
[0098] This example demonstrates melt mixing and one-shot spinning
of water stable starch fibers of various compositions. The
following materials are mixed in the described Haake Rheocord 90
melt mixer in a manner as described in Example 1 and melt blended.
Approximately 50 g of each composition is made.
TABLE-US-00001 Adipic Acid Ethylex .TM. Glycerol Lauric Acid
(Aldrich 2015 starch (Aldrich (Aldrich Chemicals, Material,
(Tate& Lyle, Chemicals, St. Chemicals, St. St. wt % Decatur,
IL) Louis, MO) Louis, MO) Louis, MO) Sample 1 60 25 12.5 2.5 Sample
2 60 25 10 5 Sample 3 60 25 7.5 7.5
[0099] After 24 hours, the materials are spun into fibers using the
described piston/cylinder one shot spinning system. The extruder
barrel is preheated to 160.degree. C. The spinneret capillary is
0.016'' diameter and has an L/D of 3. Fibers are extruded by
activating the piston at an extrusion rate of approximately 0.8
g/minute. Approximately 40 g of fibers of each composition are
collected.
[0100] Approximately 20 g of each composition of fibers are dried
in a convection oven at 115.degree. C. for 12 hours, and about 10 g
of each composition of fibers are simply allowed to cool for 12
hours at ambient air temperature (about 22.degree. C.). The fibers
are subjected to the described water stability test, with the
following results:
TABLE-US-00002 Result of water Result of water stability stability
test for test for heat treated untreated fibers Material fibers (2
weeks) (2 weeks) Sample 1 Pass Fail Sample 2 Pass Fail Sample 3
Pass Fail
Example 4
[0101] This example demonstrates additional blending and spinning
of fibers with water stability. The following materials are
used:
3500 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0102] 1095 g Glycerol (Aldrich Chemicals, St. Louis, Mo.) 438 g
Adipic acid (Solutia Chemicals, St. Louis, Mo.) 438 g Stearic acid
(Aldrich Chemicals, St. Louis, Mo.) 50 g Magnesium stearate
(Aldrich Chemicals, St. Louis, Mo.)
[0103] The starch, adipic acid, stearic acid and magnesium stearate
(employed as a process aid) are dry mixed in a Henschel Raw
Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition stated above. The screw
speed is set at 90 rpm with the thermal profile as shown below:
TABLE-US-00003 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0104] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For single component fibers, both extruders are
set to identical conditions as follows and the same material is fed
into both extruders:
TABLE-US-00004 Extruder Melt Melt Barrel Barrel Barrel Extruder
Pump Spin Pressure Zone 1 Zone 2 Zone 3 Pressure Speed Head (psi)
(.degree. C.) (.degree. C.) (.degree. C.) (psi) (rpm) (.degree. C.)
Set Extruder 1 1400 160 160 160 1500 464 165 Set Extruder 2 1400
160 160 160 1500 464
[0105] Fibers are collected in free fall at a mass throughput of
0.8 g/hole-min. The fibers are collected and dried overnight in a
convection oven at 115.degree. C. The fibers are subjected to the
water stability test. All fibers pass the water stability test.
Example 5
[0106] This example demonstrates blending and spinning of
bicomponent fibers with water stability. The following materials
are used to produce a thermoplastic composition:
3500 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0107] 1095 g Glycerol (Aldrich Chemicals, St. Louis, Mo.) 438 g
Adipic acid (Solutia Chemicals, St. Louis, Mo.) 438 g Stearic acid
(Aldrich Chemicals, St. Louis, Mo.) 50 g Magnesium stearate
(Aldrich Chemicals, St. Louis, Mo.)
[0108] The starch, adipic acid, stearic acid and magnesium stearate
are dry mixed in a Henschel Raw Material Mixer (Green Bay, Wis.)
for 4 minutes at 1000 rpm. The mixture is then fed into the
described B&P Process System Twin Screw Extrusion Compounding
System. Glycerol is fed through a liquid feed port at a rate that
maintains the desired composition stated above. The screw speed is
set at 90 rpm with the thermal profile as employed in Example
4.
[0109] The overall extrusion rate is 20 lbs/hour. A vacuum line is
applied to two of three vent ports to extract water from the
material during pelletization. Torque is 10%. The mixture is
extruded into strands 0.3-0.8 cm in diameter and the strands are
chopped to form pellets via a Conair pellitizer. The pellets are
dried for 12 hours in a through air dryer at 150.degree. F. The
pellets are fed in the described Hills 4-hole extruder test stand
with the bicomponent sheath/core 4-hole spin pack. For bicomponent
fibers, the thermoplastic composition as described above is fed
into extruder 1. In the second extruder a polylactic acid (PLA)
obtained from Natureworks LLC (Grade 6251D) is used, under the
following conditions:
TABLE-US-00005 Extruder Melt Melt Barrel Barrel Barrel Extruder
Pump Spin Pressure Zone 1 Zone 2 Zone 3 Pressure Speed Head (psi)
(.degree. C.) (.degree. C.) (.degree. C.) (psi) (rpm) (.degree. C.)
Set Extruder 1400 180 190 190 1500 464 190 1 (TPS) Set Extruder
1400 150 160 160 1500 464 2 (PLA)
[0110] This produces a 50/50 sheath/core fiber. The fibers are
collected in free fall at a mass throughput of 0.8 g/hole-min The
fibers are dried overnight in a convection oven at 115.degree. C.
The fibers are subjected to the water stability test. All fibers
passed.
Example 6
Fibers Blended with PP
[0111] This example demonstrates additional blending and spinning
of fibers with water stability. The following materials are
used:
6000 g Ethylex.TM. 2065 (Tate& Lyle, Decatur, Ill.)
[0112] 2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0113] 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 50 g
Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)
[0114] The solid components are dry mixed in a Henschel Raw
Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00006 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0115] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For single component fibers, both extruders are
set to identical conditions as follows and the same material is fed
into both extruders:
TABLE-US-00007 Extruder Melt Melt Barrel Barrel Barrel Extruder
Pump Spin Pressure Zone 1 Zone 2 Zone 3 Pressure Speed Head (psi)
(.degree. C.) (.degree. C.) (.degree. C.) (psi) (rpm) (.degree. C.)
Set Extruder 1400 125 160 170 1500 464 175 1 (.degree. C.) Set
Extruder 1400 125 160 170 1500 464 2 (.degree. C.)
[0116] Fibers are collected through an attenuating air jet set at
20 psi. A mass throughput of 0.75 g/hole-min is maintained. The
fibers are collected and dried overnight in a convection oven at
115.degree. C. The fibers are subjected to the water stability
test. All fibers pass the water stability test.
Example 7
[0117] This example demonstrates blending and spinning of
bicomponent fibers with water stability. The following materials
are used to produce a thermoplastic composition:
6000 g Ethylex.TM. 2065 (Tate& Lyle, Decatur, Ill.)
[0118] 2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0119] 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 50 g
Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)
[0120] The solid components are dry mixed in a Henschel Raw
Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00008 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0121] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00009 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0122] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratios are produced:
TABLE-US-00010 Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10
90 15 85 20 80
[0123] The fibers are collected and dried overnight in a convection
oven at 115.degree. C. The fibers are subjected to the water
stability test. All fibers pass the water stability test.
Example 8
Bicomponent Fibers with PP
[0124] This example demonstrates blending and spinning of
bicomponent fibers with water stability. The following materials
are used to produce a thermoplastic composition:
6000 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0125] 1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0126] 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 50 g
Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)
[0127] The solid components are dry mixed in a Henschel Raw
Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00011 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0128] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00012 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0129] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratios are produced:
TABLE-US-00013 Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10
90 15 85 20 80
[0130] The fibers are collected and dried overnight in a convection
oven at 115.degree. C. The fibers are subjected to the water
stability test. All fibers pass the water stability test.
Example 9
Binder Fibers
[0131] This example demonstrates additional blending and spinning
of binder fibers with water stability. The following materials are
used:
6000 g Ethylex.TM. 2015 (Tate & Lyle, Decatur, Ill.)
[0132] 2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.) 500 g
Maleated polypropylene (Eastman Chemicals, Kingsport, Tenn.) 50 g
Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)
[0133] The starch, adipic acid, maleated polypropylene and
magnesium stearate are dry mixed in a Henschel Raw Material Mixer
(Green Bay, Wis.) for 4 minutes at 1000 rpm. The mixture is then
fed into a B&P Process System Twin Screw Extrusion Compounding
System (Saginaw, Mich.) with 40 mm co-rotating screws. Glycerol is
fed through a liquid feed port at a rate that maintains the desired
composition (stated above). The screw speed is set at 90 rpm with
the thermal profile as shown below:
TABLE-US-00014 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0134] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For single component fibers, both extruders are
set to identical conditions as follows and the same material is fed
into both extruders:
TABLE-US-00015 Extruder Melt Melt Barrel Barrel Barrel Extruder
Pump Spin Pressure Zone 1 Zone 2 Zone 3 Pressure Speed Head (psi)
(.degree. C.) (.degree. C.) (.degree. C.) (psi) (rpm) (.degree. C.)
Set Extruder 1400 125 160 170 1500 464 165 1 (.degree. C.) Set
Extruder 1400 125 160 170 1500 464 2 (.degree. C.)
[0135] Fibers are collected in on a screen through an attenuating
air jet at a mass throughput of 0.8 g/hole-min. The air jet is set
at 20 psi. The Thermoplastic starch fibers are collected, chopped
with a knife to lengths approximately 2 cm. The starch fibers are
mixed with unbonded staple polyester fibers (Wellman, Fort Mill,
S.C.) at a ratio of 10:1 by weight polyester to starch web for a
total basis weight of approximately 50 gsm. The unbonded web is
placed in a Carver.TM. Press and pressed at 1000 psi at 165.degree.
C. for 10 minutes between Teflon sheets. The web is removed and
allowed to cool. The web is dried overnight in a vacuum oven at
115.degree. C. The web is subjected to the following water
stability test: A 5 cm.times.5 cm web is placed in 1000 ml of water
and allowed to soak for 24 hours. The web is removed and if it
remains intact, it is said to pass the water stability test. The
dried web passes the water stability test.
Example 10
Fibers Using Catalyst
[0136] This example demonstrates blending and spinning of
bicomponent fibers with water stability. The following materials
are used to produce a thermoplastic composition:
6000 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0137] 1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0138] 1.9 g p-Toluenesulfonic acid (Aldrich Chemicals, St. Louis,
Mo.) 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 50 g
Magnesium stearate (Aldrich Chemicals, St. Louis, Mo.)
[0139] The solid components are dry mixed in a Henschel Raw
Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00016 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0140] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00017 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0141] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratios are produced:
TABLE-US-00018 Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10
90 15 85 20 80
[0142] The fibers are collected and dried overnight in a convection
oven at 115.degree. C. The fibers are subjected to the water
stability test. All fibers pass the water stability test.
Example 11
[0143] This example demonstrates blending and spinning of
bicomponent fibers with water stability comprising triglycerides.
The following materials are used to produce a thermoplastic
composition:
6000 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0144] 1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0145] 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 500 g
Linseed oil (Aldrich Chemicals, St. Louis, Mo.) 50 g Magnesium
stearate (Aldrich Chemicals, St. Louis, Mo.)
[0146] All the components except glycerol are mixed in a Henschel
Raw Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00019 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0147] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00020 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0148] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratios are produced:
TABLE-US-00021 Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10
90 15 85 20 80
[0149] The fibers are collected and dried overnight in a convection
oven at 115.degree. C. The fibers are subjected to the water
stability test. All fibers pass the water stability test.
Example 12
[0150] This example demonstrates blending and spinning of
bicomponent fibers with water stability comprising triglycerides.
The following materials are used to produce a thermoplastic
composition:
6000 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0151] 1900 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
500 g Polypropylene Profax.TM. PH835 (Basell, Elkton, Md.)
500 g Maleated Polypropylene G3003 (Eastman Chemicals, Kingsport,
Tenn.)
[0152] 500 g Adipic acid (Solutia Chemicals, St. Louis, Mo.) 200 g
Soybean oil (Aldrich Chemicals, St. Louis, Mo.) 50 g Magnesium
stearate (Aldrich Chemicals, St. Louis, Mo.)
[0153] All the components except glycerol are mixed in a Henschel
Raw Material Mixer (Green Bay, Wis.) for 4 minutes at 1000 rpm. The
mixture is then fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00022 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0154] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00023 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0155] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratios are produced:
TABLE-US-00024 Sheath (PP) (% volume) Core (TPS) (% volume) 5 95 10
90 15 85 20 80
[0156] The fibers are collected and dried overnight in a convection
oven at 115.degree. C. The fibers are subjected to the water
stability test. All fibers pass the water stability test
Example 13
Web from TPS Fibers
[0157] TPS fiber prepared as in example 8 with a core sheath ratio
of 95/5 TPS/PP. Webs of approximately 60 grams/m.sup.2 are bonded
via heated calender with diamond shaped pattern (1 mm in width, at
2 mm intervals) at 60.degree. C. The webs are dried in a oven at
115.degree. C. for 12 hours. A 5 cm.times.5 cm piece of the web is
put into 1000 ml of tap water and stirred at 30 rpm for 24 hours.
The web is removed from the water dried in air for 24 hours then
measured. The length and width dimension changes by no more than
15% and the web is essentially intact. The web is said to display
water stability.
Comparative Example 14
[0158] Web from Non-Water Stable TPS Fibers
[0159] The following materials are used to produce a thermoplastic
composition:
6000 g Ethylex.TM. 2015 (Tate& Lyle, Decatur, Ill.)
[0160] 2500 g Glycerol (Aldrich Chemicals, St. Louis, Mo.)
[0161] The starch is fed into a B&P Process System Twin Screw
Extrusion Compounding System (Saginaw, Mich.) with 40 mm
co-rotating screws. Glycerol is fed through a liquid feed port at a
rate that maintains the desired composition (stated above). The
screw speed is set at 90 rpm with the thermal profile as shown
below:
TABLE-US-00025 zone zone zone zone zone zone zone zone zone
Temperature 1 2 3 4 5 6 7 8 9 die Set (.degree. C.) 85 85 100 145
155 160 160 160 140 100 Actual (.degree. C.) 83 83 85 138 138 144
155 147 133 98
[0162] At these conditions the overall extrusion rate is 20
lbs/hour. A vacuum line is applied to two of three vent ports to
extract water from the material during pelletization. Torque is
10%. The mixture is extruded into strands 0.3-0.8 cm in diameter
and the strands are chopped to form pellets via a Conair
pellitizer. The pellets are dried for 12 hours in a through air
dryer at 150.degree. F. The pellets are fed into a Hills 4-hole
extruder test stand (Hills, Inc., West Melbourne, Fla.) with a
Hills bicomponent sheath/core 4-hole spin pack. The equipment
features two extruders that feed to a single spin head to produce
bicomponent fibers. For bicomponent fibers, the thermoplastic
composition as described above is fed into extruder 1. In the
second extruders a polypropylene Profax.TM. PH835 (Basell) is used,
under the following conditions:
TABLE-US-00026 Extruder Melt Barrel Barrel Barrel Extruder Spin
Pressure Zone 1 Zone 2 Zone 3 Pressure Head (psi) (.degree. C.)
(.degree. C.) (.degree. C.) (psi) (.degree. C.) Set Extruder 1400
125 160 170 1500 175 1 (.degree. C.) TPS Set Extruder 1400 165 170
175 1500 2 (.degree. C.) PP
[0163] Fibers are collected through an attenuating air jet set at
20 psi. A total mass throughput of 0.75 g/hole-min is maintained.
Adjusting the ratio of the melt pump speeds can produce sheath core
fibers of different sheath thicknesses. The following sheath/core
volume ratio is produced:
TABLE-US-00027 Sheath (PP) (% volume) Core (TPS) (% volume) 5
95
[0164] Webs of approximately 60 grams/m.sup.2 are bonded via heated
calender with diamond shaped pattern (1 mm in width, at 2 mm
intervals) at 165.degree. C. The webs are dried in a oven at
115.degree. C. for 12 hours. A 5 cm.times.5 cm piece of the web is
put into 1000 ml of tap water and stirred at 30 rpm for 24 hours.
The web is removed from the water dried in air for 24 hours then
measured. The length and width dimension changes by more than 15%
and the web is not essentially intact with missing pieces. The web
is said to not display water stability.
[0165] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
discloses as "40 mm" is intended to mean "about 40 mm".
[0166] All documents cited in the Detailed Description of the
Invention are, in relevant part, incorporated herein by reference;
the citation of any document is not to be construed as an admission
that it is prior art with respect to the present invention.
[0167] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *