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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to regenerated starch in fiber form. More
particularly, the invention relates to water insensitive starch fibers
prepared from modified or unmodified starches containing from about 55 to
100% by weight amylopectin, and to a process of making the same.
Starch is a polymer comprising a plurality of anhydroglucose units arranged
in one of two structural forms: as a linear chain polymer called amylose
or as a highly branched polymer called amylopectin. The properties of
these two forms of starch differ and much of the difference may be traced
to the affinity of the hydroxyl groups in one particular structural
molecule for those in another. Thus, in linear chain polymers such as
amylose, the straight chains can orient in parallel alignment so that a
large number of the hydroxyl groups along one chain are in close proximity
to those on adjacent chains. When this happens, the hydroxyl groups form
associations through hydrogen bonds and the chains are bound together
forming aggregates which are insoluble in water. In very dilute solutions,
the aggregated chains of amylose will precipitate; in more concentrated
solutions, a gel will form. This essentially crystalline process of
alignment, association and precipitation or gelling is known as
retrogradation. Because of the linearity of amylose and its marked
tendency to form associated aggregates, this material is insoluble in
water and forms strong, flexible films.
In contrast, the highly branched chains of the amylopectin molecules cannot
align and associate so readily. Consequently, amylopectin tends to be
soluble in water, forming solutions that will not gel under normal
conditions. However, prolonged aging or special conditions such as
freezing may effect retrogradation in some dispersions containing
amylopectin.
Principally due to these differences in the solubility properties of the
two structural starch forms, previous attempts to produce
water-insensitive starch fibers or films have been directed to starches
containing substantial quantities of amylose. Thus, U.S. Pats. Nos.
2,902,336, 3,030,667, 3,336,429, and 3,116,351 among others, although
differing in techniques for producing fibers, all have in common the use
of starches containing at least 50%, and generally 80 to 100%, by weight
amylose. The methods of these patents therefore rely on the linear chain
amylose portion of the starch to provide the water-insensitive properties
of the final fiber and any amylopectin present is treated as an impurity,
tolerable in only minor quantities. However, it is well known in the art
that such grades of starch containing 80 to 100% amylose do not occur
naturally and are only obtained by subjecting starch to treatments wherein
a substantial portion (i.e. that portion comprising amylopectin) is
discarded, thereby rendering the manufacture and use of such fibers on a
commercial scale economically disadvantageous.
Other methods for the preparation of starch containing fibers such as by
plasticizing starch dispersions with softeners or fluxes to convert them
into "pseudothermoplastics" or by thermally decomposing the starch to form
a starch xanthate fiber have been taught in U.S. Pats. Nos. 2,570,449 and
3,497,584 respectively. Such methods require complicated processing
conditions and some do not necessarily result in the production of
water-insensitive fibers.
It is therefore an object of the present invention to provide a process for
the production of water-insensitive starch fibers in which the presence of
amylopectin is not deleterious.
It is another object to provide a process which produces starch fibers from
starches which do not contain relatively high concentration of the linear
chain polymer, amylose.
It is also an object to provide a process which produces starch fibers from
naturally occurring starches, and hence is economical and efficient.
Another object is to provide such a process which produces starch fibers
from 100% amylopectin.
Another object is to provide a process which produces starch fibers which
are strong and durable as well as water-insensitive.
A further object is to provide a process whereby a variety of
water-insoluble materials may be incorporated into a starch dispersion and
subsequently encapsulated within the fiber matrix during its formation for
the purpose of imparting a wide variety of functional characteristics to
the final fiber.
Yet another object is to provide starch fibers which possess superior
properties and which may be produced in discrete lengths and used as
supplements to or replacements for natural cellulose fibers in a
papermaking process.
These and other related objects will be apparent from the descriptions
which follow.
SUMMARY OF THE INVENTION
In accordance with the present invention, water-insensitive starch fibers
having an amylopectin content from about 55 to 100% by weight are prepared
by extruding a thread-like stream of a collodial dispersion of the starch
at 5 to 40% by weight solids into a moving coagulating bath. The
coagulating bath employed comprises an aqueous solution containing at
least one coagulating salt, such as ammonium sulfate, ammonium sulfamate,
mono-basic ammonium phosphate, di-basic ammonium phosphate or mixtures
thereof, the solution containing such coagulating salts in an amount at
least sufficient to coagulate the starch. Fibers may be produced in
desired lengths and widths by varying any of a number of process
parameters as will be discussed in detail herein below.
Contrary to what would be expected based on the high amylopectin content of
the starch employed, the starch fibers produced in accordance with the
present invention are surprisingly water-insensitive and may be used in a
variety of aqueous systems without losing their integrity. By the term
"water-insensitive fiber" as used herein is meant that the resultant
fibers are of sufficient integrity to allow for complete separation of the
fiber from the aqueous slurry and recovery thereof. Additionally, the
fibers will retain their integrity in aqueous slurries or dispersions
under pH condition of 4.0 to 9.5 even after removal of the coagulating
salt, and even at temperature as high as 40 to 72.degree. C., depending
upon the base starch. Moreover, these discontinuous filaments possess
sufficient durability and shear-insensitivity such that they can be
recovered in dry form or transported as an aqueous slurry or wet-slab and
subsequently incorporated into conventional papermaking processes eiter
alone or in combination with a variety of natural and/or synthetic staple
fibers to produce paper-like sheets or webs as well as textiles, molded
products, and other related applications.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The starch employed in the present invention may be any starch containing
from about 55 to 100% by weight amylopectin. For reasons of economy and
availability, naturally occurring starches containing from about 64 to
100% amylopectin are preferred. In particular, corn starch (64-80%
amylopectin) is employed; although waxy maize (93-100% amylopectin), rice
(83-84% amylopectin), potato (about 78% amylopectin), tapioca (about 83%
amylopectin), wheat (73-83% amylopectin), etc. may also be used. Mixtures
of the starch bases may also be utilized as may mixtures of the
fractionated components resulting in a total level of at least about 55%
amylopectin.
The concentration of the starch solids in the dispersion will preferably be
about 5 to 40% by weight. While higher concentrations of starch solids may
be used, the resulting dispersions become very viscous and special
equipment is required to handle them.
The particular starch employed must be used in the form of a collodial
dispersion. For the purposes of this invention, the term "colloidal
dispersion" means a dispersion of starch which is substantially free of
granules and which exhibits, on standing at the temperature at which it is
to be used, little evidence of gelation or precipitation. This state of
dispersion may be obtained using a variety of techniques depending upon
the particular starch base employed, the desired end use and the equipment
available.
When native starches that are very high in amylopectin content, such as
waxy maize, are employed, a suitable colloidal dispersion may be prepared
merely by thoroughly cooking the starch in water with no chemical
additives or modifications required. In most cases where starches which
contain less than about 95% amylopectin are employed, it will be desirable
to chemically derivatize or modify the starch to ensure its colloidal
dispersion before adding it to the aqueous system. The derivatization or
modification is carried out to an extent which will insure the production
of the desired colloidal dispersion without affecting the ability of the
starch to subsequently precipitate. Alternatively, if there is no
objection to the presence of caustic in the system, the latter starches
may be dispersed in aqueous sodium hydroxide, potassium hydroxide or other
common alkali. As further alternatives, the starch bases may also be
dispersed in a minor amount of an organic solvent such as
dimethlysulfoxide and then added to water, or the starch base may be
dispersed in conjunction with chemical additives such as urea and/or
paraformaldehyde. In the cases where causticizing is employed, the amount
of alkali used must be sufficient to adequately disperse the starch.
Typical amounts of alkali used when sodium hydroxide is employed are from
15 to 40%, by weight, based on the weight of the starch.
In preparing the starch dispersion, the starch is added to the dispersing
medium and vigorously agitated until a state of colloidal dispersion is
achieved. In the case of dilute dispersions of starch (i.e. about 5-10%
starch solids by weight), this will require about 45 minutes, with longer
periods and/or moderate heat required for more concentrated starch
dispersions or for certain chemically modified starch bases.
Most of the starch dispersions, including those prepared by cooking waxy
maize and most of the chemically modified starches, may be cooled to room
temperature prior to introduction into the coagulating bath. In the case
of a few of the less chemically modified starches, it will be preferred to
employ the dispersions at approximately the elevated temperatures at which
they are prepared so as to maintain the colloidal dispersion and to insure
efficient fiber production.
The coagulating bath used in preparing the starch fibers according to the
present invention comprises an aqueous solution containing specific
ammonium salts selected from the group consisting of ammonium sulfate,
ammonium sulfamate, mono- and di-basic ammonium phosphate and mixtures
thereof. It is also possible to combine the above-mentioned functional
salts with other compatible salts which will form a starch precipitate so
as to obtain satisfactory coagulation and a fibrous product. Suitable
salts for this purpose include ammonium persulfate, ammonium carbonate,
ammonium bromide, ammonium bisulfite, ammonium nitrite, ammonium nitrate,
ammonium bicarbonate, ammonium oxalate, sodium and potassium chloride,
sodium and potassium sulfate, among others. Generally no advantage is seen
in using these additional salts since the ammonium sulfate, sulfamate or
phosphate salts must still be present in their respective minimum amount
in order to effect coagulation. The only instances where the presence of
substantial amounts of other salts may be desirable is in the use of the
recycled coagulation bath wherein salts are present which have been
generated in situ, as will be discussed hereinbelow.
minimum concentration of the salt required to effect coagulation as well as
the preferred salt or salt blend will vary depending upon the particular
starch base employed. For example, in the case of waxy maize starch, it is
necessary for ammonium sulfate to be present in amounts of at least 35%,
by weight of the total solution, ammonium sulfamate 72% (saturation),
dibasic ammonium phosphate 37% and mono-basic ammonium phosphate 40%. In
the case of corn starch or similar starches containing about 64-80%
amylopectin, lower concentrations of salt may be used with ammonium
sulfate required in amounts of 20%, ammonium sulfamate 50%, mono-basic
ammonium phosphate 25% and di-basic ammonium phosphate 30%.
It will be recognized that alkali salts are generated in the coagulating
bath when causticized starch dispersions are employed, with satisfactory
production of the desired starch fibers continuing until the level of the
generated salt is relatively high. The generated salt tolerance level
above which production of the fibers becomes inefficient will vary
depending upon such factors as the specific salt employed, the total salt
solids employed, the starch solid concentration in the dispersion, the
amount of amylopectin in the starch base, etc. Once this salt tolerance
level is determined, a steady-state system may be achieved at this maximum
level (or less) by the periodic addition of ammonium sulfate on a
continuous basis. As an example, when sodium hydroxide is used as a
dispersing medium and the starch mixture is extruded into an ammonium
sulfate coagulating bath, sodium sulfate is generated. In this case, it
has been found that production of corn starch fibers (13% solids
dispersion) will continue at a satisfactory level until a maximum of about
70 parts sodium sulfate per 30 parts ammonium sulfate (44% solids
solution) is present in the bath. Above this level of sodium sulfate,
production of the starch fibers becomes less efficient and the resulting
fibers tend to lose their individual integrity. However, by adding a small
amount of an inorganic acid to the initial coagulating bath or to the bath
during formation of the fibers, the level of the generated salt in the
system may be appreciably raised before production of the fibers is
seriously affected. Thus, using the example described previously, the
addition of as little as 3 parts of sulfuric acid per hundred parts of the
initially charged coagulating bath salt results in a tolerance level of 90
parts sodium sulfate per 10 parts ammonium sulfate thereby increasing the
longevity of the coagulating bath.
It is apparent that the salt solution used in the fiber forming process may
be recycled and used again once the fibers have been removed. In this
regard, the starch dispersions which do not contain caustic present little
difficulty in recycling other than that the solids concentration of the
salt be maintained. However, in those cases where causticized starch
dispersions are employed, chemical reactions with the coagulating solution
will occur. For example, if ammonium sulfate is used, the reaction results
in the formation of ammonium gas and sodium sulfate. The recycling of such
a system can be extended by recovering the ammonia in an acid scrubber and
returning it to the system as ammonium sulfate. The generated sodium
sulfate can be used in the coagulating bath as part of the salt blend
until the tolerance levels discussed previously are attained or can be
used as a raw material in pulp or papermaking operations e.g. as "salt
cake" in the production of Kraft pulp.
Starch fibers can be produced at any temperature at which the starch
dispersion can be handled. Generally, the coagulation bath is maintained
at about room temperature (20.degree. C), however, temperatures as high as
about 70.degree. C. may be used. These higher temperatures may be desired
under certain conditions since they increase the solubility of the salt in
the coagulating bath resulting in more concentrated solutions. Thus, when
it is desired to produce waxy maize fibers using mono-basic ammonium
phosphate as coagulant, it is desirable to increase the temperature of the
bath so as to obtain a concentration of salt of approximately 40%
(saturation level for the mono-basic ammonium phosphate at 20.degree. C.
is 28%).
In preparing the starch fibers of the invention, the starch dispersion is
introduced continuously or by drops in the form of a thread-like stream
into the moving coagulating salt solution. This introduction may be
accomplished from either above or below the salt solution using any
conventional techniques. Thus, the dispersion may be extruded through an
apparatus containing at least one aperture, such as a spinnerette, a
syringe or a biuret feed tube. Alternatively, the dispersion may be
discharged under pressure from a pipe or tube containing a plurality of
apertures into a surrounding enclosed area, e.g. a concentric pipe,
containing the moving coagulating solution. Various adaptions of the above
and related techniques may be used and the fibers may be thus produced
using either batch or continuous operations.
In accordance with either embodiment, the aqueous salt coagulating solution
should be moving when the starch dispersion is introduced and the
directionality of the two flows can also be utilized in controlling fiber
lengths and diameters or widths. Thus, if the salt solution is moving in a
direction generally concurrent with the flow of the starch dispersion,
relatively round fiber lengths are formed; if the starch dispersion is
introduced at an angle of about 90.degree. to the flow of the salt
solution, relatively flatter fibers are formed. Generally apertures of 10
to 500 microns in diameter are preferred, particularly when the fibers are
to be used in papermaking operations.
It is also possible to control the length and width of the fibers by
varying the relative flow velocities of the two liquid components. As an
example, if the starch dispersion is extruded through an aperture of 337
microns and the ratio of the velocity of the salt solution to the velocity
of the starch dispersion is 0.92, fiber diameters of 610 microns may be
produced. Increasing the velocity ratio to 2.985 (maintaining all other
parameter control) can result in fiber diameters averaging about 113
microns. Similar relationships have been found with respect to the length
of the fibers and fibers varying in length from 0.05 mm. to 16 cm. have
been produced. When the starch fibers are produced for subsequent use in
papermaking operations, it is generally desirable to obtain fibers in
lengths of from about 0.1 to 3.0 mm. and widths of 10 to 500 microns.
It will be recognized that the length, cross-sectional size and
configuration of the resultant fibers are dependent upon a number of
interrelated parameters in addition to those described hereinabove. Thus,
the viscosity, the solids content of the starch dispersion, as well as the
particular components used in the coagulating solution and/or stach
dispersion are additional factors which can be used in conjunction with
the parameters discussed previously in order to control the dimensions of
the resultant fiber.
Depending upon the desired end use of the fibers, the method of recovery
thereof may vary. Thus, the aqueous suspension or slurry of fibers may be
used directly, such as by introducing it into the pulp stream, thereby
enabling complete integration of the fiber production into the paper
manufacturing plant. The fibers may also be recovered in the dry state,
for example, by collecting the fibers from water on a screen or similar
device. It is then preferable to reslurry the fibers into a non-aqueous
solvent such as methanol, ethanol, isopropanol, acetone or the like in
which the fibers are not soluble. The fibers are then recovered, as by
filtration, from the solvent and dried. Other methods such as
centrifuging, flash-drying or spray-drying may also be used to remove the
water. Once dried, the fibers may be re-introduced into an aqueous medium
and will exhibit excellent re-dispersibility maintaining their discrete,
discontinuous structure. Alternatively, the fibers may be recovered from
the slurry, as by filtration, washed and placed in water at levels of up
to about 50% solids and formed into "wet slabs" for subsequent use.
As a further embodiment of the present invention, the starch employed may
be chemically treated to vary the properties of the fiber produced or to
help effect formation of the colloidal dispersion. Alternatively, the
starch fibers may be treated after formation in order to produce certain
functional characteristics. Thus, the starch may be chemically treated, as
by aminoethylation, in order to provide rapid dispersibility of the starch
in the dispersion, which treatment will also result in the production of a
fiber which possesses a cationic charge when employed in an aqueous
medium. Similarly, a starch may be used which is modified to contain
anionic groups so as to be stable in a dispersion and which will produce a
fiber having anionic properties. The fibers may also be modified after
their formation in order to achieve specific functional properties. Thus,
improved anionic functionality might be obtained by bleaching the fibers
after precipitation as long as the conditions are not so severe as to
destroy the fibers. The properties of the fibers may also be controlled by
using blends of modified and unmodified starches or by the addition of
other functional materials, such as polyacrylic acid, to obtain the
specifically desired properties.
It is also possible to incorporate in the dispersing medium certain
hydrocolloids and to extrude the hydrocolloid together with the starch in
order to produce a starch-hydrocolloid fiber. In order to achieve this
combination fiber, it is only necessary that the hydrocolloid (in minor
amounts, i.e. less than 50% by total solids weight), together with the
starch, be placed in a state of colloidal dispersion prior to contact with
the coagulating bath. Thus, in the case of water-dispersible hydrocolloids
such as polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose,
etc., it is only necessary to add the hydrocolloid to the water in which
the starch is dispersed. In the case of other hydrocolloids, such as
casein, it will be necessary to causticize the dispersion in order to form
the colloidal dispersion required.
As an alternative embodiment of the present invention, water-insoluble
additives may be uniformly admixed throughout the starch dispersion and
subsequently encapsulated within the resultant starch fiber. Thus,
water-insoluble additives including pigments, metallic powders, latices,
oils, plasticizers, microspheres (glass beads, foamed silica or other low
density materials either in blown or unblown form), etc., may be
encapsulated within the starch fibers of the invention. In a similar
manner, water-insoluble synthetic polymers or latices, such as polyvinyl
acetate, polyacrylonitrile, polystyrene, etc., may be incorporated within
the fiber. It will also be noted that the density of the starch fibers may
be varied by incorporating air or other gases in the starch dispersion
prior to passing it into the coagulating bath.
It is further noted that certain water-soluble solid additives may also be
co-extended with the starch fibers. In such cases, the additive will be
dissolved in the aqueous starch dispersion and the coagulating bath which
is employed in forming the starch fibers will be adjusted by the addition
of a sufficient quantity of a compatible salt capable of precipitating the
additive. As an example, a commercial rosin size can be added to the
starch dispersion and extruded into a coagulating bath containing the
functional starch-coagulating salt together with sufficient aluminum
sulfate to precipitate the rosin thereby forming a co-precipitated
starch-aluminum rosinate fiber.
The water-insolubility of the starch fibers of the present invention can be
further enhanced by the incorporation of conventional cross-linking
agents, such as urea-formaldehyde, glyoxal, urea-melamine-formaldehyde,
Kymene (registered tradename of Hercules Inc., Wilmington, Delaware), etc.
These cross-linking agents may be incorporated into the starch dispersion
prior to extrusion or may be post-added to the starch fiber.
In all the above described embodiments, the amount of additive to be
incorporated into the starch dispersion will vary over a wide range
depending upon the specific additive and the desired end use. Thus,
amounts of additive as little as about 0.01% to as high as about 80% may
be employed and incorporated into the starch fibers.
The resultant discontinues starch fibers possess sufficient integrity,
durability and shear insensitivity that they may be readily utilized in a
variety of applications including textiles, molded products, etc., as well
as in the papermaking operation described in our co-pending application
Ser. No. 670,360 filed Mar. 25, 1976 now abandoned.
The starch fibers of this invention and the process for making the same are
illustrated further by the following examples which are not, however,
intended to limit the scope of the invention. Unless otherwise stated, all
parts in the examples are by weight.
EXAMPLE 1
A slurry was prepared using an unmodified waxy maize starch containing
essentially 100% amylopectin in water at a 15% solids level. The slurry
was then placed on a boiling water bath and cooked at 96.degree. C. with
mechanical agitation for a period of 30 minutes. After cooking, the
resulting starch dispersion was cooled to 22.degree. C., and its
viscosity, measured with a RVF Brookfield Viscometer, was found to be 5000
cps. at 20 RPM.
The starch dispersion was then extruded at 703.08 gms./cm..sup.2 pressure
from a stainless steel spinnerette containing 100 apertures, each of which
had a diameter of 204.2 microns. The dispersion was extruded at an angle
of approximately 90.degree. into an agitated aqueous coagulating bath
consisting of a 44% by weight aqueous solution of ammonium sulfate
maintained at room temperature. The extrusion process was continued for a
period of 30 minutes and the resultant discontinuous fibers were agitated
in the salt solution for an additional hour.
Thereafter the fibers were recovered from the salt solution by collecting
them on a 100 mesh stainless steel screen and washed free of salt with
water. The fibers at this point may be introduced directly into a
papermaking process or consolidated into wet mat form at approximately 50%
solids.
Alternatively, the fibers may be reclaimed in dry form after recovery from
the salt solution by introducing them into a solution of ethyl alcohol and
mixing for a period of 10 minutes.
The fibers may then be recovered from the alcohol solution by using screen
filtration techniques and either air or oven dried.
The discontinuous fibrous products formed by the previously described
techniques were found to possess a cross-sectional diameter averaging
approximately 100 microns and a length distribution between 500 and 3000
microns. The procedure produced a satisfactory starch fiber product, i.e.
the fibers were water-insensitive and, after drying, were readily
redispersible in water while retaining their original structure and
configuration.
EXAMPLES 2-22
These examples show the use of a variety of starch bases and dispersion
methods in the process of the present invention.
The basic procedure described in Example 1 was duplicated using the
materials, dispersing methods and parameters shown in Table I.
In all cases, the resultant fibers were water-insensitive and exhibited
other satisfactory starch fiber properties.
EXAMPLES 23-26
These examples illustrate the effect of varying the angle of entry of the
starch stream into the coagulating bath.
In the four examples which follow, a 10% solids dispersion of unmodified
corn starch was prepared by dispersing in a 15% solids caustic solution.
The resulting dispersion, having a viscosity of 2100 cps., was extruded
under 2812.32 gm/cm.sup.2 pressure through a spinnerette having apertures
204.2 microns in diameter. The basic procedure described in Example 1 was
repeated using the parameters shown in Table II.
TABLE I
__________________________________________________________________________
Approximate
Starch Angle Avg. Fiber
Ex. Starch
Dispersion
Viscosity
Aperture
of Salt Diameter
Pressure
No.
Starch Base
Solids
Technique
at 22.degree. C
Size (.mu.)
Entry
Type % (microns)
gms/cm.sup.2
__________________________________________________________________________
2 Acid converted
38% cook 6020 cps
204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
100 1406.16
waxy maize
3 Aminoethylated
10% cook 10,000
204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
75 1406.16
corn
4 Corn 10% 15% caustic
2365 337.5
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
150 703.08
5 Potato 10% 15% caustic
875 102.1
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
75 703.08
6 Tapioca 7.5%
15% caustic
1500 102.1
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
100 703.08
7 Aminoethylated
10% 15% caustic
1500 102.1
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
100 703.08
potato
8 Amylon 5.sup.(1)
13% 40% caustic
2620 337.5
45.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
450 2109.24
9 Amylon 5
13% 40% caustic
2620 204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
15%
150 1054.62
10 Amylon 5
15% cooked in
2000 204.2
45.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
150 1054.62
DMSO
11 Amylon 5
15% Paraformalde-
1025 204.2
45.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
125 1054.62
hyde
12 Amylon 5
13% 40% caustic
2620 204.2
45.degree.
70 (NH.sub.4).sub.2 SO.sub.4
28%
150 1054.62
30 Na.sub.2 SO.sub.4
13 Amylon 5
13% 40% caustic
2620 204.2
45.degree.
90 (NH.sub.4).sub.2 SO.sub.4
28%
150 1054.62
10 H.sub.2 SO.sub.4
14 Corn 10% 15% caustic
2365 204.2
90.degree.
(NH.sub.4).sub.2 HPO.sub.4
Satd.
100 703.08
15 Waxy maize
10% cooked 2050 204.2
90.degree.
(NH.sub.4).sub.2 HPO.sub.4
Satd.
90 703.08
16 Corn 10% 15% caustic
2365 204.2
90.degree.
NH.sub.4 NH.sub.2 SO.sub.3
Satd.
75 703.08
17 Waxy maize
10% cooked 2050 204.2
90.degree.
NH.sub.4 NH.sub.2 SO.sub.3
Satd.
90 703.08
18 Amylon 5
13% 40% caustic
2620 102.1
45.degree.
(NH.sub.4)H.sub.2 PO.sub.4
Satd.
75 703.08
19 Corn 13% 15% caustic
2365 100 90.degree.
90 Na.sub.2 SO.sub.4
44%
75 703.08
10 (NH.sub.4).sub.2 SO.sub.4
3 H.sub.2 SO.sub.4
20 Starch blend
10% 40% caustic
2350 204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
95 703.08
containing 55%
amylopectin.sup.(2)
21 Oxidized corn
10% cooked 27 204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
75 356.54
starch
22 Acid-converted
5% cooked 9050 204.2
90.degree.
(NH.sub.4).sub.2 SO.sub.4
44%
150 1406.16
sulfo-succinated
corn starch
__________________________________________________________________________
.sup.(1) A hybrid corn starch containing approximately 52% amylose
(available from National Starch and Chemical Corporation).
.sup.(2) Mixture of 58% corn starch and 42% of a hybrid starch containing
70% amylose so as to obtain a blended starch product containing 55%
amylopectin.
TABLE II
______________________________________
Velocity
Example ratio Avg. Fiber Diameter
No. Angle of Entry
(salt/starch)
(microns)
______________________________________
23 0.degree. --.sup.(3) 138
24 45.degree. 8.9 73
25 90.degree. 6.99 85
26 180.degree. 0.15 565
______________________________________
.sup.(3) Meaningless due to inherent nature of countercurrent feed.
The resulting fibers varied in diameter (width) as shown in the table. The
cross-sectional configuration also varied with the roundest fiber being
formed at the 180.degree. entry and the flattest at 90.degree. entry.
EXAMPLE 27
Two starch dispersions were prepared at 10% solids: one from corn starch
(using 15% caustic) and another from waxy maize starch using the methods
described in Example 1-22. The dispersions were introduced into eight salt
blend solutions prepared at 44% solids and consisting of 90 parts ammonium
sulfate and 10 parts of one of the following salts: sodium sulfate,
ammonium bisulfite, ammonium persulfate, ammonium nitrite, ammonium
carbonate, ammonium bicarbonate, ammonium bromide, ammonium oxalate,
sodium chloride and potassium sulfate.
Satisfactory water-insensitive starch fibers were produced in all cases.
EXAMPLE 28
Using the basic procedure outlined in Example 1, a slurry was prepared from
waxy maize starch at 15% solids which was heated to 96.degree. C. until a
state of colloidal dispersion was obtained.
A pigment dispersion was separately prepared with equal parts of Sb.sub.2
O.sub.3 and dry vinyl chloride powder which were wetted in water using
1.5% pigment dispersant such that the total solids were 65%.
The pigment dispersion was then added to the previously prepared and cooled
starch dispersion so that there were equal dry parts of each component and
the final solids level was 24.4%, by weight.
The mix | | |
