Note: Descriptions are shown in the official language in which they were submitted.
Background of the Invention
This invention relates generally to a method ~or
continuously slurrylng adhesive solids ln an aqueous medlum,
cooking and cuttlng the slurry wlth an alkali cutting agent
so as to disperse the solids and thereby create a homogenous
water soluble adhesive for use as a coating binder.
In the past it has always been advantageous to
purchase coating lngredients in dry form because of con-
siderable savings on freight and energy. Previously, however,
the manufacturer of the coatlng adhesive would prepare ~he
formulatlon onsight in a batch-wise system. The dry powder
was added to water with agitation and heated ln a steam ~acketed
vessel or by sparglng steam dlrectly into the slurry. There ~as
a wetting-in period of approximately 5 minutes. At the end of
the wet-in period, a suitable alkali was added to the slurry and
the temperature of the mixture was ad~usted to between 140 and
160F. while the slurry was mixed for approximately 30 minutes.
There were several drawbacks to that method. Clearly, it was
cumbersome and time consuming, but more importantly the method
permltted manufacture of an adhesive which was limited to no
more than 14 to 18% solids. A large reaction vessel was essen-
tial, and an unduly long heatlng period was necessary, accurate
and reproducible mixtures were infrequent and an energy demand
was placed upon the batch system ln which the reaction took
place.
In accordance with this lnvention, lt is possible
to ellminate the manual batch-wise operations. It is also
posslble to accurately reproduce the mixtures on a contlnuous
basls.
Summary of the InventiGn
In one broad aspect, the invention comprehends
an improved method for preparing water soluble
adhesives, which method comprises the steps of heating
a continuous flow of water to a predetermined -temperature
relative to cooking adhesive solids -to be added,
subjecting the flow to a venturi flow pattexn, adding
through the venturi into the heated flowing water
; an anti-foaming agent at a rate of from .01% to 5%
by weight of adhesive solids, subjecting the flowing
water to vortex flow mixing conditions, and mixing
adhesive solids to be rendered water soluble, the
mixing being accomplished at the point of the vortex
flow mixing to provide a solids level in the water of
between about 5 to 25% by weight. Additional heat,
if necessary, may be provided to promote cooking of the
added adhesive solids. The method then includes
injecting from about .01 to .04 lbs. of an aqueous
alkali solution/lbs. of H20, the alkali solution
serving to adjust the pH of the solution to greater than
8.5, and finally subjecting the flow to a static mixing
action.
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Descrlptlon of the Drawing
_
Flg. 1 is a flow dlagram of the process Or this
invention.
Detailed Descrlption of the Preferred Embodim _
Re~errlng now to Flgure 1, ln accordance with the
present invention, water is contlnuously heated (1) to pro~rid~
a temperature between 32F. and 212F., usually at a minimum -
Or at least 130F. and preferably 160~F. The temperature must
be sufficiently high to cook the adhesive solids, preferably
protein. By "cooking" the solids one means ellmlnatlng small
: gell particles. Nevertheless, excessive heatlng must be avolded
: to prevent vaporization Or the water~ vapor lock in the product
pump and interruptions in the flow pattern.
The water is then sub;ected to a venturl (2) rlow
pattern as for example, through an inducer where an anti-foam
agent is added at a rate of from about 0.01% to 5% by welght,
based upon the dry weight of the adheslve solids. The antl-foam
may be, for example, any of the commerclal llquld materlal.
:
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Other additi~es which serve to modiry various characterlstics
of the adhesive may be added in thls same fashion. The
anti-roam and/or other addltives may or may not be necessary
dependlng upon desired end use. Although the venturi flow
addltlon is preferred, direct injection into the system wi-thout
a venturl is acceptable.
The flow is sub~ected to vortex flow mixlng (3) as
ror example, through a Tri-Blender~ at which point the adhesive
solids are added to provide a solids level, in the water, of
between about 5 and 25% by welght o~ water, pre~erably 20%
by weight 3 ( . 05 to .25 lbs/adhesive sollds/lb. H20). The adhe-
sive sollds are preferably proteln, such as for example,
hydrolyzed soy proteln isolate and casein. AIso~ starch may be
utllized. The sollds should be ground into rree-rlowing form
and o~ fairly consistent bulk density for most effectlve resul~s.
It is Or note that lf starch is utilixed, an additional heating
means will be employed downstream from the point at whlch the
starch is added. Thls is because the starch must be cooked at
a temperature of at least 190F. but if the system is that hot
prior to starch addltlon~ there ls a danger Or vapor lock in
the vortex flow mixing the stage of the system.
By ~ortex flow mlxing it is meant that the protein
and water are admixed with agitation and they come together in
a vortex creating a more homogeneou~ mixture.
An alkali solution such as NH40H is dlrectly in~ected
at (4) at a rate Or from about .01 to .04 lbs/lb H20. The
precise rate ~ill vary depending upon the particu'ar alXali, its
- burrering capacity and the partlcular characterlstlcs desired.
Provlded that a pH Or from about 8.5 to 10.0 is obtalned a
sultable cutting actlon will occur. By cutting action it is
meant that the lnsoluble protein wlll become solubl~. Typlcal
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examples Or alkall are NH40H and NaOH. It is partlcularly
preferred to use NH40H because there is little residual salt
left in the coating.
The product pump (5) delive~s the desired flow rate
which is from about 24 to 26 gallons/minute. There is a
static mixer t7) employed downstream from the pump in order to
completely intersperse the alkali throughout the slurry thus
assuring a homogeneous reaction.
The various ingredient streams of this process may
be fitted with a series of interlocking valves that are
automatically operated ~n sequence and at predetermined intervals
at (6). This permits automatic and continuous preparation of
the proteinaceous adhesive.
The following Example will lllustrate the operation
of this invention.
Example I
Water is pumped through a heat exchanger at 19.3
gallons/minute. Then 125 psi steam is used to heat the water
to 160F. which takes 100 BTU/# of the water. Anti-foam is
metered into the water stream at a rate of 120 ml~min. Soy
protein adhesive solids are metered into a Tri-Blender~ at a
rate of 40#/min. on a 90% dry basis as the heated water stream
containing anti-foam passes through the Tri-Blender0. Ammonium
hydroxide is added at a rate of .8 gal/mln. to adjust the pH
to between 9.2 and 9.6. The produc~ has a solids level of about
20%.
Having thus having described the above invention with
reference to a specific example it is intended to include all
reasonable equivalents and modiflcations within the scope of the
present Claims.
