Note: Descriptions are shown in the official language in which they were submitted.
BACICG_OU~ O~_T~-IE IN~-rrIoN
: 5 Field of the Invention
This invention pertains to compositions of matter
useful as laundry sour products.
Descri~ion of the Prior Art
Numerous steps in the processing of textiles involve
contacting the textiles with various chemical compounds such as
bleaching, dyeing, and washing compounds. At the conclusion of
each step it is necessary that alkaline residues be removed from
the textile fabrics before the next processing step. So, too,
in laundering operations it has been found desirable to remove
the residual soaps or synthetic detergents remaining on the
laundered fabrics. Residue removal in both circumstances is
commonly accomplished by contacting the fabrics with an aqueous
solution of a composition exhibiting an acid r~action. These
compositions are hereinafter referred to as laundry sours. Over
20 the years, numerous acid materials have been used in compound- :
ing laundry sourS . Today,~the most commvnly used materials are
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sodium silicofluoride (Na2Si F6), sodium bi~luoride (sodium acid
fluoride, NaF-~-lF), and mixtures of the two. A common mixture
will contain 75% by weight sodium silicofluoride and 25% by
weight sodium bifluoride. In addition to the fluoride salts,
additives are sometimes used in sour compositions. Very cor~mon
additives are optical bleaches wllich are referred to in the art
as brighteners. A common brightener level is ~1% of the total
fluoride salt content.
While the above-described fluoride salt mixtures ade-
~uately perform the desired souring function, com~ercial ex-
perience has demonstrated that the mixtures exhibit undesirable
caking properties. m at is, when the mixtures are stored in
drums under unfavorable conditions of temperature and humidity,
such as are frequently encountered in textile processing plants
and co~nercial laundries, they exhibit a tendency to form hard
lumps, cakes,and chunks. This caking tendency, while not inter-
fering with the souring action once the product has been added to
the souring bath, causes inconvenience to the oFerators of the
textile plants and the commercial laundries in that the em-
ployees of these establishments must spend time breaking upthe cakes and lumps in order to remove the ~aundry sour from
its container and in order to dissolve the composition in the
souring bath. There has long ~een felt a need in the textile
processing and commercial laundry industries for a laundry sour
25 composition which will be available at the time of its use in
the form of a free flowing powder. Certain additives, such as
magnesium oxide, have been proposed for reducing the caXiny
tendency of laundry sours, but deficiencies in terms of per-
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formance and cost have rendered them less than completelysatisfactory.
It is an object of this invention to provide
a fluoride-containing laundry sou:r which remains free
flowing even after storage for extended periods in drums
under adverse conditions of tempe.rature and humidity.
SUMMARY OF THE INVENTION
According to the present invention there is
provided a non-caking laundry sour composition which
comprises sodium silicofluoride; sodium bifluoride; anhydrous
calcium sulfate; wherein the weight ratio of sodium silico-
fluoride to sodium bifluoride is 3:1 and wherein the
calcium sulfate is present at from 0.3 to 1% by weight of
; the total fluoride salt content.
DESCRIPTION OF THE PREFERRED EMBODIMENTS .
The fluoride salt-containing laundry sour ~ .
contemplated for use in this invention is composed of one
or more of the common water-soluble fluoride salts used
in laundry sours. Examples of such fluoride salts are :
sodium silicofluoride, zinc silicofluoride, ammonium
: silicofluoride, sodium bifluoride, and ammonium bifluoride.
A preferred laundry sour composition is composed of
sodium silicofluoride and sodium bifluoride in a weight
ratio of sodium silicofluoride to sodium bifluoride of
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1:1 to 5:1. A highly preferred laundry sour is composed of
sodium silicofluoride and sodium bifluoride in a weiyht ratio
of 3:10
While anhydrous calcium sulfate has been found to be
the most highly preferred anti-caking material for addition to
fluoride salt-containing laundry ~ours, other chemicals have
been shown to be effective anti-caking agents. rTIIese other
materials are anhydrous calcium chloride, anhydrous magnesiuln
sulfate, anhydrous sodium dibasic phosphate and calcium tri-
basic phosphate. Each of these materials is used at levels offrom 0.1 to 1.5% by weight of the total fluoride salt comp~nent
of the laundry sour composition, preferably at levels of from
0.3 to l.~/o by weiyht of the total fluoride salt component.
Brighteners, such as disodium 4,4'~bis(4-morpholino-
~-anilino-s-triazine-2-yl-amino)~2,2'-stilbene disulfonate,
may optionally be used in the laundry sour at from 0.01 to
0.5% by weight of the total fluoride salts present. The pre-
ferred level of brightener is 0.1~ by weight of the total
fluoride salt present.
To maXe the non-caking laundry sours of this invention,
the dry, powdered ingredients are intimately blended by hand
or in a mechanical mixer such as a V-cone mixer or an intern-
ally baffled rotating drum mixer. In a preferred method of
making a preferred non-caking laundry sour (i.e. one con-
taining sodium silicofluoride and sodium bifluoride in a weight
ratio of 1:1 to 5:1) the appropriate amount of anti-caking
material is in~i~a~ely blended Witll the sodium bifluoride com-
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ponent and this mixtu,-e is then intimately b7ended ~itll the
sodiwn siJicofluoride component and 'che optiona] brightener,
if one is used.
The following examples illustrate thc use of this
invention, but are not to be construed as in any way limiting
the scope of the invention.
EX~MPLE I
One-half (0.5) pound sodium bifluoride and 0.01
pound powdered anhydrous calcium sulfatewere placed in an
internally baffled rotating drum mixing apparatus. The
apparatus was started and allowed to run for two minutes
until an intimate mixture o the bifluoride and the calcium
sulfate was obtained, The mixer was stopped and one and
one-half (1.5) pounds sodium silicofluoride and 0.002 pound
brightener were added. ~he apparatus was started and allowed
to run 6 minutes until an intimate mixture of the ingredients
was obtained. The resulting product was free-flowing even
after storage at 90F. and 80% relative humidity for 5 days
and it adequately performed its assigned souring task.
EXAMPLE II
The procedure of Example I is repeated except that
in successive batches o souring composition, the calcium sulfate
is replaced in turn by 0.01 pound of anhydrous calcium chloride,
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0.01 pound anhydrous magnesium sul~ate, 0.01 pound anhydrous
sodium dibasic phosphate, and 0.01 pound calcium tribasic
phosphate. In each case, a non-caklng laundry sour compo-
sition is obtained.
EXAMPLE III
An anti-caking souring composition is prepared as
in Example I except that 0.03 pound anhydrous calcium sulfate
is mixed with the sodium bifluoride. ~s in Example I, the
mixture exhibits a lack of caking on storage under adverse
conditions of temperature and humidity and successfully and
adequately performs the desired souring task.
EXAMPLE IV
Seventy-five (75) pounds of sodium silicofluoride
(Na2Si F6) and twenty-five (25) pounds of sodium bifluoride
(NaF-~F) are formed into an intimate mixture by blending the
powdered materials. During the blending operation, 0.1 pound
of brightener is added to the mixing fluoride salts. After
the brightener is added, 0.5 pound powdered, anhydrous calcium
sul~ate is added to the fluoride salt composition. The total
laundry sour composition is blended until a uniform, intimate
mixture is obtained. This souring composition demonstrates
excellent anti-caking properties and adequately performs its
souring ~unction.
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I.aundry sour compositiolls prepared according to this
invention ean contain from about 98.52% to about 99.90% by
weight of a water-soluble fluoride salt seleeted from the group
eonsisting of sodium silieofluoride, sodium bifluoride and
mixtures thereof, and from about 0.10% to about 1.48% by weight
of an anti-eaking agent selected from the group consisting of
anhydrous ealcium sulfate, anhydrous caleium ehloride, anhy-
drous magnesium sulfate, anhydrous sodium dibasie phosphate
and ealeium tribasie phosphate. In a preferred embodiment,
the laundry sour would eontain from about 99.01% to about 99.70/O
by weight fluoride salt and from about 0.30/O to about 0.99% by
weight anti-eaking agent.
WHAT IS CLAIMED IS:
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