* GB786094 (A) Description: GB786094 (A) ? 1957-11-13 Phosphate compositions, their production and use Description of GB786094 (A) A high quality text as facsimile in your desired language may be available amongst the following family members: DE1009750 (B) FR1132395 (A) DE1009750 (B) FR1132395 (A) less Translate this text into Tooltip [81][(1)__Select language] Translate this text into The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes. PATENT SPECIFICATION 786,094 Date of Application and filing Complete Specification: April 18, 1955. No 11075155. Application made in United States of America on April 16 1954. Complete Specification Published: Nov 13, 1957. Index at acceptance -Classes 1 ( 3), A 1 (D 37: G 1 D 37:050 D 37); and 919 D 2 (F:H:S). International Classifcation:-CO 1 b, C 11 d. COMPLETE SPECIFICATION Phosphate Compositions, their Production and Use WC, MONSANTO CHEMICAL COMPANY, a Corporation organized under the Laws of the State of Delaware, United States of America, of 1700 South Second Street, City of St Louis, State of Missouri, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be
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* GB786094 (A)
Description: GB786094 (A) ? 1957-11-13
Phosphate compositions, their production and use
Description of GB786094 (A)
A high quality text as facsimile in your desired language may be available
amongst the following family members:
DE1009750 (B) FR1132395 (A)
DE1009750 (B) FR1132395 (A) less
Translate this text into Tooltip
[81][(1)__Select language]
Translate this text into
The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
PATENT SPECIFICATION
786,094 Date of Application and filing Complete Specification: April
18, 1955.
No 11075155.
Application made in United States of America on April 16 1954.
Complete Specification Published: Nov 13, 1957.
Index at acceptance -Classes 1 ( 3), A 1 (D 37: G 1 D 37:050 D 37);
and 919 D 2 (F:H:S).
International Classifcation:-CO 1 b, C 11 d.
COMPLETE SPECIFICATION
Phosphate Compositions, their Production and Use WC, MONSANTO CHEMICAL
COMPANY, a Corporation organized under the Laws of the State of
Delaware, United States of America, of 1700 South Second Street, City
of St Louis, State of Missouri, United States of America, do hereby
declare the invention, for which we pray that a patent may be granted
to us, and the method by which it is to be performed, to be
particularly described in and by the following statement: -
This invention relates to alkali metal phosphate compositions and more
specifically to alkali metal tripolyphosphate and pyrophosphate
compositions which have a relatively low rate of precipitation or
crystallization from aqueous solution The invention also relates to
methods for producing the aforementioned phosphate compositions.
The invention also relates to the control of the rate of precipitation
or crystallization of such phosphates from aqueous solutions and is
particularly useful in connection with the manufacture of detergent
compositions by spray drying techniques.
Many detergent compositions, and especially those of the dry granular
type, such as those intended for home laundry use, are mafde up from a
plurality of components including a so-called "active" ingredient,
such as an alkali metal salt of a sulphonated alkylated aromatic
hydrocarbon or a condensation product of ethylene oxide with a long
chain alkyl alcohol or mercaptan, a predominant proportion of a
so-called "builder" such as sodium tripolyphosphate or tetrasodium
pyrophosphate, and a small amount of a corrosion inhibitor such as an
inorganic silicate, e g, sodium metasilicate.
One of the problems in formulating a satisfactory and commercially
useful granular mixture of several dry ingredients is to obtain a
satisfactorily uniform distribution of each of the separate
ingredients throughout the bulk of the mixture: failure to obtain this
will increase the probability that lPrice 3/61 small portions
withdrawn from the bulk of the mixture will have a composition
substantially different from the overall composition of the total bulk
Another problem in the formulation of such mixtures is to obtain a 50
satisfactorily uniform particle size distribution of the ingredients:
failure to obtain this will give rise to an automatic classification
process whereby the coarse and fine particles will tend to separate
from each other during 55 the transportation and handling of the
packaged or bulk solids.
One way in which the aforementioned difficulties are overcome, or at
least minimized, is by spray drying In such a pro 60 cess a slurry of
the solids in water is broken up into relatively uniformly sized
droplets by atomizing the slurry The droplets are then passed into or
through a heated zone wherein the water is evaporated from each 65 of
the droplets, leaving discrete dry granular particles or agglomerates
By proper control of the conditions under which the spray drying is
carried out, it is possible to obtain a reasonably uniform
distribution of particle 70 sizes, with each of the individual
particles containing approximately the same proportions of the various
components.
One of the factors which is particularly important in the control of a
spray drying 75 process is that of the viscosity, or consistency, of
the slurry which is to be atomized.
If the slurry is too thick or viscous, proper atomization thereof is
very, difficult In such a case the fluidity of the slurry can be 80
increased by increasing the amount of water in the slurry, but an
increase therein is undesirable since a large quantity of slurry must
be handled, and a larger quantity of water must be evaporated, for a
given output 85 of detergent composition Thus, it is very advantageous
to have the solid content of the slurry as high as possible while
still maintaining the required degree of fluidity for adequate
atomization of the slurry 90 C",; 786,094 As indicated above, sodium
tripolyphosphate and/or tetrasodium pyrophosphate are often used as
predominant components of granular detergent compositions prepared by
spray drying processes The commercial tripolyphosphate and
pyrophosphate utilized in such processes are usually in anhydrous form
When these anhydrous phosphates are made into an aqueous slurry, there
is a marked tendency for the slurry to increase rapidly in
consistency, and the slurry may be transformed into a completely
non-fluid mass This increase in viscosity or loss of fluidity is at
least partially caused by the is reduction in the free water content
of the slurry because of the hydration of the anhydrous phosphates and
may also be accentuated by the manner in which crystal growth of the
hydrates occurs As a consequence thereof, in order to maintain the
slurry in a satisfactory fluid state, it is necessary either to
increase the amount of water in the slurry or to find a way to prevent
or delay the precipitation or crystallization of the hydrates of these
phosphates.
Accordingly, objects of the present invention are to decrease the rate
of crystallization of certain phosphates from aqueous solutions
thereof, to provide a novel phosphate composition which is
particularly useful in the formation of high fluidity slurries
suitable for spray drying operations and to provide suitable methods
for making such phosphate compositions An additional object is to
provide a method for forming slurries of phosphates which are highly
suitable for spray drying processes.
According to the present invention there is provided a phosphate
composition comprising an anhydrous alkali metal phosphate having a
molar ration M 20/P 20 O, in which M is an alkali metal, or from 5/3
to 2 and a water-soluble linear polymeric phosphate having more than
three phosphorus atoms in its linear chain, the proportion of the
latter not exceeding 10 % of the total dry weight of the mixed
phosphates.
It has also been found that a very suitable phosphate composition can
be prepared by intimately admixing a comminuted watersoluble linear
polymeric phosphate of the above kind with a granular or powdered
anhydrous alkali metal phosphate, the proportion of the former not
exceeding 10 % 1, of the total dry weight of the mixed phosphates It
has also been found that such phosphate compositions are particularly
useful in the preparation of detergent slurries suitable for spray
drying to forn granular detergent compositions.
Typical of the linear polymeric phosphates suitable for use in the
various aspects of the present invention are the sodium phosphate
glasses, i e, the amorphous compositions having Na 2 OIP RO molar
ratios between 1 and 1 67 As has been pointed out in the literature
(see, for example, Van Wazer, Journal of the American Chemical
Society, volume 72, pp 644-647 and 647-655 ( 1950)), these phosphate
glasses are mixtures of 70 water-soluble, straight-chain, polymeric
materials having a chain consisting of alternating atoms of oxygen and
phosphorus.
These mixtures of linear polymeric phosphates can be characterized in
terms of an 75 average chain length, h The term "chain length", as
applied to these straight chain polymeric phosphates, refers to the
number of phosphorus atoms in the straight chain polymer 80 It is also
pointed out by Van Wazer that the average chain length of the mixture
of polymers in ia sodium phosphate glass is primarily a function of
the ratio of Na 2 O/P 20, in the melt from which the glass 85 was
formed The predominant polymer in such a mixture has a chain length
equal to the whole number most nearly approaching the value of the
average chain length The proportions of the other chain length poly-90
mers in the mixture become progressively smaller as the chain length
increases or decreases from the average chain length.
The average chain length of the glasses becomes increasingly greater
as the ratio of 95 Na O/P,O decreases ranging from a chain length of
three when the Na,OIP O ratio equals 5/3 to a chain length of several
thousands as the ratio of Na,O/P DO, approaches unity 100 As
previously indicated, the linear polymers suitable for use according
to the present invention are those having a chain length greater than
3 As the len Oth of the chain increases, the polymers become more
effec 105 tive for the purposes of the present invention Thus,
polymers having a chain length of 4 aremoreeffectivethan those having
chain lengths of less than 4 Likewise, polymers having a chain length
of 5 are more effective 110 than those having a chain length of 4 and
so on A preferred class of linear polymeric phosphates are those
having an average chain length greater than 10 While the effectiveness
increases as the chain length 115 increases, the rate of increase of
effectiveness with respect to increase in chain leneth decreases as
the chain length increases.
Examples of particularly desirable linear polymeric phosphates are the
commercially 120 available sodium phosphate glasses having molar
ratios of Na,OIP 1 RO, of substantially 1.1, substantially 1 4 and
substantially 1 55.
We have stressed the importance of sodium phosphate glasses in the
practice of 125 the present invention because they are very well known
and more widely available than some of the other sources of linear
polymeric phosphate ions However, it should be understood that any
material which can 130 786,094 supply the polymeric phosphate ion is a
suitable source Examples of other suitable materials are Kurrol's salt
(a water-soluble, crystalline linear polymeric potassium
metaphosphate), lithium phosphates having a molar ratio of Li 2 O/P O,
between 1 and 13, linear polymeric ammonium phosphates formed either
by replacing alkali metal ions of polymeric phosphates with ammonium
ions or by reaction of ammonia and phosphorus pentoxide (with or
without water) Also satisfactory are the acids corresponding to the
foregoing salts In order to affect the rate of crystallization of the
tripoly and pyrophosphates, it is necessary that the linear polymeric
phosphate ions be in solutioh Consequently, any salts which are used
as a source of such ions must be soluble in the tripoly or
pyrophosphate solution, at least to the extent of the minimum
effective concentration of the ion.
As indicated above, the effectiveness of the linear polymeric
phosphates increases with increasing chain length of the phosphates
When these linear polymeric phosphates are utilized with
tripolyphosphates, the effectiveness also varies somewhat with the
crystalline form of the tripolyphosphate.
As is well known, sodium tripolyphosphate exists in two different
crystalline formsone known as the high temperature form (or Form V),
and the other known as the low temperature form (or Form II) A
preferred embodiment of the present invention is the use of the
above-described polymeric phosphates with sodium tripolyphosphate-II,
or with the mixtures of Form I and Form II containing more than 75 %
by weight of the Form II material Best results are obtained when
using;mixdtures containing less than % by weight of Form I, or even
less than % by weight of Form I.
Because of -the marked change in effectiveness of the polymeric
phosphates with respect to both the chain length of the polymers and
the crystalline form of the phosphates to which the polymers are
added, the minimum effective concentration of the polymeric phosphates
will vary over a rather wide range In general, at least 0 01 % by
weight (based upon the total dry weight of phosphates present), and
preferably at least 0.1 % by weight, should be utilized In extreme
cases, such as when using the short chain polymers in tripolyphosphate
mixtures containing relatively large proportions of the Form I
modification, as much as 1 % by weight or more of the polymeric
phosphate may be required More than 10 % will not be required, and
under most circumstances %O will be more than adequate.
As indicated above, a preferred embodiment of the present invention is
the preparation of the alkali metal tripolyphosphate or pyrophosphate
compositions into which the water-soluble linear polymeric phosphates
have already been incorporated One of the simplest ways to prepare
such a composition is by fine grinding or otherwise comminuting the
polymeric phosphate and intimately 70 intermixing it with the granular
or powdered alkali metal tripolyphosphate or pyrophosphate in the
requisite proportions.
Another way to form such a composition with the polymeric phosphate
intimately 75 and uniformly distributed throughout the bulk of the
alkali metal tripolyphosphate or pyrophosphate is to form a solution
of the polymeric phosphate in a volatile solvent, such as water or an
alcohol-water mixture,80 and then to spray the solution on to or into
a heated bed of the other phosphate The solvent is evaporated 'from
the bed, thereby precipitating the polymeric phosphate within the bed
of tripoly or pyrophosphate It is 85 particularly advantageous to
maintain the temperature of the bed of phosphate above the boiling
point of the solvent in which the polymeric phosphate is dissolved In
this way, the solvent is evaporated very 90 quickly upon contact with
the phosphate bed, and there is less tendency for the solvent to
dissolve any of the tripoly or nyrophosphate and cause clumping or
agglomerating.
Another way of preparing suitable phos 95 phate compositions
containing small amounts of linearly polymeric phosphates is by
exposing the alkali metal 'tripolyphosphate to an elevated temperature
for a relatively short period of time in order to fuse 100 a small
amount of the material on the surface of the tripolyphosphate
particles The fusion of tripolyphosphate results in the formation of
solid pyrophosphate and molten linearly polymeric phosphates having
105 an average chain length somewhat above 3.
While equilibrium cooling of the fused tripolyphosphate would result
in the reconversion of the pyrophosphate and linear polymers to
tripolyphosphate, a relatively 110 rapid cooling will trap the linear
polymeric materials in a non-equilibrium glassy state, thus giving the
desired tripolyphosphate composition containing a small amount of the
linear polymeric phosphate of chain 115 length longer than 3.
The phosphate compositions into which the linear polymeric phosphates
have been incorporated are utilized in the preparation of crutcher
mixes (or slurries) for spray 120 drying in substantially the same
general manner that the phosphate builders have been utilized in the
past However, a higher concentration of solids can be utilized in
slurries of the present phosphate composi 125 tions without increasing
the viscosity of the slurry, or alternatively, the viscosity of the
slurry can be markedly decreased without decreasing the concentration
of solids in the slurry 130 786,094 As an alternative to incorporating
the polymeric additives into the slurry as an integral component of a
phosphate builder composition, the additives can be incorporated into
the aqueous slurries independently of the phosphate "builder"
addition.
If added independently, however, the linear polymeric phosphates
should be added to the slurry prior to, or at least at substantially
the same time as, the phosphate builder is added If added much later,
substantial precipitation and crystallization of the hydrated
phosphate will have taken place before the linear polymeric material
has an opportunity to delay such crystallization.
The term "linear" as us-ed herein with respect to the polymeric
phosphates, includes branched as well as "normal" chain phosphate
polymers, but excludes the cyclic phosphates such as the
trimetaphosphates.
The ammonium polyphosphates, and especially those in which oxygen
atoms have been replaced by imido nitrogen atoms, are examples of
linear polyphosphates believed to have branched chains.
The following examples illustrate the nature of the invention and the
manner in which it may be performed.
EXAMPLE 1
Fifty grams of 95 % glycerine and 50 g.
of powdered sodium tripolyphosphate ( 2.4 o by weight of Form I, the
remainder Form II) were thoroughly intermixed in a ml tall beaker
Twenty-five millilitres of water was then added to the mixture and vi
35 orously stirredforabout 2 minutes Theresulting mixture was then
allowed to stand for about minutes After this time the beaker was
inverted, but the consistency of the mixture had increased to such an
extent that only 40 a few drops of liquid ran out of the beaker.
A parallel test was carried out in the same manner, except that 0 5 g
of a glassy sodium polyphosphate having an average chain length of
substantially 5 5 was dissolved in 45 ml of water prior to inixina
with the glycerine-sodium tripolvphosphate mixture.
In this latter case, the enti-re slurry was readily poured from the
beaker after 30 minutes standing 50 EXAMPLE 2
The procedure of Example 1 was repeated.
except that various water-soluble linearly polymeric sodium phosphates
in finely 55 divided form were physically admixed with the sodium
tripolyphosnhate prior to incorporation into the glycerine The results
of these tests are sumnmarized in the following table: 60
SODIUM PHOSPHATE GLASS Average Concentration chain inr wt% length (ii)