AMINOMETHYLENEPHOSPHONATE-COATED GRANULES

GRANULES A REVETEMENT D'AMINOMETHYLENEPHOSPHONATE

English Abstract

AMINOMETHYLENEPHOSPHONATE-COATED GRANULES
ABSTRACT OF THE DISCLOSURE
Aminomethylenephosphonate-coated granules
of substantially water-insoluble silicate having
improved stability in the presence of peroxygen
compounds. Such coatings can comprise alkali metal
aminomethylenephosphonate of the formula:
<IMG>
where each R is H, CH2PO3H2 or CH2PO3HM or CH2PO3M2;
where M is an alkali metal; and n is 0 or an integer,
preferably an integer of from 1 to 4. The coatings
are substantially free of peroxygen compounds and
peroxy compound precursors.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Aminomethylenephosphonate-coated
granules of a substantially water-insoluble silicate
wherein said granules have a coating consisting
essentially of aminomethylenephosphonates.
2. The granules of claim 1 wherein a major
component of said aminomethylenephosphonates are
alkali metal salts of aminomethylenephosphonic acid
having the formula:
<IMG>
wherein R is H, CH2PO3H2, CH2PO3HM or CH2PO3M2; M
is an alkali metal; and n is 0 or an integer from 1-4.
3. The granules of claim 2 wherein an
average of at least one-half of R is CH2PO3HM or
CH2PO3M2.
4. The granules of claim 3 wherein said
silicate is an aluminosilicate having a layered sheet
structure.
5. The granules of claim 4 wherein said
aluminosilicate is a kaolinite or smectite clay.
6. The granules of claim 5 further includ-
ing an inorganic alkali metal salt.
7. The granules of claim 6 wherein said
salt is sodium sulphate.
8. The granules of claim 5 wherein said
aminomethylene phosphonate is a sodium salt and n is 0
or 1.
9. The granules of claim 8 wherein ratio of
aminomethylenephosphonate to silicate is on a dry
weight basis in the range of about 1:1 to about 1:4.

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10. The granules of claim 9 wherein the
average particle size is in the range of about 50 to
about 600 micrometers.
11. Substantially water-insoluble granular
silicate having a coating comprising aminomethylene-
phosphonate, wherein said coating is essentially
devoid of peroxygen compounds and peroxygen compound
precursors.
12. Granular silicate of claim 11 wherein
said coating comprises alkali metal salts of amino-
methylenephosphonic acid.
13. Granular silicate of claim 12 wherein
said salts are of the formula:
<IMG>
wherein R is H, Ch2PO3H2, Ch2PO3HM or CH2PO3M2; M is
an alkali metal and n is 0 or an integer from 1 to 4.
14. Granular silicate of claim 13 wherein an
average of at least one-half of R is CH2PO3HM or
CH2PO3M2.
15. Granular silicate of claim 14 wherein
said silicate is an aluminosilicate having a layered
sheet structure.
16. Granular silicate of claim 15 wherein
said aluminosilicate is kaolinite or smectite clay.
17. Granular silicate of claim 16 further
comprising sodium sulphate.
18. Granular silicate of claim 15 wherein
the ratio of aminomethylenephosphonate to silicate is
on a dry weight basis in the range of about 1:1 to
about 1:4.

19. Granular silicate of claim 18 having an average
particle size in the range of about 50 to about 600
micrometers.
20. A dry detergent mixture comprising peroxygen
compounds, surfactants and granular silicates according
to claim 11.
21. Aminomethylenephosphonate-coated granules of a
substantially water-insoluble aluminosilicate having a
layered sheet structure wherein said granules have a
coating essentially devoid of peroxygen compounds and
peroxygen compound precursors consisting essentially of
aminomethylenephosphonates having as a major component
alkali metal salts of aminomethylenephosphonic acid of
the formula
<IMG>
where R is H, CH2PO3H2, CH2PO3HM or CH2PO3M2; M is
alkali metal; and n is 0 or an integer from 1-4; and the
ratio on a dry basis of aminomethylenephosphonate to
silicate is from 1:0.5 to 1:10.
22. The granules of claim 21 wherein an average of
at least one-half of R is CH2PO3HM or CH2PO3M2.
23. The granules of claim 22 wherein said alumino-
silicate is a kaolinite or smectite clay.
24. The granules of claim 23 further including an
inorganic alkali metal salt.
25. The granules of claim 24 wherein said salt is
sodium sulphate.
26. The granules of claim 23 wherein said amino-
methylenephosphonate is a sodium salt and n is 0 or 1.
27. The granules of claim 26 wherein ratio of
aminomethylenephosphonate to silicate is on a dry weight
basis in the range of about 1:1 to about 1:4.
28. The granules of claim 27 wherein the average
particle size is in the range of about 50 to about 600
13

micrometers.
29. Substantially water-insoluble granular alumino-
silicate having a layered structure and having a coat-
ing comprising aminomethylenephosphonate having as a
major component alkali metal salts of aminomethylene-
phosphonic acid of the formula
<IMG>
wherein R is H, CH2PO3H2, CH2PO3HM or CH2PO3M2; M is an
alkali metal and n is 0 or an integer from 1-4, which
coating is essentially devoid of peroxygen compounds and
perGxygen compound precursors, and the ratio on a dry
basis of aminomethylenephosphonate to silicate is from
1:0.5 to 1:10.
30. Granular silicate of claim 29 wherein said
coating comprises alkali metal salts of aminomethylene-
phosphonic acid.
31. Granular silicate of claim 29 wherein an
average of at least one-half of R is CH2PO3HM or
CH2PO3M2 .
32. Granular silicate of claim 31 wherein said
aluminosilicate is kaolinite or smectite clay.
33. Granular silicate of claim 32 further compri-
sing sodium sulphate.
34. Granular silicate of claim 29 wherein the ratio
of aminomethylenephosphonate to silicate is on a dry
weight basis in the range of about 1:1 to about 1:4.
35. Granular silicate of claim 34 having an average
particle size in the range of about 50 to about 600
micrometers.
36. A dry detergent mixture comprising peroxygen
compounds, surfactants and granular silicates according
to claim 29.
14

Description

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AMIN METHYLENEPHOSPHONATE-COATED GRANULES
This invention relates to stabilized amino-
methylenephosphonate compositions in the form of
powder or granules.
Various aminomethy:Lenephosphonic acids and
their ~ater-soluble salts are known materials having a
variety of uses including stabilization of peroxygen
compounds, e.g. by chelation of heavy metals such as
iron or copper which can activate peroxides, and
inhibition of scale in water-~treatment processes.
Certain of the aminomethylenephosphonic
acids are stable solids, but for many applications
their alkali metal salts (in which some or all of the
acidic hydrogen atoms of the phosphonic acid are
replaced by alkali metal ions) are more suitable.
Such alkali metal salts are not, in isolation, stable
solids, being highly hygroscopic or deliquescent and
they are therefore sold as aqueous solutions. For
certain uses, e.g. as components of dry detergent
compositions, a powder or granular form of such salts
would be advantageous. Moreover, the aminomethylene
phosphonates are generally adversely affected, i.e.
oxidized, by peroxygen compounds. Thus, the presence
in the compositions of the invention of peroxygen
materials which tend to generate such an environment
is undesirable.
SUM~ARY OF THE INVENTION
An object of this invention is to provide a
granular form of aminomethylenephosphonate, e.g. as an
alkali metal salt, which is resistant to oxidation by
peroxygen compounds.
This and other objects of this invention are
provided by aminomethylenephosphonate-coated granules
of a substantially water-insoluble silicate. Dry
detergent formulations comprising such granules are
also provided.
~. .

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DESCRIPTION OF T~ PREFERRED EMBODIMENTS
In certain aspects of this invention such
coating consists essentially of alkali metal salts of
aminomethylenephosphonic acid, e.g. of the formula:
R
N~CH2-CH2-N ~ R
R
R
where each R is H, CH2PO3H2, CH2PO3HM or CH2PO3M2;
where M is an alkali metal; and n is 0 or an integer,
preferably an integer of from 1 to 4. The water-
insoluble silicate granules can be a silicate or
aluminosilicate, preferably having a layered sheet
structure. The coating is preferably substantially
free of peroxygen compounds and peroxy compound
precursors.
Preferred aminomethylenephosphonates for use
in the coating of the granules of the present inven-
tion are the alkali metal salts, especially the sodium
salts, of ethylenediaminetetra~methylenephosphonic
acid) and of diethylenetriaminepenta(methylenephos-
phonic acid), and mixtures thereof. The alkali metal
salts can be made from the corresponding acids by
neutralization, or partial neutralization, with alkali
metal hydroxides. It is generally desirable for many
uses of the granules of this invention, e.g. in dry
detergents, that the pH of the granules (e.g. in
water3 be neutral or only slightly acidic. Generally
more than half, or an average of more than half, of
the R groups are mono- or di-alkali salts of methy-
lenephosphonic acid.
The commercially available aminomethylene-
phosphonic acids are usually mixtures having different
nu~bers of (methylenephGsphonic acid) groups. Thus
the major components of sodium salts prepared from a
commercial ethylenediaminepoly(methylenephosphonic

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3 43-21(6765)A
acid) are compounds in which the four R groups in the
above formula are all CEI2PO3Na2 or CH2P03HNa; but the
compounds in which three or two R groups are CH2P03Na2
or CH2PO3HNa (the other(s) being hydrogen or, as an
; 5 impurity, CH3) are also present. Preferably at least
80% of the R groups in the mixture are CH2P03Na2 or
CH2PO3HNa groups.
Similarly, in the diethylenetriamine deriva-
tives, the penta(methylenephosphonate) usually accounts
for from 60 to 80% of the total weight of the derivative,
the remainder being mostly the tri(methylenephosphonate)
with a small amount of the tetra(methylenephosphonate).
Preferably at least 65% of the R groups in the mixture
are CH2PO3~a or CH2PO3HNa groups.
The water-insoluble silicate can be an
aluminosilicate, preferably a clay, especially a clay
of the smectite or kaolinite type. The former include
al~ali and alkaline earth metal montmorillonites,
saponites and hectorites, and the latter include
kaolinite itself, calcined kaoline and metakaolin.
The water-insoluble silicate, including
aluminosilicate, preferably has an original average
particle size (as measured by sieve screening) within
the range of about 0.5 to about 50 micrometers; but in
the coated granules of the invention the particles are
generally agglomerated. Such coated granules of the
invention preferably are of an average particle size
of at least about 50 micrometers; in some cases a
preferred minimum mean particle size is about 150
micrometers; in other cases an optimum mean particle
size is often in the range of about 400 to about 500
micrometers; in most cases it is preferred that
particle size be no greater than about 600 micrometers.
In the granules of this invention, the ratio
on a dry weight basis of aminomethylenephosphonate
coating to silicate can, for example, range from about

7~
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1:0.5 to about 1:10, for instance from about 1:1 to
about 1:10, a preferred range being from 1:1 to 1:4,
more preferably from about 1:1.5 to about 1:4. It has
been observed that the storage stability of the
product improves as the amount of silicate increases,
up to a certain level beyond which no significant
further improvement occurs. This maximum effective
ratio varies according to the particular silicate
being used, but is often found to be between about 1:2
and about 1:3.
The coating of the granules of this invention
may contain additional ingredients, provided that such
ingredients have no adverse effects on the use for
which the granules are intended. A principal use
envisaged for the granules of the invention i~s as a
component of dry detergent formulations. If desired,
therefore, other ingredients conventionally included
in such detergent formulations (other than peroxygen
compounds and peroxy compound precursors as indicated
above) can be present in such coatings. These optional
other ingredients include surfactants, particularly
anionic and nonionic surfactants; various inorganic
alkali metal salts, for example carbonates, borates,
phosphates, polyphosphates, metaphosphates and sul~
phates; organic builders, for example nitrilotri-
acetates and polycarboxylates; and thickeners, for
example carboxymethylcellulose. The total amount of
any such additional ingredients is preferably not
greater than twice the amount of the silicate or
aluminosilicate component.
The granules of this invention are usually
prepared by spray-drying a slurry of the components at
a conventional spray-drying temperature, for example
within the range 200-350C, with conditions adjusted
to give the required particle size and moisture
content. The latter is desirably as low as possible.
The moisture content tends to increase slowly on

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storage, so that typically a commercial composition
may have a moisture content within the range of about
5-10 percent by weight.
In the following examples coated granules of
this invention were prepared by forming a slurry from
the components shown in the tables below with, if
necessary, sufficient water to give approximately 55%
by weight of solids in the slurry. The slurry was
then spray dried to provide coated granules of sub-
stantially water-insoluble silicate.
China clay, as usecl in the following e~amples,
describes a water-washed product, prepared from
hydrothermally modified granite found in southwest
England. It is mainly a hydrated aluminum silicate
with the approximate formula Al203~2SiO2~2H20, and
mineralogically it is composed of kaolinite with minor
amounts of micaceous minerals, felspar and quartz.
Westone and Bentonite A.S. are smectite clays supplied
by English China Clays.
EXAMPLE 1
A slurry, having the composition indicated
in Table 1, was spray dried to provide aminomethylene-
phosphonate-coated silicate granules. The spray-dried
coated granules comprised the sodium aminomethylene
~5 phosphonates, clay and sodium sulphate in the approxi-
mate proportions by weight 1.3:2:1.

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TABLE 1
Slurry Com~onent Weight Parts
Sodium salt of ethylenediaminetetra 27
~methylene phosphonic acid), mainly
pentasodium salt. 33% by weight
aqueous solution.
Sodium salt of diethylenetri- 54
aminepenta(methylenephosphonic
acid), mainly the heptasodium salt.
Approx. 33% by weight aqueous
solution.
China clay. 70% by weight slurry59
in water.
Anhydrous sodium sulphate. 20
EXAMPLE 2
A slurry, having the composition indicated
in Table 2, was spray dried to provide aminomethylene
phosphonate-coated silicate granules. The spray-dried
coated granules comprised the sodium aminomethylene-
20 phosphonate, clay and sodium sulphate in the approximate
proportions of weight 1.3:2:1.
TABLE 2
Slurry Component Wei~ht Parts
Sodium salt of ethylenediaminetetra 81
(methylenephosphonic acid), mainly
the pentasodium salt. 33% weight
aqueous solution.
.
China clay. 70% by weight aqueous 59
slurry.
Anhydrous sodium sulphate. 20

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EXAMPLE 3
A slurry, having the composition indicated
in Table 3, was spray-dried to provide an aminomethy~
lenephosphonate-coated silicate granule. The spray-
dried coated granules comprised the sodium aminometh-
ylenephosphonate, clay and sodium sulphate in the
approximate proportions by weight 1.3:2:1.
TABLE 3
Slurry Component Weight Parts
Sodium salt of diethylenetriamine- 81
penta(methylenephosphonic acid),
mainly -the heptasodium salt.
Approx. 25% by weight aqueous
solution.
China clay. 70% by weight 59
ac~ueous slurry.
Anhydrous sodium sulphate. 20
EXAMPLE 4
This example illustrates the preparation of
detergent compositions according to this invention.
In four separate preparations, 12.5 g, 25 g,
50 g and 75 g, respectively, of Bentonite A.S. were
added to 100 g of a 33% by weight ac~eous solution of
the sodium salt of ethylenediamine tetra(methylene-
phosphonic acid), mainly the pentasodium salt. Eachslurry was diluted with distilled wa-ter to a total
volume of 400 ml and spray-dried. The coated granules
obtained by spray-drying had weight ratios of amino-
methylenephosphonate (expressed as the ec~uivalent of
active acicl~ to silicate ~"phosphonated silicate") of
1:0.5, l:l, 1:2 and 1:3 respectively. One part by
weight of the sodium salt of ethylenediamine tetra-
(methylenephosphonic acid) is ec~uivalent to approxi-
mately 0.65 parts by weight of active ethylenediamine
tetra(methylenephosphonic acid).

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A detergent formulation was prepared having
the following composition:
Ingredient % by Weiqht
Sodium tripolyphosphate 20
Sodium perborate tetrahydrate 20
Tetraacetylethylenediamine 2
IEC Standard Test Deteryent 58
IEC Standard Test Detergent as used in this
: example, has a prescribed fo:rmulation as indicated in
Table 4.
TABLE 4
IEC Standard Test Detergent (1976 Formulation)
Component % by_Wei~ht
Sodium Alkylbenzenesulfonate (N=ll.S) 17.5
; 15 Tallow Alcohol Etoxylate (14 EO)6.2
Sodium Soap 7.5
Sodium Silicate (SiO2 : NAO ~ 3.3) 16.1
Magnesium Silicate 4.1
CMC 2.6
EDTA 0.~3
Optical Brightener 0.3
Sodium Sulfate 45.6
100
: To separate samples of the above detergent
formulation, there was added sufficient quantity of
one of the spray-dried granules described above to
provide 1% by weight, based on the total weight of the
detergent formulation, of sodium ethylenediamine
tetra(methylenephosphonate) expressed as the equivalent
of active acid.
To investigate the stability of the formula
tions thus prepared, samples were placed in 100 ml
open jars and stored for 60 hours at 40C and 80%
relative humidity. The samples were then analyzed for
residual ethylenediaminetetra(methylenephosphonate)
using an ion chromatography technique. As control, a
formulation containing spray-dried sodium ethylene-
diaminetetra(methylenephosphonate) without clay, was

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employed. The beneficial effect of the clay in
stabilizing the phosphonate is apparent from the
results of the analysis shown in Table 5. Residual
phosphonate is expressed as a percentage of the
5 phosphonate originally present before storage.
T_E
Coated GranuleResidual Phosphonate
(phosphonate/silicat~pexcent)_
1:0.5 35
1:1 45
1:2 80
1:3 80
Control 7
*Aminomethylenephosphonate expressed as the equivalent
of active acid.
EXAMPLE 5
Stability tests were carried out on detergent
formulations prepared as described in Example 4 with
spray-dried coated granules containing sodium ethylene-
diaminetetra(methylenephosphonate) and various silicates(indicated in Table 6) in a weight ratio (the phosphonate
being expressed as the equivalent of active acid) of
1:2. The samples were stored overnight at 50C and
80% relative humidity and then analyzed for residual
phosphonates. The beneficial effect of the silicate
in stabilizing the phosphonate is apparent from the
results of the analysis shown in Table 6.
TABLE 6
Residual Phosphonate
Silicate ~rcent)
None o
Westone (Smectite) 60
Bentonite A.S. ~Smectite) 75
Kaolinite 1 80
Kaolinite 2 70
While the invention has been described herein
with regard to certain specific embodiments it is not

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so limited. It is to be understood that variations
and modifications thereof may be made by those skilled
in the art without departing from the spirit and scope
of the invention.