Note: Descriptions are shown in the official language in which they were submitted.
~ ~f56f~ii87
F IE LD OF I NVE N TI ON
This invention relates to an improved process for the
manufacture of dishwashing detergents in agglomerate form.
.
- BACKGROUND OF THE INVENTION
The preferred form of today's dishwashing detergents
is the agglomerate because of its slower rate of solution than
powders in the dishwasher, thereby prolonging the cleaning
action of the detergent throughout the timed dishwashing cycle. ~?
.
Such dishwashing detergents include amoung their aotive ~onstit-
` 10 uents, a source of chlorine for enhanced cleaning action, and an
?: alkaline condensed phosphate and alkaline detergent salt for ~`
.i .
~ dispersion and peptization of the dirt and soil on the dishes. ~ ~
.,. , - . ~ . .
' Where alkaline detergent salt is comprised of liquid silicates,
'~.! the liquid silicates act as the binder for the source o~ chlorine,
?,~ I5 alkaline condensed phosphate and other dry ingredients in the
.j j . .
,.`f agglomerate.
A typical dishwashing agglomerate includes sodium tri-
~;'f polyphosphate as the alkaline condensed phosphate, sodium
silicate added in solution as the alkaline detergent salt and
20 binder, and chlorinated trisodium phosphate as the source of
chlorine in amounts of between 40%-50%, 30~-35~6, and 20%-30
~ respectively. A typical agglomerate is set out below.
'~ f CONSTITUENT ~ BY WEICHT
~, . .. .
~ Sodium Tripolphosphate 42.4
; 3 25 Chlorinated Trisodium Phosphate 21. 2 ~"
~ Sodium Silicate [ 2.4: lSi02/Na20 ] 12.2S
; Sodium Silicate [3.25: 1Si02~Na20 ] 19.00
. :f
.1f Pluronic [ L 62D] * 2.00 ;~
Pluronic [ L 61 ~ * 1.00
30 Water 2.15
"f ` lOO . 00
", -1- ~ ; ~:'
. j. . .
*The pluronics are used as a source of non-ionic sur-
factant polyols which may be replaced with other forms of low
foam non-ionic detergents.
The chlorinated trisodium phosphate is particularly
desirable since it imparts to -the detergent a good buffer
capacity at high alkalinity levels during the wash cycle and per-
mits effectual sheeting action during the rinse cycle to prevent
water spots and streaks.
Insofar as the use of the liquid silicates is concerned,
it is desirable to have an SiO2:Na20 ratio, as great as possible,
for greater scrubbing action by the SiO2 and greater protection
by the colloidal silica of the patterns and overglazes of fine
china against erosion, while at the same time, not too great, so
as to deleteriously prolong the drying time of the formulated
agglomerate, which is caused by having too much SiO2. Therefore,
a delicate balance must be maintained to obtain maximum benefits
from the SiO2 added.
-I It is also desirable to limit the amount of Na20 in
the detergent because it is a major contributor to the causticity
of the detergent and erodes the glaze of fine china.
; Where sodium tripolyphosphate is used, it must be in
.:,
~ its hydrated forml i.e. sodium tripolyphosphate hexahydrate, in
-. the finished detergent product to be useful, so as not to
hydrate in the dishwasher during the wash cycle and thereby gum,
gel or cake in the dishwashing detergent dispenser, clogging same.
Therefore, such hydration must take place either prior to the
sodium tripolyphosphate being incorporated into the detergent
` formulation or during the detergent's formulation. If hydrated
prior to incorporation, the premanufactured sodium tripolyphos-
phate hexahydrate increases the cost of the formulation. If the
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i6~37
sodium tripolyphosphate is hydra-ted af-ter incorporation into the
formulation, as was usually the method employed in the prior art
formulations, the agglomerate "balled", forming large amorphous~
lumps containing up to about 15~ of the formulated agglomerate,
and to be useful, required crushing.
While the prior art has proposed the controlling of
the water content of the formulation within cer~ain limits to
minimize the "balling" and formulation o the large amorphous
lumps, this method has not been successful.
~ 10 It is therefore, an object of this invention to provide ~-
an improved process for the manufacture of a free flowing, more
uniformly agglomerated dishwashing detergent, utilizing sodium
. tripolyphosphate, whereby the amount of "balling" is reduced to
less than about 2%. .
Further and other objects, advantages and features of ~:
... .
the invention will be realized by those skilled in the art from
the ollowing summary of the invention and detailed description
: thereof.
., : ,.
SUMMAR~ OF rmE INVENTION
According to one aspect of the invention, an improved
process or the agglomerating of a dishwashing detergent
containing sodium tripolyphosphate hexahydrate is provided, in~
~ ! cluding the step of~
.~ (a) uniformly distributing an aqueous solution of ~ ~-
..~
`; 25 alkaline detergent salt onto a mixture of
.. l .
:1 constituents including sodium tripolyphosphate,
being mixed in a mixing vessel of predetermined
volume, to uniformly coat the constituents and
essentially hydrate the sodium tripolyphosphate,
j 30 the ratio of the volume of the dry constituents
:: -3-
37
.
charged into the mixing vessel prior to the
distribution of the aqueous solution of al~aline
detergent salt thereon, to the volume of air in
; the vessel, being between 1:2~ and about 1O8;
-and-
(b) mixing the formed agglomerate in the vessel to
ventilate it to the air of the vessel.
According to another aspect of the invention, an
improved process for the agglomeration of a dishwashing detergent,
including sodium tripolyphosphate hexahydrate is provided, in~
cluding the steps of: ~:
(a) charging dry constituents including sodium tripoly- ~ ;
' phosphate, which are to form part of the finished
ayglomerate into a mixing vessel of predetermined :. .
volume for the dry mixing of same~ the ratio of
. the volume of the dry constituents charged into the :
.~ mixing vessel, to the air in the vessel, being :
:~ between about 1:25 and about 1:8; ~.
.
(b) distributing an aqueous solution of alkaline
detergent salt, having an SiO2/Na20 ratio of : :
between 2.4:1 and about 3.25:1, uniformly on the
mixture so as to evenly coat the constituents and
~ essentially hydrate the sodium tripolyphosphate,
- : subsequently addin~ sufficient water if necessary
to complete the hydration; .` ~
~ (c) ventilating the agglomerate produc~; and : ; .
J (d~ subsequently sizing and aging the finished product.
-~ According to another aspect of the invention, a small
amount of water may be distributed uniformly onto the mixing
; 30 dry ingredients, prior to the addition of the aqueous solution of
: 4
:,
5~ 37
alkaline detergent salt to commence the hydration of the sodium
tripolyphosphate.
According to another aspect of the invention, the ~ ;
i vessel of predetermined volume may comprise a horizontally dis-
posed mixing drum, ro~ated about its horizontal axis, during the
agglomerating process.
According to another aspect of the invention, the
formed agglomerate may be aged for at least about 12 hours.
Preferably, the alkaline detergent salt is a sodium
silicate.
Preferably the volume of the dry ingredient to air
ratio is between about 1:18 and about 1:8. ~;
It is preferable that, where a rotating mixing drum
is used, it be disposed horiæontally and the water and alkaline
detergent salt be uniformly sprayed onto the mixture through a
, plurali-ty of nozzles, directed generally downwardly and disposed ;~
in spaced relation on an inlet, disposed on the horizontal axis ; --
of the drum. ~
... .
~l Insofar as the volume ratio between the dry constituents
and air in the vessel is concerned, the larger the ratio, the greater
, the amount of aeration that takes place, thus removing the need for
~ further drying techniques. However, if the ratio is much more
3 -
than about 1:25, a satisfactory product is not produced. Above
this ratio, there is a physical limitation on the size of the ;
mixer available today for use in the formulation of large batches.
~ With smaller batches employing a known mixing vessel, with a
:' :.
ratlo of much more than about 1:25, the ability to spray the
liquid components is greatly impaired. Insufficient powder
surface is presented to the spray of the liquid for uniform coat-
ing with the result that essentially, the wall of the clrum is
....
- -5-
,,..... .: ~;.. ... . : -
coated. ~ 7
If the ratio is much less than about 1:8, a greater
number of large moist amorphous lumps -tend to be produced and the
formulation does not benefit from sufficient aeration to preclu~de
the necessity for additional drying techniques.
Theoretically to completely hydrate the sodium tri-
polyphosphate used in the typical formulations, an amount of
water e~ual to between about 9.2~ and about 11.5% of the
formulation must be added. This water generally comes from the
aqueous solution of alkaline detergent salts.
While this invention reduces "balling" substantially,
still some lumps do result. However, they are both minimal in
size and number and may be crushed according to known procedures.
..
DETAILED DESCRIPTION OF A PREFERRED PRO OESS OF THE INVENTION
.. . .
In the description of such preferred process,
reference will be made to the schematic drawings, which illustrate
the various steps of such process in diagrammatic form.
Since the percentage composition of the components of
~ the agglomerates form no part of this invention, they will not
'";`! be referred to in the description of the steps of such process.
Exemplary percentages or amounts of the constituents in tested
formulations manufactured according to such process are listed
;` in the examples following.
; In carrying out such preferred process, a modified
Struthers-Wells mixer was used consisting of a hoxizontally
1; disposed rotatable stainless steel drum, a motor to rotate
;:J the drum about its longitudinally disposed horizontal axis,
flight bars located on the inner wall of the drum for mixing
in~redients charged into the drum, a station~ary
longitudinally extending liquid inlet situtate on the axis of
, ~ .
.
. .
37
rotation of the drum, a plurality of spray nozzles secured to the
: inlet in spaced rela-tion and directed downwardly for the uniform
; spraying of a liquid onto the components previously charged into
the drum for the uniform coating thereof.
For grinding and granulating the agglomerate formed
according to such preferred process, a Sto~es granulator was
employed having a fixed steel mesh screen and a plurality of
steel mesh screen engaging fingers for alternately recipxocally
rotating clockwise and counterclockwise through an arc of a
. 10 circle to force feed the agglomerate through the steel mesh
screen.
., .
PREFERRED PROCESS
.:, . .
. I With reerence to the schematic drawings, anhydrous
sodium tripolyphosphate [Na5P3010] and the source of chlorine,
chlorinated trisodium phosphate [4 (Na3P04.11 H20) NaOCl ] in
produced Eorm, were charged inbo the rotating Struthers-Wells
.~ . mixer l, shown in Schematic a through pivotable hopper 2 and .
.~ rotated to thoroughly mix these constituents. ~ ~
... .
II As the mixer continued to rotate:
(a) a small amount of water was sprayed onto the dry
.~ material mixture through the nozzles of the inlet
.,
~: to commence the hydration of the sodium tripoly-
phosphate, seen in Schematic b;
. ~ .
.~?l (b) an a~ueous solution of alkaline detergent salt was
::i uniformly sprayed onto the rotating material for
:?
.-:j the uniform coating thereof, seen in Schematic c;
(c) non-ionic surfactant polyols or other low foam non-
:..,
ionic detergents in solution were added -to the
~ rotating ingredients, seen in Schematic d;
:' 30 . (d) an aqueous solution of alkaline detergent salt was .
-7-
., .
668'7 ~ ~
again uniformly sprayed onto the rotating material
for the uniform coating thereof, seem in Schematic
e;
-and-
(e) a small amount of water was sprayed onto the mix-
; ing ingredients to complete the hydration of the ,
sodium tripolyphosphate and c:lean the inlet and
spray nozzles of the highly v:iscous alkaline
detergent salt solution, seen in Schematic f.
III The drum was rotated for a predetermined time after the
last addition for the ventilation of the agglomerate, seen in
.. . . .
Schematic g.
IV The formed agglomerate was then discharged from the
`' mixer by means of hopper 2 pivoted into position for discharge into
the Stokes granulator for force feeding by the fingers through the
steel mesh screen, seen in Schematic h.
V The agglomerate was then sized according to size, seen
in Schematic i.
(a) the oversized material, larger than 10 mesh was
returned to the mixer for reprocessing as a per
! cent of the initial sodium tripolyphosphate to be
`1 added;
(b) ti) the agglomerate of the desired size (
between 10 mesh and 60 mesh)~was withdrawn;
; 25 (iij subsequently aged for at least 12 hours in
fiber drums at room temperature and pressure,
See Schematic j ;
(iii) and packaged by methods known in the art;
` (c) the undersized, smaller than 60 mesh, was return-
ed to the mixing drum for reprocessing as a per-
~ centage of the sodium tripolyphosphate to be added.
; -8- -~
:.
~ ~35~137 : ~
The following ingredients comprising the indicated
agglomerated dishwashing detergent were charged into the mixing drum
at the indica~ed ~e accordinq to the ~referred ~rocess described above.
EXAMPLE A
.
6,000 pounds of agglomerated dishwasher detergent were manufactur- -
` ed according to the above process. ,~
.
STEPS ING~EiDIENTSAMQUNT STEPS ~--
Correspond to (~bs.) PERFORhMD ~ -
steps outlined ELAPSED ~-
in Preferred TIME
Process (Nearest
Minute)
I Anhydrous Sodium Tri~
polyphosphate 2544 0
.~ .
Chlorinated Trisodium
$ Phosphate 1272 15
.. . .
Ratio Of Volume Of Dry
i Constituents /Volume
Of Air in Mixing Ves~el
1:18
Mixed 24
II (a) Water 43 27
(b) Sodium Silicate
SiO2/Na20 2.4:1 735 28
`, 20 Sodium Silicate '
SiO2/Na20 3.25:1 600 52
~ (c) Pluronics - L62D 120 ) 68
-~ ~Together~ - L61 60 )
c (d) Sodium Silicate
i SiO2/Na20 3.25:1 - 540 78
., .
(e) Water 86 93
$ 25 III Ventilation of Agglomer~
ate 95
IV Discharged 155
, V Aged : About 24 Hours.
. :
EXAMPLE B
12,000 pounds of agglomerated dishwasher detergent were manufactur-
ed according to the above process.
.. _ 9 _
. . ,
r ~, .
~ ~5~l37
STEPS INGREDIENTS AMOUNT STEPS
Correspond To (lbs.) PERFORMED:
Steps Outlined ELAPSED
in Preferred
(Neare~st
Process
Mlnute )
.
I Anhydrous Sodium Tri-5088 0
- 5 polyphosphate
Chlorinated Trisodium
Phosphate 2544 30
Ratio of Volume of Dry
Constituents:Volume of
Air in Mixing Vessel-
1:18
Mixed 48
; 10 II (a) Water 74 53
- (b) Sodium Silicate ~ ;
Si02/Na20 2.4:1 1470 55
' Sodium Silicate
'! Si02/Na20 3.25:1 1200 103
(c) Pluronics L62D 240 136
L61120
(d) Sodium Silicate
2/Na2 3.25:1 1080 156
(e) Water 184 185
III Ventilation of Agglomerate 190
IV Discharged 310
20 V Aged : About 24 Hours.
` Samples were taken of the agglomerated dishwashing
detergents of Examples A and B, after Step III was carried out,
and tested with the following results.
,
FORMULATION
EXAMPLE A EXAMPLE B
~ Available Chlorine 0.69 ~ 0.61
,,,....................................................................... : .
~i Total Actives 2.80 % 2.81 %
.~
Moisture Content 26.4 % 22.8 %
Bulk Density 0.92 gm/cc 0.87 gm/cc
pH of 1% Solution 10.8 10.85 ~ ~
' ' -10- ~ :.
.: ~
. 1 .
56&j~37
Screen Analysis
on 10 mesh screens 1.4 % 0.3 ~ ',
through 60 mesh
Screens 11.9 % 10.3 ~ ,
,,, 5 Samples of other aggomerated dishwashing detergen~.s
~ manufactured according to such process were taken after Step V
', (b) (i) and samples were tested at intervals for moisture and
~ chlorine content. These samples were then aged 24 hours and again ' ~'
~ ~ .
tested for chlorine content.
10 SAMPIE
ELAPSED TIMEMOISTURE CONTENT (%) CHLORINF(~) CHLORINE
-^ ~Minutes)After 24
Hours (%)
~.~
'~, 0 27.18 .83 .81 '
`'I ,:
,10 22.45 .68 .69
~ .
`~ 15 20 ' 24.3 .71 .75
25.9 .79 .77
. ~ ~
,~ 40 26.6 ' .71 ' .72 '~
~ 50 24.6 .71 .71 ~;~
.,j , . .
'i' 60 25.2 .68 ' .66
,~ 20 Because the manufacturing process is an aggIomeration
process, the results are not uniform, due to the non-uniform
., distribution of the ingredients in the agglomerate. However, the
,~
above results show that the chlorinated ~,risodium ~hos-
~ phate does not degradate. Furthermore, there was caking in the
"''' samples tested prior to aging. However, after the agglomerate
~ was aged, no caking of the cons:tituents was observed.
'~ Samples of the aged agglomerate were packaged and
-~ stored for twenty-four hours (Step V(b) (iii)), four boxes were
'~;, opened and the dishwashing detergent was tested for moisture and
chlorine content. The agglomerate from these boxes had not
.::j
,
~ ' ~
:~ll ' ''
lCi S~137
caked and 10wed freely when poured.
: PACXAGED MATERIAL FROM SAMPLE ~:
:
BOX MOISTURE ( %)CHLORINE ( ~ )
1 26.3 .71 :~
2 26.0 .71
3 26.1 . 73 `
4 24.4 .67 '
The extent of hydration of the sodium tripolyphosphate
in the samples, based upon the amount of hexahydrate present, was
determined for each box by X-ray diffraction measurements. The
samples were compared to a sample containing 30~ sodium tripoly-
phosphate, 50% sodium tripolyphosphate hexahydrate and 20%
chlorinated tripolyphosphate. The results are set out below.
BOX % HEXAHYDRATE OF FINAL AGGLOMERATE
1 48.5 :~
,,
~ 2 56.0 ~-~
,2 3 56.0
:, ,
?~ 4 53.0 . .
As a result of the above tests, it was determined that
'. 20 substantial hydration of the anhydrous sodium tripolyphosphate
used in the samples had taken place.
-1 As a final test, packages of detergent manufactured
; according to such preferred process were given to various house- ~;
-i holds for use in their dishwashers and the comments of the members `
f the households were requested. All commented favourably on
the product.
As many changes could be made in carrying out the
j invention without departing from the scope thereof, it is intended
:~2 that all matter contained within the description of such
, .
preferred process and the general comments related thereto shall
-12-
5~6~37
be interpreted as illustrative of the invention and should not be
', interpreted in a limiting sense.
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