Suds suppressing granules for use in detergent compositions

Silicone-containing microgranules are formed by a coating process using a substantially spherical or cylindrical core material such as a sucrose bead, or an enzyme-containing prill or marume. In a preferred process the core is impregnated with an absorbent such as titanium dioxide, the absorbent is impregnated with a mixture of silicone oil and hydrophobic silica and the coated granule is then coated with wax. The granules are used in detergent compositions.

This invention relates to suds-suppressing granules and to compositions 
containing them. 
Nowadays, every major manufacturer of detergents includes in his range of 
products a fabric washing powder formulated for use in front-loading 
(drum-type) washing machines. Such machines require that the powder should 
have low sudsing characteristics. There are several ways of producing 
powders of this type, the most popular being to use soap as a 
suds-suppressing agent. Soap has some disadvantages however in respect of 
dispensibility and solubility properties so that manufacturers are 
beginning to investigate other suds-suppressing agents, among them 
phosphoric acid esters, complex nitrogen-containing compounds and mixtures 
of silicone oils with hydrophobic particles. 
This invention is concerned with these mixtures of silicone oils with 
hydrophobic particles, hereinafter referred to as silicone oil mixtures. 
It is widely appreciated in the art of detergent formulation that silicone 
oil mixtures are effective suds-suppressing agents and also that there are 
problems in incorporating these mixtures into detergent compositions. As 
described, for instance, in British Patent Specification No. 1,407,997, 
problems of reduced suds-suppressing activity on storage in detergent 
powders are encountered unless the silicone oil mixtures are protected in 
some way from interaction with the remaining components of the 
formulation. As a consequence it has been proposed to form micro-capsules 
containing silicone oil mixtures in a protective envelope designed to 
improve performance after storage. It has also been proposed that solid 
core particles can be impregnated or coated with silicone oil mixtures and 
that the resulting granules themselves can be coated with a protective 
envelope as described above. This approach is described in U.S. Pat. No. 
4,013,573. 
Despite all these developments, silicone oil mixtures have still not been 
widely used in commercial detergent products. Part of the difficulty is 
that when irregularly-shaped substances such as granular sodium 
tripolyphosphate are used as solid core material for impregnation with 
silicone oil mixtures, the resultant granule is quickly deactivated on 
storage. 
We have now discovered how to avoid the production of suds-suppressing 
granules which are quickly deactivated. 
According to the broadest aspect of the present invention there are 
provided suds-suppressing granules for use in detergent formulations 
comprising a substantially spherical or cylindrical core material and one 
or more coatings comprising a mixture of silicone oil and hydrophobic 
particles. 
The essential feature of this invention is the use of substantially 
spherical or cylindrical core material to form the granules. This results 
in the formation of regular and even layers being built-up when the core 
material is granulated for instance in an Eirich (registered trade mark) 
pan granulator or in a Schugi Flexomix (registered trade mark) mixer. This 
is particularly important when it is intended that the granule should have 
a final protective envelope, for instance, of paraffin wax, for protecting 
the silicone oil mixture coating from deactivating agents. The uniformity 
and integrity of this final envelope coating is an important factor in its 
effectiveness and we have found that the use of a substantially spherical 
or cylindrical core improves the qualities of the final coat. 
Substantially spherical or cylindrical core materials which we have found 
satisfactory are beads comprising sucrose, developed particularly for the 
pharmaceutical industry for the manufacture of pills, spherical 
enzyme-containing prills and substantially cylindrical enzyme-containing 
marumes and Alcalase T granules (registered trade mark) manufactured and 
sold by Novo Industries. The sucrose beads have an average diameter of 
from 0.1 to 3 mm and are made from a mixture comprising molten sucrose by 
a spray cooling process. Enzyme-containing prills and marumes are produced 
by a granulation process and are commercially available from manufacturers 
of enzymes suitable for detergents use, such as Novo Industries AB. 
While granules simply comprising the core material coated with silicone oil 
mixtures are within the scope of the invention, it is preferred that a 
more complex granule is produced. The preferred granule has a core coated 
with particulate absorbent. The absorbent is impregnated with the silicone 
oil mixture and the resultant particle is coated with a protective 
envelope. Although starch and titanium dioxide are the materials preferred 
for use as absorbents other materials can be used. Examples of these are 
sodium carboxymethyl cellulose, cellulose ethers, finely-divided silica 
and calcite. Paraffin wax is preferred for use as a protective envelope, 
particularly a paraffin wax having a melting point in the range 35.degree. 
to 65.degree. C. Other protectants which can be used are fatty alcohols, 
ethoxylated fatty alcohols, fatty acids, fatty acid esters and phosphoric 
acid esters. 
In general the various components may be present in the preferred granules 
in the following amounts: 
______________________________________ 
core material 25-80% 
absorbent 15-40% 
silicone oil mixture 
5-30% 
protective envelope material 
3-30% 
______________________________________ 
the percentages being expressed by weight of the total granule.

The following Examples illustrate the use of the invention is detergent 
compositions and the properties of the granules in comparison with known 
suds-suppressing materials. 
EXAMPLE 1 
Two detergent powders having the formulations shown below were prepared by 
spray-drying and dry-dosing techniques. 
______________________________________ 
% by weight 
A B 
______________________________________ 
Sodium alkylbenzene sulphonate 
9.0 15.0 
Nonionic surfactant 3.0 3.0 
Sodium tripolyphosphate 
34.0 40.0 
Sodium silicate 6.0 6.0 
Sodium perborate 24.0 -- 
Silicone-containing granules 
1.6 1.7 
Sodium sulphate 
Minor components to 100 to 100 
Moisture 
______________________________________ 
In the case of Composition A the silicone-containing granules which were in 
accordance with the prior art have the composition: 
______________________________________ 
% by weight 
______________________________________ 
Sodium tripolyphosphate 
75 
Silicone mixture 10 
Paraffin wax 15 
______________________________________ 
and in the case of Composition B: 
______________________________________ 
% by weight 
______________________________________ 
Sucrose beads 60.2 
Silicone mixture 
12 
Starch 24 
Paraffin wax 4.8 
______________________________________ 
These granules were made by the general method described below. 
Substantially spherical core material in the form of beads of sucrose are 
granulated in an inclined pan granulator with an absorbent, for example 
starch, titanium dioxide or a cellulose ether, and a solution/dispersion 
of a silicone oil mixture in an organic solvent is sprayed onto the 
particles thereby obtained. The solvent is then evaporated. A protective 
envelope is then formed over the silicone-impregnated absorbent by 
spraying a second solution, for example a solution of a paraffin wax in a 
solvent, preferably one which does not dissolve silicone oil onto the 
particles. The second solvent is also evaporated. 
The suds-suppressing properties of detergent compositions containing the 
granules of the invention were assessed in a Brandt 432 (registered trade 
mark) Washing Machine using the 60.degree. and 95.degree. C. cycles. The 
load was 4 kg of cotton cloth or 2 kg of synthetic cloth and 200 grams of 
powder was used in each wash cycle. 
The height of suds appearing at the port-hole of the washing machine was 
measured against an arbitrary scale at a series of time intervals during 
the heat-up period and the temperature of the wash liquor was measured 
simultaneously. 
Normally, three assessments were carried out, the first on powder which was 
freshly prepared and the second and third on powder which had been stored 
for one month at 37.degree. C./70% relative humidity and at 22.degree. 
C./90% relative humidity respectively. 
The results for Compositions A and B, using slightly dirty wash goods, are 
shown in FIG. 1 and demonstrate that although Powder A containing silicone 
granules formed from an irregularly shaped substrate such as sodium 
tripolyphosphate produces an acceptable quantity of suds when freshly 
prepared, the suds-suppressing activity of the granules falls off on 
storage to such an extent that, when used in a washing machine, 
over-foaming would be produced. In contrast, Powder B, containing granules 
formed on substantially spherical beads of sucrose is low sudsing both 
when freshly prepared and after storage, even though the basic 
formulation, because of its higher content of alkylbenzene sulphonate, is 
essentially high foaming. 
EXAMPLE 2 
Two detergent powders having the formulations shown below were prepared by 
spray-drying and dry-dosing techniques. 
______________________________________ 
% by weight 
C D 
______________________________________ 
Sodium alkylbenzene sulphonate 
7.0 7.0 
Sodium stearate 4.0 -- 
Sodium behenate -- 1.0 
Nonionic surfactant 3.5 3.5 
Sodium tripolyphosphate 
34.0 34.0 
Sodium silicate 6.0 6.0 
Sodium perborate 24.0 24.0 
Silicone-containing granules 
-- 0.3 
Sodium sulphate 
to 100 to 100 
Moisture and minor components 
______________________________________ 
The composition of the silicone-containing granules, which were 
manufactured by the method described in Example 1, was as follows: 
______________________________________ 
% by weight 
______________________________________ 
Sucrose beads 55.6 
Titanium dioxide 22.8 
Silicone mixture 10.6 
Paraffin wax 10.6 
Silanated titanium dioxide 
0.4 
______________________________________ 
The quantity of foam produced by the powders during a washing procedure was 
assessed as described in Example 1. Although powders which had been stored 
at 37.degree. L C./70% Relative Humidity and 22.degree. C./90% Relative 
Humidity were tested in the case of Powder D, there was no substantial 
difference between the results obtained for freshly prepared or for stored 
powder. The results obtained using slightly dirty wash goods are shown in 
FIG. 2. 
It can be seen from FIG. 2 that in the important high temperature region 
between 50.degree. and 90.degree. C., Powder D containing 1% of soap and 
0.3% of the silicone-containing granules of the invention formed on 
sucrose beads produces less foam than Powder C formulated with 4% of 
sodium stearate. 
EXAMPLE 3 
Two detergent powders having the formulations shown below were prepared as 
before. 
______________________________________ 
% by weight 
E F 
______________________________________ 
Sodium alkylbenzene sulphate 
7.0 9.0 
Sodium stearate 4.0 -- 
Nonionic surfactant 3.5 3.0 
Sodium tripolyphosphate 34.0 34.0 
Sodium perborate 24.0 24.0 
Sodium silicate 6.0 6.0 
Silicone granules -- 1.4 
______________________________________ 
The composition of the silicone granules was as follows: 
______________________________________ 
% by weight 
______________________________________ 
Silicone mixture 10.6 
Titanium dioxide 22.8 
Microcrystalline wax 60/63 
10.6 
Enzyme marumes 55.6 
______________________________________ 
The quantity of suds produced by the powders during a washing procedure was 
assessed as described in Example 1, both for freshly prepared powder and, 
in the case of Powder F, for powder which had been stored for one month at 
ambient temperature and humidity, at 22.degree. C. and 90% relative 
humidity and at 37.degree. C. and 70% relative humidity. The results 
obtained using clean wash goods are shown in FIG. 3. 
From the Figure, it can be seen that the silicone-containing granules 
formed on enzyme marumes were substantially more efficient at suppressing 
suds at a level of 1.4% than was 4% of sodium stearate, despite the fact 
that Powder F contained higher ratio of anionic to nonionic surfactant and 
therefore had a higher inherent foaming tendency. 
It can also be seen that the deactivation of the granules during storage 
was relatively minor. 
In all the above Examples, the silicone mixture used for preparation of the 
granules was Silicone DB100 (trade mark) manufactured by Dow Corning, 
which is a mixture of a polysiloxane and a hydrophobic silica. 
The efficiency of the powder containing the granules of the invention in 
suppressing suds is apparent, particularly at the higher temperature. 
It will be understood that this invention is concerned with the 
suds-suppressing component of a detergent powder and consequently no 
attempt has been made in this specification to describe all possible 
powders to which the component could be added. It is self-evident that the 
usual detergent composition components are appropriate provided that they 
have no adverse reaction with silicone oil mixtures. For example, anionic 
surfactants such as alkylbenzene sulphonates, primary and secondary alkyl 
sulphates, secondary alkane sulphonates, soaps and olefine sulphonates can 
be used. Nonionic surfactants, either alone or in combination with anionic 
surfactants can also be used, the preferred nonionic surfactants being 
C.sub.7 to C.sub.24 primary or secondary alcohols ethoxylated with from 1 
to 25 moles of ethylene oxide per mole of alcohol. Typical amounts of 
surfactant are from 3 to 25% by weight when only one species is present, 
and from 1 to 12% by weight when more than one is present. 
Builders may be present in amounts of from 5 to 50% by weight. Typical of 
the inorganic builders are sodium tripolyphosphate, sodium pyrophosphate 
and sodium orthophosphate, sodium carbonate and the crystalline and 
amorphous forms of aluminosilicates. Organic builders such as sodium 
nitrilotriacetate, sodium citrate, sodium carboxymethyloxysuccinate, and 
the host of other materials which have been suggested as phosphate 
replacers are also appropriate. 
Other components which may be present are sodium silicate as a corrosion 
inhibitor and powder structural oxygen bleaches such as sodium perborate 
and sodium percarbonate, fluorescers, antiredeposition agents and 
anti-ashing agents, suds-suppressing agents other than the silicone 
granules of the invention, and moisture. PG,12