Freeflowing alkaline detergent, and agents for the preparation thereof

A particulate alkaline detergent contains an alkaline agent and an alkali perborate hydrate and/or an alkali carbonate peroxohydrate as bleaching agent. As a result of coating at least the alkaline agent or the bleaching agent with an alkyl glycoside or an alkyl glycamide, the detergent has a low tendency to caking as well as excellent cleaning capacity. The alkyl glycoside is a C.sub.6 -C.sub.10 -alkyl glycoside having a degree of polymerization of 1-4, and the alkyl glycamide has formula (I), wherein R.sub.1 is hydrogen or an alkyl group having 1-4 carbon atoms, and R.sub.2 is an alkyl group having 6-10 carbon atoms. A bleaching agent and an alkaline agent coated with the alkyl glycoside and/or the alkyl glycamide are also disclosed.

The present invention relates to a particulate alkaline detergent 
containing an alkaline agent and an alkali perborate hydrate and/or an 
alkali carbonate peroxohydrate as bleaching agent. As a result of coating 
at least the alkaline agent or the bleaching agent with an alkyl glycoside 
or an alkyl glycamide, the detergent has a low tendency to caking and 
excellent cleaning capacity. 
When stored, particulate detergents, such as machine dishwashing 
detergents, easily cake, probably because weakly bound water migrates from 
one component to another, thereby forming so-called salt bridges. It is 
known that small amounts of chlorine isocyanurates, which are used as 
bleaching agents, can prevent caking. Patent Specification DE 3,818,660 
A1, for instance, discloses such machine dishwashing detergents. It has, 
however, been found that chlorine isocyanurates in alkaline aqueous 
solutions generate organic chlorine compounds, such as tetrachlorine 
dibenzo paradioxine, which are toxic as well as not readily biodegradable. 
Thus, there is every reason to avoid using chlorine isocyanurates as 
bleaching agents and anti-caking agents. 
Chlorine-free and comparatively environment-friendly bleaching agents 
include alkali perborate hydrates, such as sodium perborate monohydrate 
and sodium perborate tetrahydrate, and alkali carbonate peroxohydrates, 
such as sodium carbonate peroxo-1,5-hydrate. Such agents do, however, 
exhibit a marked tendency towards caking, which usually is intensified if 
the bleaching agents are used together with silicate as the alkaline 
agent. Attempts to use surface-active agents as anti-caking agents have 
only met with limited success, since it has not been possible to combine 
satisfactory anti-caking capacity with satisfactory cleaning capacity with 
regard to fat, starch, protein and tea. 
One object of this invention is to replace chlorine isocyanurates with more 
environment-friendly bleaching agents in freeflowing alkaline detergents, 
such as particulate alkaline dishwashing detergents. Another object of the 
invention is to select the components of the detergent in such manner that 
it does not contain any special anti-caking agents and is given excellent 
cleaning capacity. 
It has been found that these objects are achieved by using alkyl glycosides 
or glycamides as a combined surface-active agent and anti-caking agent. 
More specifically, the invention relates to a particulate alkaline 
detergent containing a conventional complexing agent, characterised in 
that it further contains 
a) 0.05-10% by weight, preferably 0.05-4% by weight, and most preferably 
0.2-2.5% by weight of a C.sub.6 -C.sub.10 -alkyl glycoside having a degree 
of polymerisation of 1-4, a glycamide of formula 
##STR1## 
wherein R.sub.1 is hydrogen or an alkyl group having 1-4 carbon atoms, 
and R.sub.2 is an alkyl group having 6-10 carbon atoms, or a mixture 
thereof, 
b) 10-80% by weight, preferably 20-70% by weight of a water-soluble 
inorganic alkaline agent, and 
c) 1-80% by weight, preferably 1-20% by weight, and most preferably 3-15% 
by weight of an alkali perborate hydrate and/or an alkali carbonate 
peroxohydrate, at least one of components b) and c), and, optionally, 
other components of the detergent, being coated with component a). In a 
preferred embodiment, both the alkaline agent b) and the bleaching 
chemicals c) are surface-coated with component a), suitably together with 
other components, such as the complexing agent. A suitable coating is 
obtained by dissolving the alkyl glycoside or the glycamide in a solvent, 
e.g. water and/or ethanol, and is sprayed onto a powder of the components 
to be coated, whereupon the thus-sprayed powder is dried in a manner known 
per se. Also other conventional processes of coating may be employed. 
If only one of components b) and c) is coated with alkyl glycoside or 
glycamide, the content thereof may become so low that another 
surface-active agent should be added to the detergent to give the desired 
cleaning capacity. Apart from adding more alkyl glycoside or glycamide, 
other surface-active agents can be added, such as amphoteric compounds, 
non-ionic compounds or mixtures thereof, or a mixture of non-ionic and 
anionic compounds. If the detergent is a dishwashing detergent, 
low-foaming surface-active agents or mixtures of such agents should be 
used. Supplementary surface-active agents may also be added to adapt, and 
thereby optimise, the detergent to different applications. 
U.S. Pat. No. 4,675,127 discloses the use of alkyl glycosides in 
particulate detergent compositions. In this case, the alkyl glycoside is 
to contribute to reducing the viscosity and increasing the homogeneity of 
the aqueous slurry to be spray-dried. Further, DE-A1-3,925,858 discloses 
the coating with an alkyl glycoside of a chemically and physiologically 
inert carrier which in water is neutral or weakly alkaline. However, these 
patent specifications do not provide any guidance on how to avoid caking 
in a particulate alkaline composition according to the invention. 
The specific alkyl glycosides used in the invention have an alkyl group 
with 6-10 carbon atoms and a degree of polymerisation of 1-4. 
Conveniently, the length of the alkyl chain and the degree of 
polymerisation are so chosen that the alkyl glycoside obtains a HLB value 
of 16-21. Preferably, the alkyl group has 7-9 carbon atoms and the degree 
of polymerisation is 1.0-2.0. In detergent compositions according to the 
invention, such alkyl glycosides have been found to give excellent 
cleaning capacity, suitable foaming, and a low tendency towards caking. 
Suitable alkyl groups include n-heptyl, 2-ethyl hexyl, n-octyl, isononyl, 
n-nonyl and n-decyl. 
In the glucamide, R.sub.2 conveniently is n-heptyl, 2-ethyl hexyl, 
isononyl, n-nonyl and n-decyl, and R.sub.1 conveniently is methyl or 
ethyl. 
As water-soluble alkaline agents, use is primarily made of sodium 
silicates, sodium carbonates, sodium borates and sodium hydroxide or 
mixtures thereof. Preferably, use is made of sodium silicate, optionally 
combined with sodium carbonate. In strongly alkaline dishwashing 
detergents, i.e. detergents that give a pH exceeding 11, preferably 
exceeding 11.5, in a 1% aqueous solution, use is conveniently made of an 
alkaline agent of which at least 50% by weight is a sodium meta-silicate 
with or without hygroscopic water. For weakly alkaline dishwashing 
detergents, i.e. dishwashing detergents that have a pH below 11, 
preferably 9-11, in a 1% aqueous solution, use is preferably made of an 
alkaline agent of which at least 10% by weight is a sodium silicate in 
which the molar ratio of SiO.sub.2 to Na.sub.2 O is 1.0-3.5, preferably 
2.0-2.4. Advantageously, these silicates are combined with alkaline 
buffers, e.g. sodium hydrogen carbonate. The cleaning capacity of weakly 
alkaline detergents may further be enhanced by an addition of enzymes, 
since the stability of the enzymes is not affected by the bleaching agents 
used in the invention or by the moderately alkaline pH. Suitable enzymes 
are amylases and proteases. 
Usually, the alkali perborate hydrate and the alkali carbonate 
peroxohydrate are sodium compounds, such as sodium perborate monohydrate, 
sodium perborate tetrahydrate and sodium carbonate peroxo-1,5-hydrate. If 
desired, the two bleaching agents can be mixed with one another, but 
sodium perborate monohydrate is usually preferred as bleaching agent owing 
to its excellent stability and cost effectiveness. 
Suitably, component c) is coated with at least some of component a) in a 
separate step, it being possible to apply comparatively large amounts of 
component a) on the bleaching agents making up component c). This results 
in a satisfactory anti-caking effect, since the bleaching agents making up 
component c) belong to those components of the detergent that form salt 
bridges. Thus, the present invention also concerns a particulate bleaching 
agent consisting of an alkali perborate hydrate and/or an alkali carbonate 
peroxohydrate and coated with 0.5-20% by weight, preferably 0.5-10% by 
weight, and most preferably 1-5% by weight of a C.sub.6 -C.sub.10 -alkyl 
glycoside having a degreee of polymerisation of 1-4 and/or a glycamide of 
formula (I). 
Also the particulate alkaline agent may advantageously be coated with 
component a), since this agent markedly contributes to the formation of 
salt bridges. Thus, the present invention also concerns a particulate, 
water-soluble and inorganic alkaline agent coated with 0.2-10% by weight, 
preferably 0.2-5% by weight, and most preferably 0.5-2.5% by weight of a 
C.sub.6 -C.sub.10 -alkyl glycoside having a degree of polymerisation of 
1-4 and/or a glycamide of formula (I). Preferably, at least 10% by weight 
of the alkaline agent is a sodium silicate. 
The complexing agent may be inorganic as well as organic. Suitable 
complexing agents include polymeric inorganic phosphates, such as 
tripolyphosphates and pyrophosphates; organic compounds, such as nitrilo 
triacetates, ethylene diamine tetraacetates and phosphonates; and 
multi-functional carboxylic acids, such as citrates. Other complexing 
agents are zeolites and carboxylate-group-containing polymers, such as 
polyacrylates. Polyphosphates are the most common complexing agents, but 
the use of polyphosphates is being questioned owing to their fertilising 
effect on watercourses. By using a perborate as bleaching agent, it is 
possible to considerably reduce the polyphosphate content without 
impairing the cleaning capacity of the detergent. Usually, the complexing 
agent makes up 10-40% of the particulate detergent. 
Apart from the components indicated above, the detergent according to the 
invention may contain a number of other common additives, such as 
colouring agents, defoamers, solubilising agents, perfume, 
anti-redeposition agents, such as cellulose derivatives and water-soluble 
fillers. The content of these additives may vary within wide limits, but 
usually is 0-20% by weight of the detergent. 
Strongly alkaline particulate dishwashing detergents according to the 
invention suitably have the following composition: 
______________________________________ 
Component % by weight 
______________________________________ 
Complexing agent, preferably 
10-35 
sodium tripolyphosphate 
C.sub.8 -alkyl glycoside (degree of 
0.5-2.5 
polymerisation of 1.0-2.0) 
or C.sub.8 -alkyl glycamide 
Alkaline agents of which at least 
35-80 
50% by weight is sodium meta- 
silicate 
Sodium perborate monohydrate and/or 
3-15 
sodium carbonate peroxo-1,5-hydrate 
Other components 0-15 
______________________________________ 
Weakly alkaline particulate dishwashing detergents according to the 
invention suitably have the following composition: 
______________________________________ 
Component % by weight 
______________________________________ 
Complexing agent, preferably 
20-50, preferably 
sodium tripolyphosphate, 
20-40 
polycarboxylate, sodium 
citrate 
C.sub.8 -alkyl glycoside (degree of 
0.5-8, preferably 
polymerisation of 1.0-2.0) 
0.5-2.5 
or C.sub.8 -alkyl glycamide 
Alkaline agent of which at least 
5-70, preferably 
10% by weight is a sodium sili- 
10-60 
cate having a SiO.sub.2 :Na.sub.2 O ratio 
of 2.0-2.4 
Sodium perborate monohydrate and/ 
3-40, preferably 
or sodium carbonate peroxo-1,5- 
3-15 
hydrate 
Other components 2-30, preferably 
5-20 
______________________________________

The invention will now be illustrated in more detail with the aid of the 
following Examples. 
EXAMPLES 1-5 
A particulate composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium metasilicate, 4 parts by 
weight of sodium carbonate and 10 parts of sodium perborate monohydrate 
was coated with 2 parts by weight of one of the alkyl glycosides below or 
with octyl-N-methyl glucamide. The resulting dishwashing detergent 
compositions and the basic formulation were tested as to caking after 
storing for 24 hours at 40.degree. C. and 60% RH. The degree of caking was 
assessed by visual inspection on a scale from 1 to 5, in which 
1=freeflowing, 2=freeflowing with lumps (about 25%), 3=about 50% caked, 
4=about 75% caked, and 5=completely caked. The following results were 
obtained. 
______________________________________ 
Example Surface-active agent 
Caking 
______________________________________ 
Control 1 -- 2 
1 AG-8-1.1 1 
2 AG-8.sup.1 -1.1 
1 
3 AG-8.sup.1 -1.5 
1 
4 AG-8-2.0 1 
5 Octyl-N-methyl 
1 
glucamide 
______________________________________ 
AG-8-1.1=octyl glucoside having a degree of polymerisation of 1.1. 
AG-8.sup.1 -1.1=2-ethyl hexyl glucoside having a degree of polymerisation 
of 1.1. 
AG-8.sup.1 -1.5=2-ethyl hexyl glucoside having a degree of polymerisation 
of 1.5. 
AG-8-2.0=octyl glucoside having a degree of polymerisation of 2.0. 
As appears from the results, the detergent composition of the invention is 
freeflowing, whereas the pulverulent composition without alkyl glycoside 
or alkyl glycamide exhibits tendencies towards caking. 
EXAMPLES 6 AND 7 
To a particulate composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium metasilicate and 4 parts by 
weight of sodium carbonate was added 10 parts by weight of sodium 
perborate monohydrate which had been treated with 2 parts by weight of an 
alkyl glycoside. Then, caking tests as in Examples 1-5 were performed, 
yielding the following results. 
______________________________________ 
Example Alkyl glycoside 
Caking 
______________________________________ 
Control 2.sup.a) 
-- 2 
Control 3.sup.b) 
-- 3 
Example 6 AG-8-1.1 1 
Example 7 AG-8.sup.1 -1.1 
1 
______________________________________ 
.sup.a) in the absence of sodium perborate monohydrate 
.sup.b) in the presence of untreated sodium perborate monohydrate. 
It is evident from the results that a freeflowing dishwashing detergent is 
obtained also when only the sodium perborate monohydrate is treated with 
alkyl glycoside. 
EXAMPLES 8 AND 9 
A pulverulent composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium meta-silicate and 4 parts 
by weight of sodium carbonate was coated with 2 parts by weight of an 
alkyl glycoside, whereupon 10 parts by weight of sodium perborate 
monohydrate was added. The tendencies towards caking were established as 
in Examples 1-5, giving the following results. 
______________________________________ 
Example Alkyl glycoside 
Caking 
______________________________________ 
Control 4.sup.a) 
AG-8-1.1 1 
Control 5.sup.a) 
AG-8.sup.1 -1.1 
1 
Example 8 AG-8-1.1 1 
Example 9 AG-8.sup.1 -1.1 
1 
______________________________________ 
.sup.a) without bleaching agent 
It is clear from these results that a freeflowing dishwashing detergent is 
obtainable also when the basic composition, including alkaline agents, has 
been coated with alkyl glycoside, while the bleaching agent remains 
uncoated. 
EXAMPLES 10 AND 11 
A particulate composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium metasilicate, 4 parts by 
weight of sodium carbonate and 10 parts by weight of sodium perborate 
monohydrate was coated with 2 parts by weight of alkyl glycoside, 
whereupon caking tests were performed at 20.degree. C. and 60% RH, as in 
Examples 1-5. For comparison, the particulate composition was tested also 
in the absence of alkyl glycoside, and further tested after having been 
coated with a conventional non-ionic alkylene oxide adduct, Plurafac LF 
403. The following results were obtained. 
______________________________________ 
Example Surface-active agent 
Caking 
______________________________________ 
Control 6 -- 4.5 
Control 7 Plurafac LF 403 
5.0 
Example 10 AG-8-1.1 3.0 
Example 11 AG-8.sup.1 -1.1 
1.5 
______________________________________ 
It is evident from these results that the presence of alkyl glycoside 
according to the invention considerably reduces tendencies towards caking, 
whereas the presence of a conventional non-ionic alkylene oxide adduct 
common in dishwashing detergent compositions instead intensifies 
tendencies towards caking. 
EXAMPLES 12 AND 13 
A particulate composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium metasilicate, 4 parts by 
weight of sodium carbonate and 10 parts by weight of sodium perborate 
monohydrate was coated with 2 parts by weight of an alkyl glycoside. The 
cleaning capacity of the resulting dishwashing detergent was then tested 
in a household dishwasher at 55.degree. C. with regard to starch, protein 
and fat. For comparative purposes, tests were also performed on the 
particulate composition without alkyl glycoside. The cleaning effect was 
measured by means of a spectrophotometer after the remaining soil had been 
coloured with iodine. The cleaning effect was assessed on a scale from 1 
to 10, in which 1 represents washing up with clean water, and 10 
represents a completely clean plate. The following results were obtained. 
______________________________________ 
Cleaning effect 
Example Alkyl glycoside 
Starch Protein 
Fat 
______________________________________ 
Control 8 
-- 8.5 5.5 3.5 
Example 12 
AG-8-1.1 9.5 7.3 10 
Example 13 
APG-8.sup.1 -1.1 
9.3 6.0 10 
______________________________________ 
As is apparent, the presence of alkyl glycoside considerably improved the 
cleaning capacity. 
EXAMPLES 14 AND 15 
A particulate composition consisting of 35 parts by weight of sodium 
citrate, 29 parts by weight of sodium disilicate, 10 parts by weight of 
sodium carbonate, 13 parts by weight of sodium sulphate, 1 part by weight 
of magnesium sulphate, and 10 parts by weight of sodium perborate 
monohydrate was coated with 2 parts by weight of alkyl glycoside. The 
resulting low-alkaline dishwashing detergent was tested as to caking at 
20.degree. C. and 60% RH as in Examples 1-5. The results were as follows. 
______________________________________ 
Example Alkyl glycoside 
Caking 
______________________________________ 
Control 9 -- 2 
Example 14 AG-8-1.1 1 
Example 15 AG-8.sup.1 -1.1 
1 
______________________________________ 
It is obvious that the low-alkaline dishwashing detergent according to the 
invention give freeflowing compositions, whereas the corresponding 
composition without alkyl glycoside exhibits tendencies towards caking. 
EXAMPLES 16 AND 17 
A particulate composition consisting of 27 parts by weight of sodium 
tripolyphosphate, 67 parts by weight of sodium metasilicate, 4 parts by 
weight of sodium carbonate and 10 parts by weight of sodium carbonate 
peroxo-1,5-hydrate was coated with 2 parts by weight of an alkyl glycoside 
in accordance with the Table below. The resulting dishwashing detergent 
compositions as well as, for comparative purposes, the basic formulation 
proper and the basic formulation coated with a non-ionic surface-active 
agent (Plurafac LF 403) were tested as to caking after storage for 24 
hours at 40.degree. C. and 60% RH, as in Examples 1-5. The following 
results were obtained. 
______________________________________ 
Example Surface-active agent 
Caking 
______________________________________ 
Control 10 -- 3 
Control 11 Plurafac LF 403 
3 
Example 16 AG-8-1.1 1 
Example 17 AG-8.sup.1 -1.1 
1 
______________________________________ 
It is clear that the dishwashing detergents formulated according to the 
invention have much better freeflowing properties than the compositions 
included for comparative purposes.