Note: Descriptions are shown in the official language in which they were submitted.
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WO 94/05762 PCT/EP93/02252
TRANSLATION
A dishwashing detergent containing a selected builder
system
This invention relates to a solid dishwashing
detergent for use in dishwashing machines.
In addition to surfactants, machine dishwashing
detergents of the latest phosphate-free generation
contain oxygen-based oxidizing agents and a relatively
complex builder combination of alkali metal carbonates
and organic complexing agents. The organic complexing
agents hitherto used include organophosphonic acids,
hydroxycarboxylic acids, aminocarboxylic acids and, in
particular, polymeric polycarboxylic acids, which are
often used in admixture with low molecular weight poly-
hydroxypolycarboxylic acids, for example citric acid, or
water-soluble salts thereof. In general, alkali metal
silicate is additionally present as a further builder
component. Detergents with this composition are often
attended by the disadvantage that they form lime bloom
both in the dishwashing machine and in particular on its
clean contents, particularly where the water used is
relatively hard.
It has now surprisingly been found that the bloom
formed by the dishwashing detergent in conjunction with
the hardness constituents of water can be inhibited by
using a builder combination containing certain oxidation
products of polyglucosans.
Accordingly, the present invention relates to a
solid, low-alkali, phosphate- and chlorine-free machine
dishwashing detergent containing organic water-soluble
builder, alkali metal carbonate, oxygen-based bleaching
agent, surfactant and if desired other typical constitu-
ents, characterized in that it contains oxidation prod-
ucts of polyglucosans and/or soluble salts thereof as the
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Wo 94/05762 2 PCT/EP93/022S2
builder component.
In the context of the present invention, oxidation
products of polyglucosans are understood to be polymers
of monosaccharides which consist at least partly of
oxidized anhydroglucose units with one, two or three
carboxyl groups per unit. These oxidized anhydroglucose
units correspond to the following structural formulae I,
II or III:
1 0 COOH
~ (I)
J\~O H
OH
cH2oH
_ (II)
COOH COOH
,COOH
~
(III)
COOH COOH
Extensive knowledge exists on the production of such
polysaccharide derivatives by oxidative treatment of, for
example, cellulose, starch and dextrins, cf. for example
Houben-Weyl "Methoden der organischen Chemie~, Thieme-
Verlag, Stuttgart (1987), Vol. E 20, Makromolekulare
Stoffe, sub-chapter entitled "Polysaccharide Derivatives"
edited by Dr. K. Engelskirchen, loc. cit., pages 2042 et
seq., more particularly pages 2124 et seq. (oxidation
products of cellulose) and pages 2166 et seq. (oxidized
starches); and "Cellulose Chemistry and Its Applications"
(1983), John Wiley & Sons, Chichester, GB, more particu-
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WO 94/05762 3 PCT/EP93/02252
larly T.P. Nevell, "Oxidation of Cellulose" (Chapter 10),
and the extensive literature cited therein, loc. cit.
pages 262 to 265; and European patent applications EP 425
369, EP 455 522 and EP 472 042.
Broadly summarized, it may be said that a large
number of oxidizing agents are used for the oxidation of
polyglucosans, including for example (atmospheric)
oxygen, hydrogen peroxide, sodium hypochlorite or bro-
mite, periodic acid and periodates, lead(IV) acetate,
nitrogen dioxide and cerium(IV) salts. These oxidizing
agents react very differently with the anhydroglucose
units, cf. for example the formula schemes in Houben-
Weyl, loc. cit., page 2124. It is known that, when
cellulose is exposed to the action of nitrogen dioxide,
oxidation of the primary alcohol group to the carboxy
group is by far the predominant reaction. The oxidizing
agent may be used in gaseous form or in the form of a
solution in an inert organic solvent, cf. also Houben-
Weyl, loc. cit., page 2125 and the primary literature
cited in this connection. Even where starch is used as
the starting material, largely selective oxidations of
the primary alcohol group of the anhydroglucose unit to
the carboxy group can be achieved. The teaching accord-
ing to the present invention is based on this knowledge
of the prior art.
For example, monocarboxyl starches with a freely
selectable degree of reaction of the primary alcohol
groups can be obtained by selective oxidation with nitro-
gen dioxide at low temperatures, even in the absence of
auxiliaries, for example solvents or catalysts. Substan-
tially quantitative and largely selective reaction of the
structural elements of the starch molecule is also
possible.
However, a quantitative reaction such as this is not
necessary for the purpose according to the invention of
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WO 94/05762 4 PCT/EP93/02252
using derivatives of natural substances of the type in
question as builders in the detergents mentioned. In-
stead, what is crucial is the interplay between the fol-
lowing two parameters: adequate conversion of the primary
alcohol groups into carboxy groups and, on the other
hand, regulation of the average molecular weight of the
natural polyglucosan molecule to sufficiently degraded
fragments. The first of these two parameters would
appear to be of functional significance to the inter-
action, for example with the hardness constituents, whilethe sufficiently limited average molecular weight of the
modified polyglucosan units can be important inter alia
for the sufficient solubility of the builder under in-use
conditions.
The following observations apply to these two
parameters:
The preferred lower limit to the content of oxidized
anhydroglucose units corresponding to formula I, II
and/or III in the polyglucosan derivatives is at around
25 mole-% and preferably at at least around 35 mole-% to
40 mole-%. The substantially quantitative conversion of
one, two or three alcohol groups into carboxy groups is
possible so that the upper limit to the corresponding
content of oxidized anhydroglucose units is at 95 mole-%
to around 100 mole-%. Corresponding oxidation products
characterized by contents of around 35 mole-% to 80 mole-
% of oxidized anhydroglucose units can be particularly
suitable for practical application, their content in one
important embodiment being in the range from about 40
mole-% to 60 mole-%.
It has been found, particularly in the field of
starch derivatization in accordance with the invention,
that, in the oxidative treatment of dry starch which
normally contains limited quantities of water with NO2
and, optionally, conversion of the oxidation products
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Wo 94/~5762 5 PCT/EP93/02252
into water-soluble salts, the largely selective oxidation
of the primary alcohol groups is accompanied by a reduc-
tion in the molecular weight of the starch molecule to
such an extent that the derivatized polyglucosans obtain-
ed are particularly suitable for use as builders and formaqueous solutions having viscosities in the range men-
tioned above.
On a statistical average, at least 15 mole-% of the
oxidized polyglucosans to be used in accordance with the
invention preferably consist of anhydroglucose units
corresponding to formula I, the oxidized polyglucosans
having average molecular weights below 15,000.
The builder component corresponding to the defini-
tion according to the invention is used in the dishwash-
ing detergents in quantities of preferably 5 to 60% byweight and, more preferably, 10 to 40% by weight, based
on the total weight of the detergent. In many cases,
quantities of 15% by weight to 30% by weight can be
useful. The builder component may be used both in the
form of the free carboxylic acid and in the neutralized
form, more particularly in the form of the alkali metal
salts. Where the free carboxylic acid is used, the
alkali metal salts are generally formed under in-use
conditions.
The composition of the detergents may otherwise be
selected virtually as required within the limits of known
formulations.
Machine dishwashing detergents according to the
invention contain as their principle components surfac-
tants, the builder component according to the invention,
peroxy bleaching agents and other typical ingredients of
dishwashing detergents, such as enzymes, dyes and fra-
grances, alkalizing agents, such as soluble alkali metal
silicates, and optionally neutral salts and water.
Among the compounds yielding H2O2 in water which
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serve as bleaching agents, sodium perborate tetrahydrate
(NaBO2-H2O2-3H2O) and sodium perborate monohydrate
(NaBO2-H2O2) are particularly important. Other useful
bleaching agents are, for example, peroxycarbonate
(Na2CO3 1.5H2O2) or peracidic salts of organic acids, such
as perbenzoates or salts of diperdodecanedioic acid.
Suitable bleach activators for these oxidizing agents
are, in particular, the N-acyl and O-acyl compounds which
form organic peracids with H2O2, preferably N,N'-tetraacy-
lated diamines, such as N,N,N',N'-tetraacetyl ethylenedi-
amine. The content of oxygen-based oxidizing agents in
the dishwashing detergents is preferably between about 5%
by weight and 15% by weight, more particularly in com-
bination with 1% by weight to 10% by weight and, more
particularly, 2% by weight to 5% by weight of a bleach
activator.
The total surfactant content of the detergents is
generally between 0.5% by weight and 5% by weight and may
advantageously be between 0.8 and 3% by weight. Typical
surfactants for detergents belong to the groups of
anionic, nonionic and/or zwitterionic surfactants, the
use of anionic and/or nonionic surfactants being prefer-
red. Suitable anionic surfactants are, in particular,
sulfonates and sulfates and also soaps of preferably
natural fatty acids or fatty acid mixtures. Suitable
surfactants of the sulfonate type are, for example, C9l3
alkyl benzene sulfonates, olefin sulfonates, esters of ~-
sulfofatty acids or ~-sulfofatty acid disalts. Suitable
surfactants of the sulfate type are the sulfuric acid
monoesters of primary alcohols of natural or synthetic
origin, i.e. of Cl2l8 fatty alcohols or of Cl020 oxoal-
cohols, and those of secondary alcohols with the same
chain length. The sulfuric acid monoesters of alcohols
reacted with 1 to 6 moles of ethylene oxide (EO) are also
suitable.
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WO 94/05762 7 PCT/EP93/02252
Suitable nonionic surfactants are, above all,
addition products of, preferably, 2 to 20 moles of EO
with 1 mole of an aliphatic compound essentially contain-
ing 10 to 20 carbon atoms from the group of alcohols,
carboxylic acids, fatty amines, carboxylic acid amides
and alkane sulfonamides. In addition to water-soluble
nonionic surfactants, however, water-insoluble or sub-
stantially water-insoluble polyglycol ethers containing
2 to 7 ethylene glycol ether units in the molecule are
also important, particularly when they are used together
with water-soluble nonionic or anionic surfactants. In
addition, alkyl polyglycosides corresponding to the
general formula R-0-(G)x, where R is a primary, linear or
branched aliphatic radical containing 8 to 22 and prefer-
ably 12 to 18 carbon atoms, G is a glycose unit contain-
ing 5 or 6 carbon atoms and the degree of oligomerization
x is between 1 and 10, may also be used as nonionic
surfactants.
In one preferred embodiment, the dishwashing deter-
gents according to the invention contain no more than 10%
by weight of water-soluble organic complexing agents or
cobuilders from the group of synthetic polymeric poly-
carboxylates, which are understood to be the salts of
polymerization products of unsaturated carboxylic acids
and which include, for example, polyacrylates, polymeth-
acrylates, polymaleates or copolymers of acrylic acid
with maleic acid or maleic anhydride. Substances such as
these are preferably absent altogether from the deter-
gents according to the invention. In another preferred
embodiment of the detergents according to the invention,
other complexing agents, such as citric acid or alkali
metal citrates and/or the salts of nitrilotriacetic acid,
are absent or are present at most in quantities of not
more than 30% by weight and, in particular, not more than
10% by weight.
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Wo 94/05762 8 PCT/EP93/02252
Besides alkali metal carbonates, alkalizing agents
typically used in solid dishwashing detergents are alkali
metal silicates, preferably sodium silicates, more
particularly amorphous sodium silicates with a molar
ratio of Na20 to SiO2 of 1:1.5 to 1:2.5. Amorphous alkali
metal silicates such as these are commercially available,
for example, under the name of Portil~. The content of
alkali metal silicates in the detergents according to the
invention may be up to 30% by weight, based on anhydrous
substance. Contents of amorphous sodium silicate below
20% by weight and, more particularly, between 5% by
weight and 15% by weight are preferred. Alkali metal
carbonate is preferably present in quantities of 10% by
weight to 60% by weight and, more preferably, in quanti-
ties of 20% by weight to 40% by weight in the detergents
according to the invention, the carbonate being at least
partly replaceable by hydrogen carbonate of which the
content is then preferably 30% by weight to 50% by
weight, based on the detergent as a whole.
The other detergent ingredients mentioned above,
which normally are present in only small quantities, may
make up in particular as much as 20% by weight and
preferably make up from 5 to 10% by weight. These minor
components include, for example, other organic builder
components, foam inhibitors and enzymes of the protease,
amylase, lipase and/or cellulase type and also water
which is not bound as water of crystallization or associ-
ated with the constituents in similarly solid form. The
enzymes may be adsorbed onto supports and/or encapsulated
in shell-forming substances in the usual way and are
preferably used in total quantities of not more than 5%
by weight and, more particularly, between 2 and 4% by
weight. Suitable non-surface-active and preferred foam
inhibitors are organopolysiloxanes and mixtures thereof
with microfine, optionally silanized silica. The foam-
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WO 94/05762 9 PCT/EP93/02252
inhibiting use of long-chain soaps is also possible.
Mixtures of various foam inhibitors, for example mixtures
of silicones and paraffins or waxes, may also be used.
These foam inhibitors are preferably fixed to a granular
water-soluble or water-dispersible support.
The solid, pourable dishwashing detergents according
to the invention are preferably present as powder-form,
granular or tablet-like preparations which may be pro-
duced by methods known per se, for example by mixing,
granulation, roller compacting and/or spray drying.
To produce the detergents according to the invention
in tablet form, all the constituents are preferably mixed
together in a mixer and the resulting mixture is tablet-
ted in conventional tablet presses, for example eccentric
presses or rotary presses, under pressures of 200-105 Pa
to 1,500 105 Pa. Breaking-resistant tablets which still
dissolve sufficiently quickly under in-use conditions
with flexural strengths of normally more than 150 N are
readily obtained in this way. A tablet produced in this
way preferably weighs between 50 g and 40 g and more
preferably between 20 g and 30 g for a diameter of 35 mm
to 40 mm.
The production of the machine dishwashing detergents
in accordance with the invention in the form of dust-
free, storable free-flowing powders and/or granules with
high apparent densities of preferably 750 to 1,000 g/l is
characterized in that, in a first process step, the
builder component is mixed with at least part of the
liquid components to form a premix of increased apparent
density, after which the other constituents of the
machine dishwashing detergent are combined with the
premix, if desired after intermediate drying.
The surfactant compounds liquid under normal condi-
tions, i.e. in particular the corresponding nonionic
surfactants, and optionally other liquid components of
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WO 94/05762 10 PCT/EP93/02252
the formulation as a whole are used as the liquid phase
in the first stage of the process. The other liquid com-
ponents in question are the fragrances dissolved in
carrier liquids and/or limited quantities of water or
aqueous solutions of mixture components of the dishwash-
ing detergent to be produced.
In the first stage of the mixing process according
to the invention, the builder - generally in admixture
with at least one other component of the dishwashing
detergent - is impregnated with the liquid components.
For example, the builder component in admixture with
perborate may be impregnated and thoroughly mixed with
the liquid nonionic surfactants and the solution of
fragrances in the first stage. The remaining components
are then added and the mixture as a whole is compounded
and homogenized in the mixer. In general, there is no
need at this stage to use additional quantities of
liquid, i.e. additional water. The mixture obtained is
a free-flowing powder which does not emit any dust and
which has the required high apparent densities, for
example of 800 to 900 g/l.
In another embodiment, importance is attached to
relatively intensive agglomeration to form heavy agglom-
erate particles. To this end, it may be useful or neces-
sary to use relatively large quantities of liquid so thatalready relatively large quantities of the components to
be combined may be premixed together with the builder
component. For example, the builder component may be
mixed with alkali metal carbonate and at least part of
the fine-particle solid alkali metal silicate and com-
pactingly agglomerated by addition of limited quantities
of water and/or aqueous alkali metal silicate solutions.
If, for example, a Lodige plowhsare mixer with a circular
blade is used, heavy granules with apparent densities of
up to 950 g/l are obtained where the procedure described
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in detail in the following Examples is adopted.
If, in this granulation process, water is used as an
auxiliary liquid in such quantities that the residual
moisture content of the end product exceeds about 4 to 7%
by weight, it can be useful to subject the pregranules
formed to intermediate drying. For example, fluidized-
bed drying is suitable for this purpose. In general,
drying such as this with material temperatures of the
order of 80C for a limited period (for example 10 to 15
minutes) is sufficient to establish the required residual
moisture content of around 4 to 7% by weight in the
product.
The pregranules are then mixed with the missing
components of the dishwashing detergent to form the end
product. In all the cases illustrated herein, the mixing
time is of the order of a few minutes, for example from
1 to 5 minutes, both in the preliminary stage of compact-
ing mixing under the influence of liquid components and
in the subsequent final mixing with the other components.
In one particular embodiment, it can be useful in
the production of fine granules to achieve further
stabilization and equalization by dusting the surface of
the granules formed with a powder, small quantities of
waterglass powder or powder-form alkali metal carbonate
being particularly suitable for this purpose.
E x a m p l e s
Example 1:
Preparation of the oxidized polyglucosans
275.2 g of potato starch (1.6 moles, based on one
anhydroglucose unit) with a moisture content of around 6%
by weight were suspended in 825 g of carbon tetrachloride
and the resulting suspension was transferred to a 2 liter
stirred autoclave. After the autoclave had been evacu-
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WO 94/05762 12 PCT/EP93/02252
ated and purged with nitrogen, 73.6 g of condenseddinitrogen tetroxide (0.8 mole) were added. The reaction
mixture was heated to 50C over a period of 30 minutes.
The internal pressure in the autoclave was 0.5 bar
(adjusted with nitrogen). By introducing oxygen under
pressure, an internal pressure of 2 bar was maintained
for the first hour of the reaction, being increased to 6
bar over the next hour. After a reaction time of 4.5
hours, there was no further consumption of oxygen (re-
flected in the fall in pressure). The autoclave wascooled to room temperature, vented and 1 liter of demin-
eralized water added to the reaction mixture. The
suspension of the oxidation product was filtered through
a glass filter nutsche. The product was washed first
with acetone and then with water until the washing liquid
showed a neutral reaction, freed from water with acetone
and dried (70C, vacuum drying cabinet). 256 g of a
white powder-form polycarboxylate Bl with an acid value
of 324, corresponding to an average content of around 1
carboxyl group per anhydroglucose unit, were obtained.
The product had a reduced viscosity (~red) of 3 ml/g, as
measured on a 2% by weight solution of the sodium salt in
1 N aqueous sodium nitrate solution at 20C.
ExamPle 2
The raw materials listed in Table 1 below were mixed
in the quantities shown (% by weight, based on the final
detergent) in a Lodige mixer with a circular blade.
Detergents Dl to D6 according to the invention were
obtained using the polycarboxylate Bl produced in accord-
ance with Example 1, detergents Cl and C2 being intended
for comparison.
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Table 1:
Composition of the detergents (% by weight)
D1 D2 D3 D4 D5 D6 C1 C2
Bl 30 30 8 10 30 30 - -
Na citratea) - -3 0 3 0 - -3 0 3 0
Polycarboxylateb) 8 - - - 10 - 8 10
Na disilicate 20 20 20 - - - 20
Na carbonate 30 38 30 13 13 13 30 13
Na hydrogen carbonate - - - 36 36 46 - 36
Na perborate ) 7 7 7 5 5 5 7 5
TAED 2 2 2 2 2 2 2 2
Nonionic surfactant ) 2 2 2 1 1 1 2
Enzymee) 1 1 1 3 3 3 1 3
a) Trisodium citrate dihydrate
b) Na Poly(acrylate/maleate) (Sokalan~ CP 5, a product
of BASf)
C ) Monohydrate
d) Plurafac~ LF 403 (a product of BASF)
e) 1:1 mixture of protease (BLAP~ 140, a product of
Biozym) and amylase granules (Termamyl~ 60 T, a
product of Novo)
Example 3
The detergents according to Example 2 were perform-
ance-tested in the wash cycle of a dishwashing machine
(Miele G531; program Universal 55) in quantities of 20 g
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WO 94/05762 14 PCT/EP93/02252
in 7 liters of water with a hardness of 16dH (soils as
described in Th. Altenschopfer, SOFW 98 (1972) 763-765:
tea, milk, minced meat, pudding, grease stick, starch,
oatflakes). Detergents Dl to D6 according to the inven-
tion showed superior performance, particularly in theremoval of the starch and oatflake soils, and were
comparable in performance with comparison detergents C1
and C2 in regard to the removal of the other soils.
The detergents according to Example 2 were tested
for bloom formation over ten rinse cycles in a Bosch S
712 dishwashing machine (detergent dosage 20 g in 6.2
liters of water with a hardness of 16dH, operating
temperature 50C) with addition of 50 g of pumpable soils
(mixture of ketchup, gravy, mustard, potato starch, egg
yolk, milk, margarine). On a scale of 1 (= no bloom) to
10 (= very heavy bloom), detergents D1 to D3 according
to the invention achieved the scores shown in Table 2
below for bloom formation in the machine (score A) and
for bloom formation on the machine load (china/glass/
cutlery; score B). In every case, these scores were
significantly better than the scores achieved by com-
parison detergent Cl. Similarly, the scores achieved by
detergents D4 to D6 were significantly better than the
scores of the similarly formulated comparison detergent
C2.
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Table 2:
Bloom formation using the detergents
Detergent Bloom A Bloom B
Dl n.d. 6.5
D2 6.0 4.5
D3 5.0 3.5
D4 3.5 4.0
D5 5.5 4.5
D6 3.0 3.0
Cl 6.5 7.0
C2 6.0 5.8
n.d.: not determined
