Note: Descriptions are shown in the official language in which they were submitted.
~ 10769~
This invention relates to the washing of textiles (as herein de-
fined) with an aqueous detergent-containing bath whose detergent substanti-
ally comprises at least one organic anionic, non-ionic, ampholytic, or ampho-
teric surfactant, an alkali metal tripolyphosphate ~which may be a technical
grade) as water-soluble builder, and a finely divided alkali metal aluminium
silicate as water-insoluble builder, with or without one or more additional
detergent adjuvants. The word "textiles" is employed herein in a broad sense;
thus it includes knitted fabrics and non-woven fabrics, and also textile
fibres, filaments, rovings and yarns, in addition to woven fabrics.
It is known that the washing and cleaning power of soaps and syn-
thetic surfactants can be increased by the addition of certain substances
known as builders.
The mechanism and precise nature of the action of these builders
have not yet been completely elucidated, so that a prediction based on theo-
retical principles as to which types of compound could be suitable for this
purpose is not yet possible.
Having regard to the multiplicity of individual effects which can
cooperate in increasing the washing power of surfactants, we consider that
the requirements which must be imposed on a builder in the light of present
knowledge are that the builder should be capable of:
1. forming water-soluble complexes with hardness-producing salts
present in the water being used, e.g. with calcium and mag-
nesium ions;
2. dispersing, in the washing bath, pigmentary soil particles
representing a principal component of the soil carried by the
textiles being washed;
3. stabilising detached soil in the washing bath in order to
prevent soil particles from being redeposited upon by the
textiles being washed;
4. inactivating any mineral constituents present in the washing
bath;
5. reducing the adsorption of surfactants on the textiles being
washed.
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In order to obtain information regarding the efficiency and suit-
ability of particular products as builders, it is appropriate to determine
their behaviour and efficiency in the washing process itself. It is thereby
ensured that all factors affecting the builder action are taken into account,
qualitatively and quantitatively.
Known builders comprise water-soluble alkali metal salts of mineral
acids, e.g. alkali metal carbonates, borates, phosphates, polyphosphates, bi-
carbonates, and silicates.
Among known builders a preferential position is occupied by the alk-
ali metal polyphosphates, since these fulfil all the requirements indicated
above, and exhibit, during washing, synergistic effects in combination with
surface-active substances. Consequently they constitute at the present time
the most important builders in light-duty, heavy-duty, and coloured-wash de-
tergents. For this purpose pentasodium triphosphate is mainly used. The con-
tent of this builder in detergents is commonly 25 to 65%, and in certain pre-
parations this content is up to 90% by weight.
Because of the recent considerable increase in the consumption of
phosphate-containing detergents and cleaning agents, both in the household
field and in industry, the proportion of these phosphates present in natural
waters has correspondingly increased. In discussions of the causes of the in-
creasing eutrophication of waters, the water-soluble nitrate and phosphate
salts have recently been said to possess the property of promoting the growth
of certain species of algae under certain conditions and thus contributing
towards the eutrophication of waters, whereby their oxygen balance is dis-
turbed. Although at the present time it is not yet possible to make a def-
initive assessment of the part played by phosphate-containing washing and
cleaning agents in the eutrophication of waters, nevertheless it appears to be
desirable to make available substitutes, containing no nitrogen or phosphates,
for the builders used hitherto in detergent formulations; or alternatively, by
blending alkali metal polyphosphates with certain other detergent components,
to effect a reduction in the phosphorus contents of detergent formulations.
In this connection various organic compounds have already been
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proposed as builders, for example nitriloacetic acid, ethylene-diaminetetra-
acetic acid, citric acid, oxydiacetic acid, oxydisuccinic acid, cyclocarboxyl-
ic acids, and polymeric carboxylic acids, e.g. polymers of maleic acid and
acryl:ic acid, and their copolymers with other unsaturated carboxylic acids,
olefins, or short-chain unsaturated aliphatic ethers or alcohols.
The substances mentioned above have not proved to be satisfactory
builders in every respect, however, inasmuch as they (1) have a strong ten-
dency to form complexes with heavy metals and transition metals, so that in-
creased contents of these metals are found in surface waters (whether as the
result of direct sequestration or subsequent remobilisation of flow sedi-
ment) and may pass into drinking water; or (2) do not to an adequate extent
possess the previously mentioned properties of a builder, so that they do not
give satisfactory washing results; or (3) are not sufficiently biodegradable.
It has recently been recognised that, by virtue of their ion ex-
change capacity, the water-insoluble alkali metal aluminium silicates are also
suitable for replacing part of the sodium tripolyphosphate in detergent form-
ulations, and thus reducing the total phosphate content of the detergent. On
completion of the washing process, these water-insoluble builders can readily
be separated from the washing bath, but even if they are discharged in the
waste water they do not give rise to any biologically undesirable loading of
surface-waters, unlike the known organic builders.
A method of washing (e.g.) textiles in the presence of water-insol-
uble alkali metal aluminium silicates, these being employed in conjunction
with commonly used detergent components, has been described in German Pub-
lished Specification ("Offenlegungsschrift") No. 2,412,837. The proportion
of metaphosphates and polyphosphates in these detergent formulations is so
regulated that the maximum phosphate content in the washing bath amounts to
0.6 gram of phosphorus per litre of washing bath. According to the examples
given in this German Specification, 2.5 to 29.2 parts by weight of pentasodium
triphosphate and 45 to 11.3 parts by weight of sodium aluminium silicate hav-
ing a calcium sequestering power of 150 mg of CaO per gram of silicate would
be employed per 100 parts by weight of detergent.
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The advantages attributed in the above-mentioned German Specifi-
cation to the use of a blend of sodium tripolyphosphate and sodium aluminium
silicate or sodium borosilicate in detergent formulations apply only to what
is ca]led the primary washing action; this represents only a measure of the
brightening effect achieved for an artificially soiled test fabric. In prac-
tice, however, it has been found that what is called the secondary washing
action of the detergent formulation, this being defined by the degree to which
the fabric is loaded or "encrusted", is unsatisfactory. Nevertheless, in
judging a washing process, the secondary washing action is of importance as
well as the primary washing action. Heavily loaded or "encrusted" laundry
loses some of its usefulness inasmuch as its absorptivity is reduced, it wears
more rapidly, and it becomes less attractive because of its hard rough feel.
Another disadvantage of this prior detergent formulation results from the en-
crustation occurring during the washing process on the heating elements in
the washing machine used. Encrusted heating elements increase the energy cost
of the washing process, and tend to necessitate unduly early servicing or
replacement of the washing machine.
We have now found, to our surprise, that the disadvantages of the
detergent compositions of the above-mentioned German Specification can be
overcome if one ensures that the proportion of alkali metal mono- and/or di-
phosphate(s3 in the washing bath is not more than 0.1 gram per litre. The
presence of this alkali metal mono- or diphosphate in the washing bath results
from the method of production of the alkali metal tripolyphosphate or of the
detergent composition as a whole. If the proportion just mentioned is duly
kept to 0.1 gram per litre or less, contents of approximately 0.5 to 2 grams
of alkali metal tripolyphosphate and approximately 0.5 to 4 grams of alkali
metal aluminium silicate per litre of washing bath are sufficient to obtain
satisfactory primary and secondary washing actions.
In ordinary commercially available technical grade alkali metal
tripolyphosphates, the proportion of alkali metal mono- and/or diphosphate(s)
present may be as much as 20% by weight, according to which production pro-
cess is employed. Moreover, if the detergent composition is produced by the
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hot spray drying process, which is very commonly employed, the content of
alkali metal mono- and/or diphosphate~s) is additionally increased, in some
cases to a considerable extent, by hydrolysis occurring during the prepara-
tion of the slurry, and by pyrolysis of the tripolyphosphate during the hot
spray drying; thus the final product may contain considerable proportions of
mono- and/or diphosphate(s). Alkali metal mono- and diphosphates form in-
soluble precipitates with calcium and magnesium ions present in the washing
water, unless these hardness-producing ions are rendered ineffective by
suitable measures. Ordinary detergent compositions which are produced with
the use of ordinary commercial sodium tripolyphosphate by the methods of the
prior art do give satisfactory washing results, despite their contents of ,
alkali metal mono- and/or diphosphate(s), because the content of the ordinary . -
commercial sodium tripolyphosphate in the detergent composition is sufficient-
ly high to ensure after the complexing of the calcium and magnesium ions has
taken place, an excess of sodium tripolyphosphate is still available in the
washing process, so that the precipitation of alkali metal mono- and/or di-
phosphate(s) is avoided even at washing temperatures up to 90C. When deter-
gent compositions according to the above-mentioned German Specification
having a reduced alkali metal tripolyphosphate content are used, however, the
precipitation of salts having an encrusting action naturally cannot be pre-
vented.
According to the present invention, therefore, there is provided
in the process of washing textiles by treating the textiles with an aqueous
detergent-containing bath at a temperature of about 20 to 95C, wherein the
detergent substantially contains an organic anionic, non-ionic, ampholytic
or amphoteric surfactant, an alkali metal tripolyphosphate contaminated with
alkali metal mono- or diphosphates as water-soluble builder, a finely divided -
alkali metal aluminium silicate having a particle size of at most 40 u and
a calcium sequestering power of at least 5 g Ca per 100 g of dehydrated
silicate as water-insoluble builder, and optionally additional washing adjuvantsand wherein the bath contains the organic detergent in an amount of about 0.3
to about 1 g per litre of improvement consisting in that with a content of
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about 0.5 to 2 g of alkali metal tripolyphosphate and about 0.5 to 4 g of
alkali metal aluminium silicate in one litre of washing bath the latter
simultaneously contains at most 0.1 g of alkali metal mono- or diphosphate
per litre.
In a preferred form of the process of the invention the silicate
should have a calcium sequestering power of approximately 10 to 14 grams of
Ca per 100 grams of silicate. The alkali metal aluminium silicate may for
example be represented by a crystalline zeolite which in its unactivated form
substantially contains 18.2% Na20, 30.8 % A1203, 34.1 % SiO2 and 16.7 % H20,
the balance being impurities.
The washing bath employed in the process of the invention may addi-
tionally contain one or more of the following detergent adjuvants: sodium
silicate; magnesium silicate; carboxymethylcellulose; sodium perborate tetra-
hydrate; ethylenediaminetetraacetic acid, sodium sulphate, and mixtures there-
of.
The surfactants which may be employed in the process of the inven-
tion broadly comprise anionic, amphoteric, ampholytic, and non-ionic
surfactants.
The "anionic" surfactants are to be understood to include water-
soluble salts of higher fatty acids or resin acids, e.g. sodium or potassium
soaps of hardened or unhardened coconut palm oil or rapeseed oil and also
tallow and mixtures thereof. Also these anion-active substances which may be
employed in the process of the invention are to be understood to include salts
of higher-alkyl-substituted mononuclear aromatic sulphonates, e.g. alkyl-
benzene sulphonates having 9 to 14 carbon atoms in the alkyl radical, alkyl
naphthalene sulphonates, alkyl toluene sulphonates, alkyl xylene sulphonates,
or alkylphenol sulphonates, and also salts of sulphated aliphatic alcohols
or alcohol ethers, e.g. sodium or aluminium lauryl or hexadecyl sulphate,
triethanolamine lauryl sulphate, sodium or potassium oleyl sulphate, and also
sodium or potassium salts of lauryl sulphate ethoxylated with (e.g.) 2 to 6
moles of ethylene oxide. Other suitable anionic surfactants are secondary
linear alkane sulphonates and also alpha-olefin sulphonates having a chain
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1~76914
length of 12 to 20 carbon atoms.
The non-ionic or non-ionogenic surfactants which may be employed in
the present process are to be understood to include non-ionogenic compounds
which contain an organic hydrophobic group and also a hydrophilic radical.
Examples of non-ionogenic surfactants are: condensation products of alkyl
phenols with ethylene oxide, or of higher fatty alcohols with ethylene oxide;
condensation products of polypropylene glycol with ethylene oxide or propy-
lene oxide; condensation products of ethylene oxide with a product of a
reaction between ethylene diamine and propylene oxide; long chain tertiary
amine oxides.
The ampholytic or zwitterionic surfactants which may be employed in
the process of the invention include: derivatives of aliphatic secondary
and tertiary amines or quaternary ammonium compounds containing 8 to 18 carbon
atoms and having a hydrophilic group in the aliphatic radical, e.g. sodium-3-
dodecylaminopropionate, sodium-3-dodecylaminopropane sulphonate, 3-(N,N-di-
methyl-N-hexadecylamino)propane-l-sulphonate; fatty acid amino alkyl-N,N-
dimethylacetobetaines, the fatty acid containing 8 to 18 carbon atoms and the
alkyl radical containing 3 carbon atoms.
Detergent adjuvants (additives) which may be employed in the process
of the invention include the following, for example: alkali metal or ammonium
salts of sulphuric acid, silicic acid, carbonic acid, boric acid, or an
alkylene-hydroxyalkylene- or amino alkylene phosphonic acid; bleaching agents;
stabilisers for peroxide compounds; water-soluble organic complexing agents.
More specifically, use may be made of: sodium perborate mono- or
tetrahydrate; alkali metal salts or peroxymono- or disulphuric acid; alkali
metal salts of perpyrophosphoric acid; precipitated water-insoluble magnesium
silicate, alkali metal salts of iminodiacetic acid, nitrilotriacetic acid,
ethylene diaminetetraacetic acid, methylene diphosphonic acid, hydroxyethane
diphosphonic acid, or nitrilotrismethylene phosphonic acid.
Use may also be made of: substances which increase the soil-
suspending power of washing baths, e.g. carboxymethylcellulose polyvinyl
alcohol or polyvinylpyrrolidone; foam regulators, e.g. mono- or dialkyl phos-
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10769~4
phoric esters containing 16 to 20 carbon atoms in the alkyl radical; optical
whitening agents; disinfectants; proteolytic enzymes. Detergent adjuvants
(additives) which when employed with the other consitutents of the washing
bath contribute towards an improvement of the detergent effect include in
partic:ular: magnesium silicate; sodium silicate; sodium perborate tetra-
hydrate; sodium sulphate; carboxymethylcellulose.
The detergent compositions having a low alkali metal mono- and/or
diphosphate content which are suitable for use in preparing the washing bath
employed in the process of the invention can for example be produced by the
use of sodium tripolyphosphate which either has been purified by recrystal-
lisation or has been produced from thermal phosphoric acid by a single-stage
hot spray method, and which has an active pentasodium triphosphate content
of at least 95 %, this tripolyphosphate being utilised in a hot spray drying
process for the production of a detergent composition; it is also possible to
use at least 90 % sodium tripolyphosphate in the production of the detergent
composition by a dry mixing method. In this latter case there are no losses
of sodium tripolyphosphate through hydrolysis and pyrolysis in the production
of the detergent composition.
The invention is illustrated by the following example; however, it
is not restricted thereto.
EXAMPLE
In order to determine the influence of tetrasodium diphosphate on
the secondary washing action of blends of sodium tripolyphosphate and sodium
aluminium silicate, washing tests were carried out in a domestic washing
machine of the Miele 416 S type, using natural industrial water of 18dH.
The detergent components used were:
a) constant amounts of a basic detergent preparation, together with
b~ variable amounts of sodium tripolyphosphate, tetrasodium di-
phosphate, and sodium aluminium silicate.
The basic detergent preparation had the following composition:
7% by weight of dodecylbenzene sulphonate;
3% by weight of tallow fatty alcohol ethoxylate containing 11 moles
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1~7691~
of ethylene oxide per mole of tallow fatty alcohol;
3% by weight of hardened tallow soap;
4% by weight of magnesium silicate;
3% by weight of sodium silicate;
1% by weight of carboxymethylcellulose;
25% by weight of sodium perborate tetrahydrate;
0.2% by weight of ethylenediaminetetraacetic acid;
8% by weight of water; and
sodium sulphate to make 100% by weight.
The sodium tripolyphosphate used in the washing tests was obtained
by recrystallisation of technical sodium tripolyphosphate, the purity of which
amounted to 94.2 %, in accordance with the information given by O.T. Quimby
in J. Phys. Chem. 58 (1954) page 603. The purified sodium tripolyphosphate
still contained 0.1 % by weight of disodium hydrogen phosphate and 0.2 % by
weight of tetrasodium diphosphate.
The tetrasodium diphosphate used in the washing tests was a commer-
cial product and still contained 1 % by weight of disodium hydrogen phosphate
and also 0.5 % by weight of sodium tripolyphosphate.
The sodium aluminium silicate used was a finely divided crystalline
zeolite of the "molecular sieve A" type. The exchange capacity of this
product for Ca ions at 90 C was 14 g of Ca per 100 g of substance.
Molecular sieve A had the following composition:
18.2 % By weight of Na20, 30.8 % by weight of A1203, 34.1 % by
weight of SiO2, and 16.7 % by weight of H20. The mole ratio amounted to 0.97
Na20 . A1203 . 1.9 SiO2 . 3.1 H20. The maximum particle size of the molecular
sieve A was 40 ~
The dosage of the basic detergent preparation in the washing bath
amounted to 5 grams per litre of washing bath for each washing test. The
amount of the other components of the detergent varied, as can be seen from
the Table below. The washing tests were carried out in accordance with the
washing programme for a boiling wash with prewash and clear wash. The maximum
temperature in the prewash stage was 40C and in the clear wash stage about
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85 to 90C. Following the clear wash the material washed was rinsed five
times and subjected to a new washing cycle without intermediate drying, since
in preliminary tests no difference was found in the washing results when the
goods washed were previously dried in the clothes dryer.
Based on the procedure proposed by Schweizerische Gesellschaft
fUr analytishe und angewandte Chemie in "Seifen und Waschmittel", Berne,
1955, page 116, unsoiled "Renforcé" cotton fabric of Eidgenossische Material-
prufungsanstalt ~Federal Material Testing Institute) of St. Gallen,
Switzerland, was used as test fabric and ballast, in stitched strips of 40 x
80 cm. The weight of the fabric amounted to 1.2 kg, so that there was a bath
ratio of 1:12.5. After 50 washing cycles, the fabric was washed at 900C and
the encrustation of the fabric was ascertained as percentage of ignition
residue. After 50 washing cycles, the heating bar elements were also examined
for encrustation, for which purpose they were removed from the washing machine.
The results obtained in the individual series of tests, each comprising 50
washing cycles, are shown in the Table.
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TAsLE
Test Dosage of detergent components (g/l)
Series
No. I II III IV V VI
1 5 2 0 0 7.6 heavy
2 5 1 1 0 3.4 light
3 5 1 1 0.05 3.8 light
4 5 1 1 0.1 4.6 light
1 1 0.15 6.7 medium
6 5 1 1 0.3 7.8 heavy
7 5 2 1 0 2.2 light
8 5 2 1 0.1 2.4 light
9 5 2 1 0.3 3.8 heavy
4 1 0 1.4 light
11 5 4 1 0.1 1.6 light
12 5 4 1 0.3 2.2 medium
13 5 1 2 0 0.8 none
.
14 5 1 2 0.1 0.9 none
1 2 0.4 1.9 medium
16 5 0 1 0 10.8 heavy
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10769i4
The column headings in the Table should be interpreted as follows:
Column I: Amount of basic detergent preparation in grams per
litre of washing bath.
Column II: Amount of sodium aluminium silicate (molecular sieve
A) in grams per litre of washing bath .
Column III: Amount of sodium tripolyphosphate in grams per litre
or washing bath.
Column IV: Amount of tetrasodium diphosphate in grams per litre
of washing bath.
Column V: Loading of fabric after 50 washing cycles in ~%).
Column VI: Encrustation of heating bars after 50 washing cycles
in (%).
The series of experiments 2-4, 7, 8, 10, 11, and 14 correspond to
the process of the invention, while the other series of experiments serve for
comparison. From the Table it can be seen that the washing tests carried
out under the washing conditions of the invention result in substantially less
loading of the fabrics washed and substantially less encrustation of the
heating bar elements of the washing machine than in the comparison tests.
The process of the invention can thus be said to be a technical improvement
in relation to the process of DT OS 2,412,837.
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