[0001] The present invention relates to fabric washing processes and to the compositions
which are adapted for this purpose, using synthetic detergent active compounds together
with phosphate detergency builders. The invention concerns in particular fabric washing
using detergent compositions which contain levels of the phosphate detergency builders
which can be lower than conventional phosphate builder levels; whilst still achieving
good detergency results.
[0002] It is known to include tripolyphosphates as builders in detergent compositions. In
US 4 113 644 (Ashcraft) there is described a detergent composition containing both
orthophosphate and tripolyphosphate in addition to high levels of alkalimetal pyrophosphate.
[0003] A detergent dishwashing composition is known from GB 1 224 777 (Armour) which is
intended for use at substantially neutral pH and which contains in addition to an
acid orthophosphate, encapsulated sodium tripolyphosphate with the object of providing
good cleaning action over an extended period of time.
[0004] It is also known to wash fabrics in two steps. Thus GB 996 193 (Henkel) describes
adding a first concentrate to water to form a wash liquor and subsequently adding
a second concentrate to the same liquor. By suitable choice of components in these
concentrates, enhanced bleaching of fabrics can be obtained.
[0005] The present invention on the other hand is concerned with low phosphorus containing
compositions having enhanced building properties.
[0006] According to a first aspect of the invention there is provided a process for washing
fabrics comprising the steps of:
( i) contacting the fabrics with a wash liquor containing a synthetic detergent active
compound and an alkalimetal or ammonium orthophosphate; and
(ii) subsequently contacting the fabrics with a wash liquor containing a synthetic
detergent active compound and an alkalimetal or ammonium tripolyphosphate, each of
said wash liquors having a pH between about 8 and about 12 and each of said wash liquors
containing substantially no alkalimetal pyrophosphate.
[0007] The process can be conducted if desired in two stages, for example using a prewash
as step (i) and then a main wash as step (ii), the fabrics being substantially separated
from the prewash liquor before being contacted with the main wash liquor. In this
event there is often some carry-over of the ingredients in the pre-wash into the main
wash, so that there is some benefit from the presence of residual alkalimetal orthophosphate
in the main wash liquor. Many modern domestic washing machines are designed for sequential
pre- and main washes, or the consumer may himself arrange the sequential washing.
[0008] Alternatively, the washing process can be conducted in a single stage, where the
liquor used in step (i) remains in contact with the fabrics during step (ii). This
can be achieved by including the tripolyphosphate together with the orthophosphate
and synthetic detergent compound in a single composition, but treating the former
to delay its dissolution so that in step (i) it remains in an undissolved form, or
by adding the tripolyphosphate to the wash solution later than the other ingredients.
This can again be achieved manually or automatically. Dissolution of the tripolyphosphate
is desirably delayed for at least 15 seconds, preferably at least one and especially
at least 5 to 30 minutes, or even more after dissolution of the bulk of the orthophosphate,
to encourage maximum precipitation of calcium orthophosphate before addition of the
former.
[0009] According to a second aspect of the invention there is provided a detergent composition
for carrying out such a method, comprising a synthetic detergent active compound,an
lakalimetal or ammonium orthophosphate and an alkalimetal or ammonium tripolyphosphate
characterised by means for delaying the solubility of said alkalimetal or ammonium
tripolyphosphate when the composition is added to water to form a wash liquor, said
composition yielding a pH of between about 9 and about 11 when dissolved in 120H(Ca)
water at 50
0C and at a concentration of 0.1% w/v, and said composition containing substantially
no alkalimetal pyrophosphate.
[0010] The detergent composition may be in the form of two containers, the first container
containing at least a part of said synthetic detergent active compound and the . orthophosphate
and the second container containing the alkalimetal or ammonium tripolyphosphate and
optionally a further part of the synthetic detergent active compound. In use, the
contents of the first container are released into water to form a wash liquor for
step (i) of the process and subsequently the contents of the second container are
released to form a wash liquor for step (ii) of the process.
[0011] The delayed addition of the tripolyphosphate to the washing solution is advantageous
in giving decreased deposition of inorganic phosphates on the washed fabric, compared
with the simultaneous addition of the tripolyphosphate and orthophosphate. It is believed
that this ia due to the substantially complete precipitation of calcium orthophosphate
by reaction with hard water before dissolution of the tripolyphosphate. This, in turn,
appears to lead to decreased hydrolysis of the tripolyphosphate, compared with the
amount of hydrolysis which takes place when the water had not been pre-softened in
this way; one of the products of hydrolysis is alkali metal or ammonium pyrophosphate
which apparently causes high levels of inorganic deposition on the washed fabric,
and hence the control of the rate of hydrolysis of the tripolyphosphate as proposed
leads to decreased fabric deposits.
[0012] The washing process of the invention can be accomplished manually, if desired, but
is normally accomplished in a domestic or commercial laundry washing machine. The
latter permits the use of higher wash temperatures and alkalinity, and more effective
agitation, all of which contribute generally to better detergency. High wash temperatures
(at least about 60°C) and high alkalinity (over about pH 10) also particularly assist
the precipitation of the calcium orthophosphate to achieve more effective water softenlng.
However, any wash temperature between ambient and boiling may be employed with any
normal degree of alkalinity (pH 8-12). The type of washing machine used, if any, is
not significant.
[0013] It is preferred to accomplish the washing process in the joint presence of both the
orthophosphate and the tripolyphosphate, but with the dissolution of the latter being
delayed, as described above. This has the advantage of combining the water-softening
action of both phosphates. This means, referring to the process of the invention,
that the first aqueous solution is used to prepare the second aqueous solution. An
added advantage is that the detergent active compound used in both solutions can then
be the same substance or mixture of substances.
[0014] It should be appreciated that when in aqueous solution in hard water, the alkali
metal or ammonium orthophosphate and tripolyphosphate will be present wholly or partially
in the form of the calcium or magnesium salts, which are insoluble for the orthophosphates
and soluble chelates in the case of the tripolyphosphate. But for convenience the
phosphates will be referred to generally as being in the alkali metal or ammonium
salt form as appropriate, as if the aqueous solutions were prepared with de-ionised
water.
[0015] The detergent compositions used in the process of the invention may be either solid
or liquid compositions. Either physical form can be used if the orthophosphate and
tripolyphosphate are included indifferent compositions for separate addition to the
wash liquor. Compositions in liquid form are suitable in particular for commercial
laundry use, in which bulk supplies of aqueous orthophosphate and tripolyphosphate
solutions are available and are automatically dosed to the washing machines at the
appropriate times in the wash cycle. But if the orthophosphate and tripolyphosphate
are included in a single composition, with the latter being treated to delay its solubility,
the composition will normally be in solid form, e.g. as a powdered or granulated product.
[0016] The invention includes processes for the preparation of such detergent compositions
suitable for fabric washing according to the invention, by forming a detergent base
powder containing a detergent active compound or compounds and optionally the alkalimetal
orthophosphate, and admixing with the base powder any further orthophosphate and an
alkalimetal or ammonium tripolyphosphate, treated to delay its dissolution in water.
[0017] Preferably the base powder is prepared by spray drying in the normal way using conventional
equipment and process ! conditions. However, other conventional techniques may be
used for preparing the base powder containing the detergent active compound and usually
the orthophosphate. Other heat-sensitive ingredients may also be admixed with the
base powder together with or separately from the treated alkali metal or ammonium
tripolyphosphate,for example oxygen bleach compounds such as sodium perborate.
[0018] The alkali metal tripolyphosphate used in the compositions of the invention is preferably
sodium tripolyphosphate, but if desired the potassium or ammonium salts can be used.
For convenience the term alkali metal tripolyphosphate is used : below to include
the sodium, potassium and ammonium salts. : The alkali metal tripolyphosphates are
generally represented as haying the formula M
2O(MPO
3)
3 or M
5P
3O
10 where M is sodium, potassium or ammonium.
[0019] If the tripolyphosphate is treated to delay its dissolution, for inclusion in a single
composition with the orthophsophate, this may be accomplished in the production of
the tripolyphosphate or subsequently.
[0020] Specifically, the tripolyphosphates may be made with a large particle size or the
tripolyphosphate may be coated or encapsulated with a slowly soluble material such
as wax, nonionic detergent compounds,higher fatty acids or a protein such as gelatin.,
The rate of solubility of the tripolyphosphate may also be decreased by using them
in partial calcium, zinc or other polyvalent salt form. Two or more of these treatments
may also be combined, so as to give close control over the solubility of the tripolyphosphate
under the recommended washing conditions.
[0021] The rate of solubility of the polymer phosphate may also be controlled by granulating
the tripolyphosphate with sodium silicate. Specifically, the granules may contain
the tripolyphosphate and an alkalimetal silicate having a M
2O:SiO
2 ratio of from about 1:2 to about 1:3.75 wherein M is an alkalimetal, the granule
being dried to a moisture content of less than 7% by weight. A particularly useful
granule of this type can be achieved by granulating 1 part of tripolyphosphate with
3 parts of sodium silicate having an Na
20:Si0
2 ratio of 1:2. The tripolyphosphate- containing granule may also contain a portion
of the synthetic detergent-active compound.
[0022] US 4 040 988 (Benson) describes granules formed by sequestering builders and alkalimetal
silicates and may be referred to in this connection.
[0023] The delayed solubility of the tripolyphosphate may also be achieved by dosing the
composition in a two- compartment sachet, the sachet being so constituted that when
added to water the contents of the first compartment, namely the alkalimetal orthophosphate
and at least some of the synthetic detergent active compound are released before the
contents of the second compartment,.namely the alkalimetal or ammonium tripolyphosphate
and optionally a further part of the synthetic detergent active compound.
[0024] A suitable sachet construction of this type is disclosed in British Patent Application
No 8016242 which may be referred to in this connection. Thus, a sachet may be made
from a first outer sheet of polyethylene film, a second outer sheet of acrylic bonded
polyester/ viscose non-woven fabric and an inner sheet of thermally bonded polypropylene
non-woven fabric, these three sheets being heat-sealed together at the edges to define
a sachet with two compartments. Before sealing the final edge, the first compartment
between the two layers of non-woven fabric may be filled with the orthophosphate and
at least some of the synthetic detergent active compound. The second compartment may
be filled with the alkalimetal or ammonium tripolyphosphate and optionally a further
part of the synthetic detergent acive compound.
[0025] In use the contents of the second compartment are released after those of the first
compartment because they must pass through the first compartment before entering the
wash liquor.
[0026] The solution of the tripolyphosphate may also be delayed by coating or encapsulating
the tripolyphosphate with a water-dispersible water-insoluble material or with a water-soluble
material. Examples of such coating materials include fatty acids, alkanolamindes of
fatty acids, glycerol esters of fatty acids, long chain hydrocarbon aliphatic alcohols,
paraffin waxes, mineral oil, gelatin, sugar, nonionic surface active agents, polycinylalcohol
and sodium carboxymethylcellulose as described in US 3 847 830 (Williams) and GB 1
242 24? (Unilever).
[0027] The orthophosphate used is either potassium or preferably sodium orthophosphate,
as the latter is cheaper and more readily available. Ammonium orthophosphate may also
be used, particularly if the composition is not made by spray drying. Normally the
tri-alkali metal salts are used, but orthophosphoric acid or the di- or mono-alkalimetal
salts, e.d. gisodium hydrogen orthophosphate or monosodium dihydrogen orthophosphate
could be used if desired in the production of the compositions. In the latter event
other more alkaline salts should also be present to maintain a high pH in the end
product, i.e. with full neutralisation to the trialkali metal orthophosphate salts.
The use of a mixture of the monosodium dihydrogen and disodium hydrogen orthophosphates
in the ratio of 1:3 to 2:3, especially about 1:2, is particularly advantageous, as
such a mixture (known as kiln-feed) is made in the production of sodium tripolyphosphate
and is readily available.
[0028] The orthophosphate can be used in the form of the anhydrous or hydrated salts, but
in the former case it is preferred to promote hydration during processing, e.g. by
adding the anhydrous orthophosphate to a detergent slurry and spray drying to form
a base powder. The alkali metal polymer phosphates do not form hydrated salts as such,
and are normally used in predominantly anhydrous form, but they are hygroscopic and
tend to absorb atmospheric moisture. The amounts of salts used are expressed in anhydrous
form.
[0029] The total amounts of the essential tripolyphosphate and orthophosphate, and any other
phosphates which may be present in the detergent compositions, are chosen according
to the overall detergency builder level which is desired in the detergent compositions
or according to the maximum permitted phosphorus content. Normally, when both the
orthophosphate and tripolyphosphate are present in a single composition, the total
phosphate builder level, which is preferably derived solely from the alkali metal
tripolyphosphate and orthophosphate, is between about 5% and about 50%, preferably
about 10% to about 30% by weight of the composition, with an amount of about 2% to
about 20% each of the tripolyphosphate and orthophosphate. Preferably the amounts
of the tripolyphosphate and orthophosphate are each from about 5% to about 15%, especially
about 5% to 10% by weight of the product. The total amount of tripolyphosphate and
orthophosphate is preferably from about 10% to about 25%, especially about 15% to
about 20%, by weight of the composition.
[0030] It is generally preferred to have amounts of the orthophosphate and the tripolyphosphate,
within the ratio of from about 3:1 to about 1:3 especially about 2:1 to about 1:2,
parts by weight. These ratios of tripolyphosphate to orthophosphate are particularly
suitable for detergent compositions used at relatively high product concentrations,
i.e. 0.3% to 0.8% by-weight as is common practice in Europe, especially in front-loading
automatic washing machines, and where moderate levels of phosphates are allowed in
the products, i.e. equivalent to 2% to 7% P.
[0031] It is preferable that the only phosphate detergency builders used in the process
of the invention should be the tripolyphosphate and orthophosphate. In particular,
it is aesirable to use no alkali metal, i.
e. sodium or potassium, pyrophosphates in the compositions as this tends to increase
inorganic deposition as mentioned above.
[0032] Some pyrophosphate is generally found as impurities at low levels in other commercial
alkali metal phosphates, and some pyrophosphate may also be formed by hydrolysis of
any polymer phosphate during processing, for example during slurry making. Hence,
total absence of alkali metal pyrophosphate is generally unattainable in the detergent
compositions. It is particularly preferred to have not more than about 5% especially
not more than about 2.5% of alkali metal pyrophosphate present in the compositions,'as
at higher levels the amounts of inorganic deposits on the washing machine parts become
significantly more noticeable.
[0033] However, some of the tripolyphosphate may be replaced by an alkalimetal or ammonium
polymerphosphate such as is described in our copending application No (
GB 79
37167 Case No C.1052).
[0034] The process of the invention is necessarily accomplished using synthetic anionic,
nonionic, amphoteric or zwitterionic detergent active compound or mixture thereof.
Detergent compositions normally include from about 2.5% to about 50%, preferably about
5% to about 30%, and especially about 10% to about 25% by weight of such ingredients.
Many suitable detergent compounds are commercially available and are fully described
in the literature, for example in "Surface Active Agents and Detergents", Volumes
I and II, by Schwartz, Perry & Berch.
[0035] The preferred detergent compounds which can be used are synthetic anionic and nonionic
compounds. The former are usually water-soluble alkali metal salts of organic sulphates
and sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms,
the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples
of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulphates,
expecially those obtained by sulphating higher (C
8-C
18) alcohols produced for example from tallow or coconut oil; sodium and potassium alkyl
(C
9-C
20) benzene sulphonates, particularly sodium linear secondary alkyl (C
10-C
15) benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers
of-the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived
from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates,;
sodium and potassium salts of sulphuric acid esters of higher (C
8-C
18) fatty alcohol-alkylene oxide, particularly ethylene oxide, reaction products; the
reaction products of fatty acids such as coconut fatty acids esterified with isethionic
acid and neutralised with sodium hydroxide; sodium and potassium salts of fatty acid
amides of methyl taurine; alkane monosulphonates such as those derived by reacting
alpha-olefins (C
8-C
20) with sodium bisulphite and those derived from reacting paraffins with SO
2 and C1
2 and then hydrolysing with a base to product a random sulphonate; and olefin sulphonates,
with term is used to describe the material made by reacting olefins, particularly
C
10-C
20 alpha-olefins, with S0
3 and then neutralising and hydrolysing the reaction product. The preferred anionic
detergent compounds are sodium (C
11-C
15) alkyl benzene sulphonates and sodium (C
16-C
18) alkyl sulphates.
[0036] Suitable nonionic detergent compounds which may be used include in particular the
reaction products of compounds having a hydrophobic group and a reactive hydrogen
atom, for example aliphatic alcohols, acids, amides or alkyl phenols with alkylene
oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionic
detergent compounds are alkyl (C
6-C
22) phenols-ethylene oxide condensates, generally 5 to 25 E0, i.e. 5 to 25 units of
ethylene oxide per molecule, the condensation products of aliphatic (C
8-C
18) primary or secondary linear or branched alcohols with ethylene oxide, generally
6 to 30 E0, and products made by condensation of ethylene oxide with the reaction
products of propylene oxide and ethylenediamine. Other so-called nonionic detergent
compounds include long chain tertiary amine oxides, long chain tertiary phosphine
oxides and dialkyl sulphoxides.
[0037] Mixtures of detergent compounds, for example mixed anionic or mixed anionic compounds
may be used in the detergent compositions, particularly in the latter case to provide
controlled low sudsing properties. This is beneficial for compositions intended for
use in suds-intolerant automatic washing machines. We have also found that the use
of some nonionic detergent compounds in the compositions decreases the tendency of
insoluble phosphate salts to deposit on the washed fabrics. especially when used in
admixture with some soaps as described below.
[0038] Amounts of amphoteric or zwitterionic detergent compounds can also be used in theccompositions
of the invention but this is not normally desired due to their relatively high cost.
If any amphoteric or zwitterionic detergent compounds are used it is generally in
small amounts in compositions based on the much more commonly used synthetic anionic
and/or nonionic detergent compounds. For example, mixtures of amine oxides and ethox-ylated
nonionic detergent compounds can be used.
[0039] Soaps may also be present in the detergent compositions of the invention, but not
as the sole detergent compounds. The soaps are particularly useful at low levels in
binary and ternary mixtures, together with nonionic or mixed synthetic anionic and
nonionic detergent compounds, which have low sudsing properties. The soaps which are
used are the sodium, or less desirably potassium, salts of C
10-C
24 fatty acids. It is particularly preferred that the soaps should be based mainly on
the longer chain fatty acids within this range, that is with at least half of the
soaps having a carbon chain length of 16 or over. This is most conveniently accomplished
by using soaps from natural sources such as tallow, palm oil or rapeseed oil, which
can be hardened if desired, with lesser amounts of other shorter chain soaps, prepared
from nut oils such as coconut oil or palm kernel oil. The amount of such soaps can
be up to about 25% by weight, with lower
[0040] amounts of about 0.5% to about 5% being generally sufficient for lather control.
Amounts of soap between about 2% and about 20%, especially between about 5% and about
15%,can advantageously be used to give a beneficial effect on detergency and reduced
levels of incrustation.
[0041] Apart from the essential detergent active compounds and detergency builders, the
detergent compositions used in the process of the invention can contain any of the
conventional additives in the amounts in which such materials are normally employed
in fabric washing detergent compositions. Examples of these additives include lather
boosters such as alkanolamides, particularly the monoethanolamides derived from palm
kernel fatty acids and coconut fatty acids, lather depressants such as alkyl phosphates,
waxes and silicones, antiredeposition agents such as sodium carboxymethylcellulose
and polyvinyl pyrrolidone optionally copolymerised with vinyl acetate, oxygen-releasing
bleaching agents such as sodium perborate and sodium percarbonate, per-acid bleach
precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid
and alkali metal salts of dischloroisocyanuric acid, fabric softening agents, inorganic
salts such as sodium sulphate, sodium carbonate and magnesium silicate, and, usually
present in very minor amounts, fluorescent agents, perfumes, enzymes such as proteases
and amylases, germicides and colourants.
[0042] It is particularly beneficial to include in the detergent compositions an amount
of sodium perborate, preferably between about 10% and 40%, for example about 15% to
about 30%, by weight. It has been found that the bleaching action of sodium perborate
is boosted under ' highly alkaline conditions which also give optimum detergency and
building action from the orthophosphate. Thus, it becomes possible to achieve improved
bleaching properties by using the same levels of sodium perborate as normal; or decreased
levels of sodium perborate can be used to give equal bleaching properties to those
of conventional products with higher levels of perborate and sodium tripolyphosphate
as the sole detergency builder. The latter option can also be used to further decrease
the raw materials costs of the compositions, if a cheap filler is used in place of
part of the sodium perborate.
[0043] It is desirable to include one or more antideposition agents in the detergent compositions
of the invention, to decrease the tendency to form inorganic deposits on washed fabrics.
It appears that the effective antideposition agents are materials which stabilise
insoluble calcium orthophosphate particles and thereby inhibit their deposition onto
the fabrics. The most effective antideposition agents are anionic polyelectrolytes,
especially polymeric aliphatic carboxylates. The amount of any such antideposition
agent can be from about 0.01% to about 10% of the compositions, but is normally from
about 0.1% to about 5% by weight, preferably from about 0.2% to about 2% by weight
of the compositions.
[0044] Specific preferred antideposition agents are the alkali metal or ammonium, preferably
the sodium, salts or homo-and
'co-polymers of acrylic acid or substituted acrylic acids, such as sodium polyacrylate,
the sodium salt of copolymeth- acrylamide/acrylic acid and sodium poly-alpha-hydroxyacrylate,
salts of copolymers of maleic anhydride with ethylene, acrylic acids vinylmethylether
allyl acetate or styrene,especially 1:1 copolymers, and optionally with partial esterification
of the carboxyl groups. Such copolymers preferably have relatively low molecular weights,.eg
in the range of about 1,000 to 50,000. Other antideposition agents include the sodium
salts of polymaleic acid, polyitaconic acid and polyaspartic acid, phosphate esters
of ethoxylated aliphatic alcohols, polyethylene glycol phosphate esters, and certain
phosphonates such as sodium ethane-1-hydroxy-1,1-diphosphonate, sodium ethylenediamine
tetramethylene phosphonate, and sodium 2-phosphonobutane tricarboxylate. Mixtures
of organic phosphonic acids or substituted acrylic acids or their salts with protective
colloids such as gelatin may also be used. The most preferred antideposition agent
is sodium polyacrylate having a MW of about 10,000 to 50,000, for example about 20,000
to 30,000.
[0045] It is also possible to include in the detergent compositions of the invention minor
amounts, preferably not more than about 20% by weight, of other non-phosphate: detergency
builders or sequestrant builders. This is of particular benefit where it is desired
to increase detergency whilst using particularly low levels of the essential alkali
metal tripolyphosphate and alkali metal orthophosphate builders, so as to achieve
especially low phosphorus contents in the detergent compositions. Examples of such
other detergency builders are amine carboxylates such as sodium nitrilotriacetate,
sodium carbonate, sodium amorphous or ahuminosilicate ion-exchange materials, sodium
citrate and soap, which can function as a detergency builder, as discussed above.
However, such other builder materials are not essential and it is a particular benefit
of using the mixed alkali metal tripolyphosphate and orthophosphate that satisfactory
detergency properties can be achieved at lower total phosphate levels than hitherto
considered necessary without other detergency builders.
[0046] It is generally also desirable to include in the compositions an amount of an alkali
metal silicate, particularly sodium ortho-, meta- or preferably neutral or alkaline
silicate. The presence of such alkali metal silicates at levels of at least about
1%, and preferably from about 5% to about 15%, by weight of the composition, is advantageous
in decreasing the corrosion of metal parts in washing machines, besides giving processing
benefits and generally improved powder properties. The more highly alkaline ortho-
and meta-silicates would normally only be used at lower amounts within this range,
in admixture with the neutral or alkaline silicates.
[0047] The compositions of the invention are required to be alkaline, but not too strongly
alkaline as this could result in fabric damage and also be hazardous for domestic
usage. In practice the compositions should normally give a pH of from 9 to 11 in use
in aqueous wash solution. It is preferred in particular for domestic products to have
a minimum pH of at least 9.25 and especially a pH of 9.5 or over, as lower pHs tend
to be less effective for optimum detergency building, and a maximum pH of 10.5, as
more highly alkaline products can be hazardous if misused. The pH is measured at the
lowest normal usage concentration of 0.1% w/v of the product in water of 12
0H (Ca), (French permanent hardness, calcium only) at 50°C so that a satisfactory degree
of alkalinity can be assured in use at all normal product concentrations.
[0048] The pH of the detergent compositions in use is controlled by the amount of orthophosphate
and any other alkaline salts such as alkali metal silicate, sodium perborate and sodium
carbonate present. The presence of such other alkaline salts, especially the alkali
metal silicates, is particularly beneficial, because the alkalinity of the alkali
metal orthophosphate is diminished in hard water due to precipitation of the calcium
salt. In addition the alkali metal tripolyphosphate is more stable and resistant to
hydrolysis under moderately alkaline conditions. The other ingredients in the alkaline
detergent compositions of the invention should of course be chosen for alkaline stability,
especially the pH sensitive materials such as enzymes.
[0049] The detergent compositions of the invention are preferably made in particulate form,
by admixture of a spray dried base powder and treated tripolyphosphate. However, if
desired, the detergent compositions may be compressed or compacted into tablets or
blocks, or otherwise treated for example by granulation, prior to packaging and sale.
Tocprotect the compositions during storage it may be desirable to use moisture impermeable
packaging for example in plastic or fabric sachets containing premeasured doses of
the detergent compositions for washing machine usage.
[0050] The invention is illustrated by the following Examples in which parts and percentages
are by weight except where otherwise indicated.
EXAMPLE 1
[0051] Detergency tests were accomplished to determine the effect of delayed addition of
sodium tripolyphosphate, using a nominal formulation of:
added with the other ingredients or after a specified delay.
[0052] Terg-o-tometer tests were undertaken, using a 25 minute wash cycle with a product
concentration of 10g/1 in water at 95°C and 22
0 German hardness. The level of inorganic depositions (ash) wasmeasuredfor the cotton
test cloths after 6 and 18 repeat wash cycles, using delays of 0,5,10 and 15 minutes
after the other ingredients before addition of the sodium tripolyphosphate,with the
following results:
[0053] These results show a marked reduction in the inorganic deposition caused by the delayed
tripolyphosphate addition. Further detergency tests showed that there was no significant
difference in detergency caused by the delay, when using a variety of different standard
test cloths.
[0054] The tests were repeated on a larger scale in a Miele automatic washing machine using
a product dosage of 200g in water of 22° German hardness, and the boilwash cycle in
which heating takes 30 minutes and the boil continues for 20 minutes. The sodium tripolyphosphate
was added after 0,15,30 or 40 minutes, with the following results on the inorganic
depositions, which confirm the benefit of delayed addition.
Detergency tests on varied test cloths in the same washes again showed slightly improved
wash results for the delayed addition of the sodium tripolyphosphate, but within the
margin of experimental error.
EXAMPLE 2
[0055] Experiments were carried out in a Tergotometer to demonstrate the effect of tripolyphosphate
on fabric incrustation . A detergent composition having the following formulation
was made up by mixing solutions.
[0056] Fabrics were washed using this composition to which orthophosphate, tripolyphosphate
and polyacrylate were added as set out below. The wash conditions were 40°FH wash
water hardness (Ca:Mg 4:1), 30°FH flood and hand rinse water hardness (Ca:Mg 4:1),
wash temperature 90°C, wash time 20 minutes, flood 2 minutes, rinse 5 minutes and
product dosage 14 g per litre.
[0057] The results achieved are set out in the following table. a
1. A process for washing fabrics characterised by comprising steps of:
( i) contacting the fabrics with a wash liquor containing a synthetic detergent active
compound and an alkalimetal or ammonium orthophosphate; and
(ii) subsequently contacting the fabrics with a wash liquor containing a synthetic
detergent active compound and an alkalimetal or ammonium tripolyphosphate, each of
said wash liquors having a pH between about 8 and about 12 and each of said wash liquors
containing substantially no alkalimetal pyrophosphate.
2. A process according to Claim 1, characterised by being carried out in two stages,
the fabrics being substantially separated from the wash liquor used in step (i) before
being contacted with the wash liquor used in step (ii).
3. A process according to Claim 1, characterised in that the wash liquor used in step
(i) remains in contact with the. fabrics during step (ii).
4. A process according to Claim 1, characterised in that step (ii) is carried out
at least 15 seconds after step (i).
5. A process according to Claim 1, characterised in that said alkalimetal or ammonium
tripolyphosphate is present in the wash liquor used in step (i) in an undissolved
form.
6. A detergent composition for washing fabrics by a method according to Claim 1, comprising
a synthetic detergent active compound, an alkalimetal or ammonium orthophosphate and
an alkalimetal or ammonium tripolyphosphate characterised by means for delaying the
solubility of said alkalimetal or ammonium tripolyphosphate when the composition is
added to water to form a wash liquor, said composition yielding a pH of between about
9 and about 11 when dissolved in 120H (Ca) water at 50°C and at a concentration of 0.1% w/v and said composition containing
substantially no alkalimetal pyrophosphate.
7. A detergent composition according to Claim 6, characterised by a first container
containing at least a part of said synthetic detergent active compound and said orthophosphate
and a second container containing said alkalimetal or ammonium tripolyphosphate and
optionally a further part of said synthetic detergent active compound.
8. A detergent composition according to Claim 7, characterised in that said first
container and said second container are constituted respectively by a first compartment
and a second compartment.of a sachet, said sachet being so constituted that when added
to water the contents of said first compartment are released before the contents of
said second compartment.
9. A detergent composition according to Claim 6, characterised in that said means
for delaying the solubility of said alkalimetal or ammonium tripolyphosphate is constituted
by a slowly dissolving material with which said tripolyphosphate is granulated or
encapsulated.
10. A detergent composition according to Claim 6, characterised by containing by weight:
from about 2.5% to about 50% of one or more synthetic detergent active compounds selected
from anionic, nonionic, amphoteric and zwitterionic synthetic detergent compounds;
from about 2% to about 20% of said alkalimetal or ammonium orthophosphate;
from about 2% to about 20% of said alkalimetal or ammonium tripolyphosphate in such
a form as to delay,
its solubility when the composition is added to water
to form a wash liquor, the ratio by weight of said orthophosphate to said tripolyphosphate
being from
about 3:1 to about 1:3;
optionally not more than about 20% non-phosphate detergency builders or sequesterant
builders;
optionally not more than about 25% soap; and
optionally one or more ingredients selected from lather boosters, antiredeposition
agents, oxygen-releasing agents, per-acid bleach precursors, chlorine-releasing bleaching
agents, fabric softening agents, inorganic salts, fluorescent agents, perfumes, enzymes,
germicides and colourants.