[0001] The present invention relates to detergent compositions comprising percarbonate bleach
particles. In particular it relates to compositions which have a high bulk density,
improved characteristics of dispensing from either the drawer of a washing machine,
or other dispensing device, thereby giving improved cleaning performance of bleaching
compositions.
[0002] Perborate bleach has been commonly used in detergent compositions. However it has
a tendency to promote gelling in the presence of surfactants and water which may prevent
the detergent composition from being rapidly and effectively dispersed in the wash
solution.
[0003] Percarbonate bleach is currently being proposed as an alternative to perborate bleach
which has commonly been used in detergent compositions in the past. Sodium percarbonate
is an attractive perhydrate for use in detergent compositions because it dissolves
readily in water, is weight efficient and, after giving up its available oxygen, provides
a useful source of carbonate ions for detergency purposes.
[0004] Particulate detergent components comprising surfactants and percarbonate have been
proposed in the prior art.
[0005] WO92/6163, published on 16th April, 1992, discloses granular compositions which comprise
percarbonate and surfactant particles. It states that a substantial amount of the
surfactant particles should have a particle size lying between 250 micrometers and
700 micrometers.
[0006] The application, which is mainly concerned with percarbonate stability, also mentions
the possibility of coating percarbonate with protective layer comprising carbonate
and sulphate.
[0007] EP510746, published on 28th October, 1992 describes surfactant agglomerates having
an average particle size of from 200 to 1000 micrometers. "Bleaching agents" and "perborate"
are specifically disclosed as optional components, but percarbonate is not mentioned.
[0008] A disadvantage which may be associated with high density surfactant agglomerates
is that they have slower rates of surfactant dissolution when compared to low density
products. This can reduce the overall cleaning performance because a slow rate of
surfactant dissolution causes a slow rate of fabric/soil wetting and a slow rate of
control of fabric softener cationic active residues on fabrics.
[0009] A proposed solution is to use more rapidly water soluble surfactants having a low
Krafft point, and fine surfactant agglomerate particle size in order to give more
rapid rates of surfactant dissolution.
However the combination of perborate monohydrate and fine particles of water soluble
anionic surfactant cause unacceptable level of drawer dispenser or granulette dosing
device residues. Any reduction of perborate monohydrate level reduces the performance
at low temperature.
[0010] It has now been found that the use of certain alkalimetal percarbonate materials
with fine particles of water soluble surfactant particles with high density show a
good dispensing profile and fast rates of surfactant and bleach dissolution.
Summary of the Invention
[0011] A granular detergent composition having a bulk density of at least 650 g/l, comprising:
i) granular surfactant agglomerates which comprise from 25% to 60% by weight of anionic
surfactant and which have a average particle size of less than 480 micrometers; and
ii) from 2% to 50% by weight of granular alkalimetal percarbonate.
Detailed Description of the Invention
[0012] A granular detergent composition having a bulk density of at least 650 g/l, comprising
a granular surfactant agglomerates which comprise from 25% to 60% by weight of anionic
surfactant, and from 2% to 50% by weight of granular alkalimetal percarbonate.
[0013] The average agglomerate particle size is less than 480 micrometers, preferably less
than 400 micrometers, and more preferably less than 350 micrometers.
[0014] At least 50% by weight of the anionic surfactant which is present in the agglomerates
is chosen from those anionic surfactants having a Krafft point of less than 38°C.
[0015] Preferred anionic surfactants are chosen from the group consisting of linear alkyl
benzene sulphonate with average chain length below C
12.2, alkyl sulphate having an alkyl chain which is predominantly C₁₁₋₁₅, preferably C₁₂₋₁₅
(branched), more preferably C₁₂₋₁₄ ( linear), alkyl ether sulphate or mixtures of
these. Most preferably alkyl sulphate and/or alkyl ether sulphate are used and linear
alkyl benzene sulphonate is excluded.
[0016] Preferred nonionic surfactants for use in the surfactant agglomerates include polyhydroxy
fatty acid amides, alkyl poly glucosides, alkyl polyglycerol ether, ethoxylated nonionic
surfactant, hydrophobic diols such as dodecane diols, and mixtures thereof.
[0017] The granular percarbonate of the present invention may be advantageously coated with
a soluble salt. Preferably a coating which comprises sodium carbonate, sodium sulphate,
citrate or mixtures of these is used.
[0018] Preferred levels of percarbonate are from 8% to 30% by weight, whereas perborate
should be present at a level of less than 3% by weight, and preferably perborate should
be excluded from the compositions of the present invention.
High Active Surfactant Containing Particles
[0019] A wide range of surfactants can be used in the detergent compositions. A typical
listing of anionic, nonionic, ampholytic and zwitterionic classes, and species of
these surfactants, is given in U.S.P. 3,929,678 issued to Laughlin and Heuring on
December, 30, 1975. A list of suitable cationic surfactants is given in U.S.P. 4,259,217
issued to Murphy on March 31, 1981.
[0020] The most suitable anionic surfactants for use in the present invention are those
having a Krafft point of less than 38°C. This can be measured by mixing 1g of an anionic
surfactant into 100 mls of distilled water and cooling the mixture in an ice bath,
allowing it to become cloudy. The solution is then slowly heated and the temperature
at which it becomes transparent is recorded. This temperature is the Krafft point.
[0021] Mixtures of low Krafft point (i.e. less than 38°C) anionic surfactant and high Krafft
point (i.e. more than 38°C) may be used in the present invention, although it is preferred
that the low Krafft point anionics represent at least 50% by weight of the total anionic
surfactant present in the surfactant particle.
[0022] Mixtures of anionic surfactants are suitable herein, particularly blends of sulphate,
sulphonate and/or carboxylate surfactants. Mixtures of sulphonate and sulphate surfactants
are normally employed in a sulphonate to sulphate weight ratio of from 5:1 to 1:2,
preferably from 3:1 to 2:3, more preferably from 3:1 to 1:1. Preferred sulphonates
include alkyl benzene sulphonates having from 9 to 15, most preferably less than 12
carbon atoms in the alkyl radical, and alpha-sulphonated methyl fatty acid esters
in which the fatty acid is derived from a C₁₀-C₁₈ fatty source, preferably from a
C₁₀-C₁₄ fatty source. In each instance the cation is an alkali metal, preferably sodium.
Preferred sulphate surfactants in such sulphonate sulphate mixtures are alkyl sulphates
having from 12 to 22, preferably 10 to 14 carbon atoms in the alkyl radical. Another
useful surfactant system comprises a mixture of two alkyl sulphate materials whose
respective mean chain lengths differ from each other. One examples of typical anionic
surfactant systems includes a mixture of C₁₂-C₁₄ alkyl sulphate and C₁₆-C₁₈ alkyl
sulphate in a weight ratio of C₁₂-C₁₄: C₁₆-C₁₈ of from 2:1. Another example is a mixture
of C₁₂-C₁₅ alkyl sulphate and C₁₄-C₁₅ alkyl sulphate in a weight ratio of C₁₂-C₁₅:
C₁₄-C₁₅ of from 1.5:1. The alkyl sulphates may also be combined with alkyl ethoxy
sulphates having from 10 to 20, preferably 10 to 14 carbon atoms in the alkyl radical
and an average degree of ethoxylation of 1 to 6. The cation in each instance is again
an alkali metal, preferably sodium.
[0023] Other anionic surfactants suitable for the purposes of the invention are the alkali
metal sarcosinates of formula
R-CON (R) CH₂ COOM
wherein R is a C₉-C₁₇ linear or branched alkyl or alkenyl group, R' is a C₁-C₄ alkyl
group and M is an alkali metal ion. Preferred examples are the lauroyl, Cocoyl (C₁₂-C₁₄),
myristyl and oleyl methyl sarcosinates in the form of their sodium salts.
[0024] Also useful are the sulphonation products of fatty acid methyl esters containing
a alkyl group with from 10 to 20 carbon atoms. Preferred are the C10-14 methyl ester
sulphonates (MES).
[0025] Whilst not being the main component of the anionic surfactant of the present invention
water-soluble salts of the higher fatty acids, i.e., "soaps", can be used in the compositions
herein. This includes alkali metal soaps such as the sodium, potassium, ammonium,
and alkylammonium salts of higher fatty acids containing from about 8 to about 24
carbon atoms, and preferably from about 12 to about 18 carbon atoms. Soaps can be
made by direct saponification of fats and oils or by the neutralization of free fatty
acids. Particularly useful are the sodium and potassium salts of the mixtures of fatty
acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut
soap.
[0026] The particles of the present invention will contain from 25% by weight to 60% by
weight, preferably 35% by weight to 55% by weight of anionic surfactant. The finished
compositions of the present invention will contain from 2% to 30% by weight, preferably
5% to 25% by weight of anionic surfactant.
[0027] One class of nonionic surfactants useful in the present invention comprises condensates
of ethylene oxide with a hydrophobic moiety, providing surfactants having an average
hydrophilic-lipophilic balance (HLB) in the range from 8 to 17, preferably from 9.5
to 13.5, more preferably from 10 to 12.5. The hydrophobic (lipophilic) moiety may
be aliphatic or aromatic in nature and the length of the polyoxyethylene group which
is condensed with any particular hydrophobic group can be readily adjusted to yield
a water-soluble compound having the desired degree of balance between hydrophilic
and hydrophobic elements.
[0028] Especially preferred nonionic surfactants of this type are the C₉-C₁₅ primary alcohol
ethoxylates containing 3-9 moles of ethylene oxide per mole of alcohol, particularly
the C₁₃-C₁₅ primary alcohols containing 6-9 moles of ethylene oxide per mole of alcohol
and the C₁₁-C₁₅ primary alcohols containing 3-5 moles of ethylene oxide per mole of
alcohol.
[0029] Another class of nonionic surfactants comprises alkyl polyglucoside compounds of
general formula
RO (C
nH
2nO)
tZ
x
wherein Z is a moiety derived from glucose; R is a saturated hydrophobic alkyl group
that contains from 12 to 18 carbon atoms; t is from 0 to 10 and n is 2 or 3; x is
from 1.3 to 4, the compounds including less than 10% unreacted fatty alcohol and less
than 50% short chain alkyl polyglucosides. Compounds of this type and their use in
detergent compositions are disclosed in EP-B 0070074, 0070077, 0075996 and 0094118.
[0030] Still another class of nonionic surfactants comprises alkyl poly glycerol ethers
which may be represented by the formula R - (O - CH2 - CHOH - CH2)n - OH, where R
is a C8-18 alkyl group and n is from 0 to 6.
[0031] Still another class of nonionic surfactants comprises polyhydroxy fatty acid amides
which may be produced by reacting a fatty acid ester and an N-alkyl polyhydroxy amine.
The preferred amine for use in the present invention is N-(R1)-CH2(CH2OH)4-CH2-OH
and the preferred ester is a C12-C20 fatty acid methyl ester. Most preferred is the
reaction product of N-methyl glucamine with C12-C20 fatty acid methyl ester.
[0032] Methods of manufacturing polyhydroxy fatty acid amides have been described in WO
92 6073, published on 16th April, 1992. This application describes the preparation
of polyhydroxy fatty acid amides in the presence of solvents. In a highly preferred
embodiment of the invention N-methyl glucamine is reacted with a C12-C20 methyl ester.
It also says that the formulator of granular detergent compositions may find it convenient
to run the amidation reaction in the presence of solvents which comprise alkoxylated,
especially ethoxylated (EO 3-8) C12-C15 alcohols.
[0033] A further class of surfactants are the semi-polar surfactants such as amine oxides.
Suitable amine oxides are selected from mono C₈-C₂₀, preferably C₁₀-C₁₄ N-alkyl or
alkenyl amine oxides and propylene-1,3-diamine dioxides wherein the remaining N positions
are substituted by methyl, hydroxyethyl or hydroxpropyl groups.
[0034] Cationic surfactants can also be used in the detergent compositions herein and suitable
quaternary ammonium surfactants are selected from mono C₈-C₁₆, preferably C₁₀-C₁₄
N-alkyl or alkenyl ammonium surfactants wherein remaining N positions are substituted
by methyl, hydroxyethyl or hydroxypropyl groups.
[0035] The surfactant containing particles will further comprise components selected from
a wide range of possible ingredients which are commonly used in laundry detergents.
Preferably the particles will contain some detergent builder:
These can include, but are not restricted to alkali metal carbonates, bicarbonates,
silicates, aluminosilicates, monomeric polycarboxylates, homo or copolymeric polycarboxylic
acids or their salts in which the polycarboxylic acid comprises at least two carboxylic
radicals separated from each other by not more than two carbon atoms, organic phosphonates
and aminoalkylene poly (alkylene phosphonates) and mixtures of any of the foregoing.
The builder system is present in an amount of from 25% to 60% by weight of the composition,
more preferably from 30% to 60% by weight.
[0036] Preferred builder systems are free of boron compounds and any polymeric organic materials
are preferably biodegradable.
[0037] Suitable silicates are those having an SiO₂:Na₂O ratio in the range from 1.6 to 3.4,
the so-called amorphous silicates of SiO₂ : Na₂O ratios from 2.0 to 2.8 being preferred.
These materials can be added at various points of the manufacturing process, such
as in the form of an aqueous solution serving as an agglomerating agent for other
solid components, or, where the silicates are themselves in particulate form, as solids
to the other particulate components of the composition.
[0038] Within the silicate class, highly preferred materials are crystalline layered sodium
silicates of general formula
NaMSi
xO
2x+1.yH₂O
wherein M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from
0 to 20. Crystalline layered sodium silicates of this type are disclosed in EP-A-0164514
and methods for their preparation are disclosed in DE-A-3417649 and DE-A-3742043.
For the purposes of the present invention, x in the general formula above has a value
of 2, 3 or 4 and is preferably 2. More preferably M is sodium and y is 0 and preferred
examples of this formula comprise the α,β,γ and δ forms of Na₂Si₂O₅. These materials
are available from Hoechst AG FRG as respectively NaSKS-11 and NaSKS-6. The most preferred
material is δ -Na₂Si₂O₅, (NaSKS-6). Crystalline layered silicates are incorporated
either as dry mixed solids, or as solid components of agglomerates with other components.
[0039] Whilst a range of aluminosilicate ion exchange materials can be used, preferred sodium
aluminosilicate zeolites have the unit cell formula
Na
z [(AlO₂ )
z (SiO₂ )
y ] xH ₂O
wherein z and y are at least 6; the molar ratio of z to y is from 1.0 to 0.5 and x
is at least 5, preferably from 7.5 to 276, more preferably from 10 to 264. The aluminosilicate
materials are in hydrated form and are preferably crystalline, containing from 10%
to 28%, more preferably from 18% to 22% water in bound form.
[0040] The above aluminosilicate ion exchange materials are further characterised by a particle
size diameter of from 0.1 to 10 micrometers, preferably from 0.2 to 4 micrometers.
The term "particle size diameter" herein represents the average particle size diameter
of a given ion exchange material as determined by conventional analytical techniques
such as, for example, microscopic determination utilizing a scanning electron microscope
or by means of a laser granulometer. The aluminosilicate ion exchange materials are
further characterised by their calcium ion exchange capacity, which is at least 200
mg equivalent of CaCO₃ water hardness/g of aluminosilicate, calculated on an anhydrous
basis, and which generally is in the range of from 300 mg eq./g to 352 mg eq./g. The
aluminosilicate ion exchange materials herein are still further characterised by their
calcium ion exchange rate which is at least 130 mg equivalent of CaCO₃/litre/minute/(g/litre)
[2 grains Ca⁺⁺/gallon/minute/gram/gallon)] of aluminosilicate (anhydrous basis), and
which generally lies within the range of from 130 mg equivalent of CaCo₃/litre/minute/(gram/litre)
[2 grains/gallon/minute/ (gram/gallon)] to 390 mg equivalent of CaCO₃/litre/minute/
(gram/litre) [6 grains/gallon/minute/(gram/gallon)], based on calcium ion hardness.
Optimum aluminosilicates for builder purposes exhibit a calcium ion exchange rate
of at least 260 mg equivalent of CaCO₃/litre/ minute/ (gram/litre) [4 grains/gallon/minute/
(gram/gallon)].
[0041] Aluminosilicate ion exchange materials useful in the practice of this invention are
commercially available and can be naturally occurring materials, but are preferably
synthetically derived. A method for producing aluminosilicate ion exchange materials
is discussed in US Patent No. 3,985,669. Preferred synthetic crystalline aluminosilicate
ion exchange materials useful herein are available under the designations Zeolite
A, Zeolite B, Zeolite X, Zeolite HS, Zeolite MAP and mixtures thereof. In an especially
preferred embodiment, the crystalline aluminosilicate ion exchange material is Zeolite
A and has the formula
Na ₁₂ [(AlO₂ ) ₁₂ (SiO₂)₁₂ ]. xH₂ O
wherein x is from 20 to 30, especially 27. Zeolite X of formula Na₈₆ [(A1O₂)₈₆(SiO₂)₁₀₆).
276 H₂O is also suitable, as well as Zeolite HS of formula Na₆ [(A1O₂)₆(SiO₂)₆] 7.5
H₂ O).
[0042] Suitable water-soluble monomeric or oligomeric carboxylate builders include lactic
acid, glycolic acid and ether derivatives thereof as disclosed in Belgian Patent Nos.
831,368, 821,369 and 821,370. Polycarboxylates containing two carboxy groups include
the water-soluble salts of succinic acid, malonic acid, (ethylenedioxy) diacetic acid,
maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric acid, as well
as the ether carboxylates described in German Offenlegenschrift 2,446,686, and 2,446,687
and U.S. Patent No. 3,935,257 and the sulfinyl carboxylates described in Belgian Patent
No. 840,623. Polycarboxylates containing three carboxy groups include, in particular,
water-soluble citrates, aconitrates and citraconates as well as succinate derivatives
such as the carboxymethyloxysuccinates described in British Patent No. 1,379,24l,
lactoxysuccinates described in British Patent No. 1,389,732, and aminosuccinates described
in Netherlands Application 7205873, and the oxypolycarboxylate materials such as 2-oxa-1,1,3-propane
tricarboxylates described in British Patent No. 1,387,447.
[0043] Polycarboxylates containing four carboxy groups include oxydisuccinates disclosed
in British Patent No. 1,261,829, 1,1,2,2-ethane tetracarboxylates, 1,1,3,3-propane
tetracarboxylates and 1,1,2,3-propane tetracarboxylates. Polycarboxylates containing
sulfo substituents include the sulfosuccinate derivatives disclosed in British Patent
Nos. 1,398,421 and 1,398,422 and in U.S. Patent No. 3,936,448, and the sulfonated
pyrolysed citrates described in British Patent No. 1,439,000.
[0044] Another preferred polycarboxylate builder is ethylenediamine-N,N'-disuccinic acid
(EDDS) or the alkali metal, alkaline earth metal, ammonium, or substituted ammonium
salts thereof, or mixtures thereof.
[0045] Alicyclic and heterocyclic polycarboxylates include cyclopentane-cis,cis,cis-tetracarboxylates,
cyclopentadienide pentacarboxylates, 2,3,4,5-tetrahydrofuran - cis, cis, cis-tetracarboxylates,
2,5-tetrahydrofuran - cis - dicarboxylates, 2,2,5,5-tetrahydrofuran - tetracarboxylates,
1,2,3,4,5,6-hexane - hexacarboxylates and carboxymethyl derivatives of polyhydric
alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include
mellitic acid, pyromellitic acid and the phthalic acid derivatives disclosed in British
Patent No. 1,425,343.
Of the above, the preferred polycarboxylates are hydroxycarboxylates containing up
to three carboxy groups per molecule, more particularly citrates.
[0046] The parent acids of the monomeric or oligomeric polycarboxylate chelating agents
or mixtures thereof with their salts, e.g. citric acid or citrate/citric acid mixtures
are also contemplated as components of builder systems of detergent compositions in
accordance with the present invention.
[0047] Other suitable water soluble organic salts are the homo- or co-polymeric polycarboxylic
acids or their salts in which the polycarboxylic acid comprises at least two carboxyl
radicals separated from each other by not more than two carbon atoms. Polymers of
the latter type are disclosed in GB-A-1,596,756. Examples of such salts are polyacrylates
of MWt 2000-5000 and their copolymers with maleic anhydride, such copolymers having
a molecular weight of from 20,000 to 70,000, especially about 40,000. Such builder
polymeric materials may be identical to the polymeric materials as binder materials
and coating materials, as described hereinabove. These materials are normally used
at levels of from 0.5% to 10% by weight more preferably from 0.75% to 8%, most preferably
from 1% to 6% by weight of the composition.
[0048] Organic phosphonates and amino alkylene poly (alkylene phosphonates) include alkali
metal ethane 1-hydroxy diphosphonates, nitrilo trimethylene phosphonates, ethylene
diamine tetra methylene phosphonates and diethylene triamine penta methylene phosphonates,
although these materials are less preferred where the minimisation of phosphorus compounds
in the compositions is desired.
[0049] Examples of other components which may be used in laundry detergents, and which may
be incorporated into the surfactant particles are described below under "Optional
Ingredients"
Percarbonate bleach
[0050] The compositions of the present invention will include a percarbonate bleach, normally
in the form of the sodium salt, as the source of alkaline hydrogen peroxide in the
wash liquor. This percarbonate is normally incorporated at a level of from 2% to 50%
by weight, more preferably from 5% to 30% by weight and most preferably from 8% to
25% by weight of the total composition.
[0051] Sodium percarbonate is an addition compound having a formula corresponding to 2Na₂CO₃.3H₂O₂,
and is available commercially as a crystalline solid. Most commercially available
material includes a low level of a heavy metal sequestrant such as EDTA, 1-hydroxyethylidene
1, 1-diphosphonic acid (HEDP) or an amino-phosphonate, that is incorporated during
the manufacturing process. For the purposes of the detergent composition aspect of
the present invention, the percarbonate can be incorporated into detergent compositions
without additional protection, but preferred executions of such compositions utilise
a coated form of the material. The preferred coating is a mixed salt of an alkali
metal sulphate and carbonate. Such coatings together with coating processes have previously
been described in GB-1,466,799, granted to Interox on 9th March 1977. The weight ratio
of the mixed salt coating material to percarbonate lies in the range from 1:200 to
1:4, more preferably from 1:99 to 1:9, and most preferably from 1:49 to 1:19. Preferably,
the mixed salt is of sodium sulphate and sodium carbonate which has the general formula
Na₂SO₄.n.Na₂CO₃ wherein n is from 0.1 to 3, preferably n is from 0.3 to 1.0 and most
preferably n is from 0.2 to 0.5. Another preferred coating material is citrate, or
mixtures of citrate with sulphate or carbonate. Water soluble surfactants may also
be used as coating materials.
[0052] An alternative, although less preferred coating material is sodium silicate of SiO₂:Na₂O
ratio from 1.6:1 to 3.4:1, preferably 2.8:1, applied as an aqueous solution to give
a level of from 2% to 10%, (normally from 3% to 5%) of silicate solids by weight of
the percarbonate. Magnesium silicate can also be included in the coating. However
silicate should not be the major coating agent in order to maintain good dispensing
properties. If present, the silicate level in the coating should be less than 3% by
weight of the percarbonate.
[0053] The particle size range of the crystalline percarbonate is from 150 micrometers to
1500 micrometers, preferably from 250 micrometers to 1000 micrometers with a mean
particle size of from 500 micrometers to 700 micrometers.
[0054] Whilst heavy metals present in the sodium carbonate used to manufacture the percarbonate
can be controlled by the inclusion of sequestrants in the reaction mixture, the percarbonate
still requires protection from heavy metals present as impurities in other ingredients
of the product.
[0055] In order for the benefits of the present invention to be fully realised, it is highly
desirable that the percarbonate material chosen can be rapidly disolved in the wash
and the active bleaching species are readily formed. In order to choose suitable percarbonate
materials the available oxygen (AvO2) level can be measured using thiosulphate/ potassium
iodide/ ammonium molybdate titration on aliquots taken from a stirred aqueous solution
of the 1% wt./wt. concentration of the detergent composition which contains the percarbonate
after 2, 4 and 5 minutes. A sample of the composition is dissolved in a Sotax apparatus
in deionised water which has been adjusted to 25°dH water hardness by the addition
of calcium chloride and magnesium chloride (with Ca:Mg = 3:1), at 10°C. The solution
is stirred at 150 rpm. A given percarbonate is considered to be suitable for use in
the present invention if it releases at least 40% of the total AvO2 after 2 minutes,
at least 80% of the total AvO2 after 4 minutes, and at least 90% of the total AvO2
after 5 minutes.
[0056] Compositions of the present invention, which contain percarbonate, have a greatly
reduced tendency to form undesirable gels in the presence of surfactants and water
than similar compositions which contain perborate. Without wishing to be bound by
theory, it is believed that this is because the type of percarbonate which is selected
here has a lower surface area and lower porosity than perborate monohydrate.This low
surface area and low porosity prevents the co-gelling with fine particles of surfactant
agglomerates and is therefore not detrimental to dispensing.
Optional Ingredients
[0057] Detergent compositions of the present invention may, optionally, include anti-redeposition
and soil suspension agents, bleach activators, optical brighteners, soil release agents,
suds suppressors, enzymes, fabric softening agents, perfumes and colours, as well
as other ingredients known to be useful in laundry detergents.
[0058] Anti-redeposition and soil-suspension agents suitable herein include cellulose derivatives
such as methylcellulose, carboxymethylcellulose and hydroxyethycellulose, and homo-or
co-polymeric polycarboxylic acids or their salts. Polymers of this type include copolymers
of maleic anhydride with ethylene, methylvinyl ether or methacrylic acid, the maleic
anhydride constituting at least 20 mole percent of the copolymer. These materials
are normally used at levels of from 0.5% to 10% by weight, more preferably from 0.75%
to 8%, most preferably from 1% to 6% by weight of the composition.
[0059] Other useful polymeric materials are the polyethylene glycols, particularly those
of molecular weight 1000-10000, more particularly 2000 to 8000 and most preferably
about 4000. These are used at levels of from 0.20% to 5% more preferably from 0.25%
to 2.5% by weight. These polymers and the previously mentioned homo- or co-polymeric
polycarboxylate salts are valuable for improving whiteness maintenance, fabric ash
deposition, and cleaning performance on clay, proteinaceous and oxidizable soils in
the presence of transition metal impurities.
[0060] In a preferred embodiment of the present invention, the composition comprises peroxyacid
bleach precursor. The solid peroxyacid bleach precursors of the present invention
comprise precursors containing one or more N- or O- acyl groups, which precursors
can be selected from a wide range of classes.
[0061] Suitable classes include anhydrides, esters, imides and acylated derivatives of imidazoles
and oximes, and examples of useful materials within these classes are disclosed in
GB-A-1586789. The most preferred classes are esters such as are disclosed in GB-A-836988,
864,798, 1147871 and 2143231 and imides such as are disclosed in GB-A-855735 & 1246338.
[0062] Particularly preferred precursor compounds are the N-,N,N¹N¹ tetra acetylated compounds
of formula

wherein x can be 0 or an integer between 1 & 6.
[0063] Examples include tetra acetyl methylene diamine (TAMD) in which x=1, tetra acetyl
ethylene diamine (TAED) in which x=2 and tetraacetyl hexylene diamine (TAHD) in which
x=6. These and analogous compounds are described in GB-A-907356. The most preferred
peroxyacid bleach precursor is TAED.
[0064] Other activators are perbenzoic acid precursors such as benzoyloxybenzene sulphonate
(BOBS) and benzoyl caprolactam.
[0065] Is is most preferred that a peroxyacid bleach precursor is present at a level of
at least 0.5% by weight of the composition. The particles of peroxyacid bleach precursor
preferably have a particle size of from 100 micrometers to 1500 micrometers.
[0066] These peroxyacid bleach precursors can be partially replaced by preformed peracids
such as N,N phthaloylaminoperoxy acid (PAP), nonyl amide of peroxyadipic acid (NAPAA),
1,2 diperoxydodecanedioic acid (DPDA) and trimethyl ammonium propenyl imidoperoxy
mellitic acid (TAPIMA). Other bleach precursors include glycolate esters (described
in EP 507475); 4h-3,1 - benzoxazin - 4 ones; cationic precursors (described in EP
458396 and EP 464880); ester carbonate activators (described in EP 475511), NOBS,
iso-NOBS.
[0067] Preferred optical brighteners are anionic in character, examples of which are disodium
4,4¹-bis-(2-diethanolamino-4-anilino -s- triazin-6- ylamino)stilbene-2:2¹ disulphonate,
disodium 4,4¹-bis-(2-morpholino -4-anilino-2-triazin-6-ylaminostilbene-2:2¹-disulphonate,disodium
4, 4¹-bis-(2,4-dianilino-s-triazin-6-ylamino)stilbene-2:2¹ - disulphonate, monosodium
4¹
,4¹¹-bis-(2,4-dianilino-s-triazin-6 ylamino)stilbene-2- sulphonate, disodium 4,4¹-bis-(2-anilino-4-(N-methyl-N-2-hydroxyethylamino)-2-triazin-6-ylamino)stilbene-2,2¹
- disulphonate, disodium 4,4¹-bis-(4-phenyl-2,1,3-triazol-2-yl)stilbene-2,2¹ disulphonate,
disodium 4,4¹bis(2-anilino-4-(1-methyl-2-hydroxyethylamino)-s-triazin-6-ylamino)stilbene-2,2¹disulphonate
and sodium 2(stilbyl-4¹¹-(naphtho-1¹,2¹:4,5)-1,2,3 - triazole-2¹¹- sulphonate.
[0068] Soil-release agents useful in compositions of the present invention are conventionally
copolymers or terpolymers of terephthalic acid with ethylene glycol and/or propylene
glycol units in various arrangements. Examples of such polymers are disclosed in the
commonly assigned US Patent Nos. 4116885 and 4711730 and European Published Patent
Application No. 0272033. A particular preferred polymer in accordance with EP-A-0272033
has the formula
(CH₃(PEG)₄₃)
0.75(POH)
0.25(T-PO)
2.8(T-PEG)
0.4]T(PO- H)
0.25((PEG)₄₃CH₃)
0.75
where PEG is -(OC₂H₄)O-, PO is (OC₃H₆O) and T is (pCOC₆H₄CO).
[0069] Certain polymeric materials such as polyvinyl pyrrolidones typically of MWt 5000-20000,
preferably 10000-15000, also form useful agents in preventing the transfer of labile
dyestuffs between fabrics during the washing process.
[0070] Another optional detergent composition ingredient is a suds suppressor, exemplified
by silicones, and silicasilicone mixtures. Silicones can be generally represented
by alkylated polysiloxane materials while silica is normally used in finely divided
forms, exemplified by silica aerogels and xerogels and hydrophobic silicas of various
types. These materials can be incorporated as particulates in which the suds suppressor
is advantageously releasably incorporated in a water-soluble or water-dispersible,
substantially non-surface-active detergent-impermeable carrier. Alternatively the
suds suppressor can be dissolved or dispersed in a liquid carrier and applied by spraying
on to one or more of the other components.
[0071] As mentioned above, useful silicone suds controlling agents can comprise a mixture
of an alkylated siloxane, of the type referred to hereinbefore, and solid silica.
Such mixtures are prepared by affixing the silicone to the surface of the solid silica.
A preferred silicone suds controlling agent is represented by a hydrophobic silanated
(most preferably trimethyl-silanated) silica having a particle size in the range from
10 nanometers to 20 nanometers and a specific surface area above 50 m²/g, intimately
admixed with dimethyl silicone fluid having a molecular weight in the range from about
500 to about 200,000 at a weight ratio of silicone to silanated silica of from about
1:1 to about 1:2.
[0072] A preferred silicone suds controlling agent is disclosed in Bartollota et al. US
Patent 3,933,672. Other particularly useful suds suppressors are the self-emulsifying
silicone suds suppressors, described in German Patent Application DTOS 2,646,126 published
April 28, 1977. An example of such a compound is DC0544, commercially available from
Dow Corning, which is a siloxane/glycol copolymer.
[0073] The suds suppressors described above are normally employed at levels of from 0.001%
to 0.5% by weight of the composition, preferably from 0.01% to 0.1% by weight.
[0074] The preferred methods of incorporation comprise either application of the suds suppressors
in liquid form by spray-on to one or more of the major components of the composition
or alternatively the formation of the suds suppressors into separate particulates
that can then be mixed with the other solid components of the composition. The incorporation
of the suds modifiers as separate particulates also permits the inclusion therein
of other suds controlling materials such as C₂₀-C₂₄ fatty acids, microcrystalline
waxes and high MWt copolymers of ethylene oxide and propylene oxide which would otherwise
adversely affect the dispersibility of the matrix. Techniques for forming such suds
modifying particulates are disclosed in the previously mentioned Bartolotta et al
US Patent No. 3,933,672.
[0075] Another optional ingredient useful in the present invention is one or more enzymes.
[0076] Preferred enzymatic materials include the commercially available amylases, neutral
and alkaline proteases, lipases, esterases and cellulases conventionally incorporated
into detergent compositions. Suitable enzymes are discussed in US Patents 3,519,570
and 3,533,139.
[0077] Fabric softening agents can also be incorporated into detergent compositions in accordance
with the present invention. These agents may be inorganic or organic in type. Inorganic
softening agents are examplified by the smectite clays disclosed in GB-A-1,400,898.
Organic fabric softening agents include the water insoluble tertiary amines as disclosed
in GB-A-1514276 and EP-B-0011340.
[0078] Their combination with mono C₁₂-C₁₄ quaternary ammonium salts is disclosed in EP-B-0026527
& 528. Other useful organic fabric softening agents are the dilong chain amides as
disclosed in EP-B-0242919. Additional organic ingredients of fabric softening systems
include high molecular weight polyethylene oxide materials as disclosed in EP-A-0299575
and 0313146.
[0079] Levels of smectite clay are normally in the range from 5% to 15%, more preferably
from 8% to 12% by weight, with the material being added as a dry mixed component to
the remainder of the formulation. Organic fabric softening agents such as the water-insoluble
tertiary amines or dilong chain amide materials are incorporated at levels of from
0.5% to 5% by weight, normally from 1% to 3% by weight, whilst the high molecular
weight polyethylene oxide materials and the water soluble cationic materials are added
at levels of from 0.1% to 2%, normally from 0.15% to 1.5% by weight. Where a portion
of the composition is spray dried, these materials can be added to the aqueous slurry
fed to the spray drying tower, although in some instances it may be more convenient
to add them as a dry mixed particulate, or spray them as a molten liquid on to other
solid components of the composition.
Processing
[0080] The high active surfactant particles of the present invention may take the form of
flakes, prills, marumes, noodles, ribbons, but preferably take the form of granules.
In order to achieve the low gelling properties which are an essential feature of the
present invention, it has now been found that the most preferred way to process the
particles is by agglomerating powders (such as those described hereinabove e.g. aluminosilicate,
carbonate) with high active surfactant pastes and to control the particle size of
the resultant agglomerates within specified limits. Such a process involves mixing
an effective amount of powder with a high active surfactant paste in one or more agglomerators
such as a pan agglomerator, a Z-blade mixer or more preferably an in-line mixer such
as those manufactured by Schugi (Holland) BV, 29 Chroomstraat 8211 AS, Lelystad, Netherlands,
and Gebruder Lodige Maschinenbau GmbH, D-4790 Paderborn 1, Elsenerstrasse 7-9, Postfach
2050, Germany. Most preferably a high shear mixer is used such as a Lodige CB (Trade
Name).
A high active surfactant paste comprising from 50% by weight to 95% by weight, preferably
70% by weight to 85% by weight of surfactant is used. The surfactant sustem may comprise
any of the groups of anionic, nonionic, cationic, amphoteric, and zwitterionic surfactants,
or mixtures of these. The paste may be pumped into the agglomerator at a temperature
high enough to maintain a pumpable viscosity, but low enough to avoid degradation
of the anionic surfactants used. An operating temperature of the paste of 50°C to
80°C is typical.
A particularly suitable process of making surfactant particles from high active surfactant
pastes is more fully described in EP 510 746, published on 28th October, 1992.
[0081] The term mean particle size as defined herein is calculated by sieving a sample of
the composition into a number of fractions (typically 5 fractions) on a series of
Tyler sieves. The weight fractions thereby obtained are plotted against the aperture
size of the sieves. The mean particle size is taken to be the aperture size through
which 50% by weight of the sample would pass. For the purposes of the present invention
the surfactant containing granules should have a mean partle size of less than 480
micrometers, preferably less than 400 micrometers, and most preferably less than 350
micrometers.
[0082] According to the present invention, the free-flowing surfactant particles made by
the process described above are then mixed with other detergent components in order
to produce a finished detergent composition.
[0083] The surfactant particles are mixed with the particles containing the alkalimetal
percarbonate.
[0084] All of the ingredients of the final composition may be mixed or blended in any suitable
piece of equipment, such as a rotating drum. Liquid ingredients such as nonionic surfactant
and perfume may be sprayed on to the surface of one or more of the constituent granules,
or onto the finished composition.
[0085] Appropriate choice of consitituent particles is required in order to ensure that
the finished composition has a bulk density of at least 650 g/l, preferably 750-1100
g/l.
EXAMPLES
[0086] In these examples the following abbreviations have been used:
- DTPMP:
- Diethylene triamine penta (methylene phosphonic acid), supplied by Monsanto as Dequest
2060 (trade name).
- Sokolan CP5:
- Co-polymer of acrylic and maleic acid, supplied by BASF.
- C14/15AE7:
- Ethoxylated alcohol having C14 to C15 chain length and an average of 7 ethoxy groups
per molecule
- C16/18AE11:
- Ethoxylated alcohol having C16 to C18 chain length and an average of 11 ethoxy groups
per molecule
- LAS:
- linear alkyl benzene sulphonate
- C16/18AS:
- Alkyl sulphate having alkyl chain length of predominantly C16 to C18
- C12/15AS:
- Alkyl sulphate having alkyl chain length of predominantly C12 to C15
- C12/15AE3:
- Ethoxylated alcohol having C12 to C15 chain length and an average of 3 ethoxy groups
per molecule
- CMC:
- Carboxy methyl cellulose
- PB1:
- Sodium perborate, monohydrate
- PB4:
- Sodium perborate, tetrahydrate
- TAED:
- N,N,N,N-tetraacetylethylene diamine
- Percarbonate:
- Sodium percarbonate coated with 2.5% carbonate/sulphate.
- Silicate:
- Granular silicate with a mean particle size of 600 micrometers, supplied by Akzo.

[0087] The compositions of examples A to E were prepared by:
1) spray drying a slurry comprising components a) to c);
2) spraying components d) and e) on to the spray dried powder.
3) forming agglomerates in a Loedige (Trade Name) high speed mixer from components
f) to o); and
4) dry mixing the spray dried powder and the agglomerates together with components
p) to x)
Comparative example D was found to give poor dispensing, but a good rate of dissolution
due to the small particle size (mean=340 micrometers) of the surfactant containing
agglomerates.
Comparative example E shows good dispensing but a poor rate of dissolution due to
the larger particle size (mean= 600 micrometers).
Example A shows both good dispensing and a good rate of dissolution due to the small
agglomerate size (mean = 340 micrometers) and the presence of percarbonate as the
bleaching agent in the composition.
[0088] Compositions of examples A, D, and E were tested in realistic washing conditions
in a washing machine. A was found to outperform both D and E over a wide range of
stains, especially at low washing temperatures.