EP0652940B1

EP0652940B1 - Detergent compositions

Info

Publication number: EP0652940B1
Application number: EP93917976A
Authority: EP
Inventors: James 4 Orchard Road Swales
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1992-08-03
Filing date: 1993-08-03
Publication date: 1997-03-12
Anticipated expiration: 2013-08-03
Also published as: GB9216454D0; DE69308856T2; DE69308856D1; DK0652940T3; AU678378B2; ATE150082T1; EP0652940A1; WO1994003580A1; AU4720493A; NZ254900A; JPH07509520A; ZA935578B; CA2141452A1; ES2098767T3

Abstract

Non-aqueous liquid landry detergent compositions which contain a condensed phosphate builder e.g. sodium tripolyphosphate, are rendered more easily dispersed during use, particularly when dispensed using a dosing means, by including a small quantity of a water soluble salt of a hydroxycarboxylic, especially citric or tartaric, acid especially an ammonium, substituted ammonium or alkali metal salt. The compositions include a surfactant, desirably a non-ionic surfactant and may include a bleach e.g. sodium perborate or percarbonate. Desirably a polyoxyalkylene glycol, especially ethylene glycol, having a molecular weight of 100 to 1500 D is also included. The solids of the composition are preferably present as finely divided e.g. less thant 10 mu m average size, particles in the liquid components.

Description

This invention relates to detergent compositions and in particular to non-aqueous laundry liquid detergent compositions.
Detergent compositions are known which comprise a suspension of a builder and optionally other solids in an organic liquid which comprises a surfactant. Non-aqueous compositions of this type, of good stability, are described in European Patent Specifications Nos EP 0030096 B and EP 0120659 B. Such compositions may contain phosphate builders, for example alkali metal condensed phosphates, for example sodium tripolyphosphate.
When a non aqueous composition comprising a condensed phosphate builder is contacted with water it is possible with certain models of washing machine if used with certain washing programmes to form a solid deposit comprising the builder which is slow to dissolve. If access of water to the deposit is limited the deposit may not dissolve during the washing process.
In some cases detergents are placed in containers which are introduced into the washing zone. If the container has restricted access solid deposits may be left in it especially if it was not dry when detergent was placed in it.
We have now found that if a minor quantity of a water soluble salt of a hydroxycarboxylic acid, particularly of tartaric or citric acid, is included in the composition this problem with condensed phosphate builders can be substantially mitigated.
This invention accordingly provides a substantially non-aqueous liquid laundry detergent composition which comprises a surfactant, a condensed phosphate builder and a water soluble salt of a hydroxycarboxylic acid containing 1 to 6 -COOH groups and 1 to 5 -OH groups in an amount to give a weight ratio of the condensed phosphate builder to the hydroxy carboxylic acid of 60:1 to 5:1.
By "substantially non-aqueous" we mean that the amount of water in the composition is sufficiently small that the tendency of the condensed phosphate builder to hydrolyse and thus to cause the viscosity of the detergent formulation to increase or the formulation to gel during storage prior to use is overcome. In practice, it is free water i.e. water that is not chemically bound as in water of crystallisation, in the formulation that is problematical and the amount of free water will usually be kept to less than 2%, and very desirably less than 1%, by weight of the composition. Small quantities of free water are typically present in various components of the formulation e.g. non-ionic surfactants and polyethylene glycol, and it is the concentration of water from such sources that should be kept suitably low. Water of crystallisation in materials such as the hydroxycarboxylic acid salt(s), as in sodium citrate dihydrate, is not usually a problem.
The hydroxycarboxylic acid salt is desirably a salt of an acid which contains a total of at least 3 hydroxyl and carboxyl groups. Salts of tartaric and citric acids are particularly useful materials. Mixtures of salts of these acids can be used if desired. The use of salts of either or both of these acids forms a particularly advantageous feature of this invention. The salt cation is desirably an ammonium, substituted ammonium or alkali metal, particularly sodium, salt. The salt is present in an amount to give a weight ratio of the condensed phosphate builder to the hydroxycarboxylic acid salt of 60:1 to 5:1, particularly 30:1 to 7:1, especially about 20:1. The amount of hydroxycarboxylic acid salt used in compositions of this invention is relatively small. At relatively high concentrations, hydroxycarboxylic acid salts can act as builders in detergent formulations. In this invention, the amount used is typically sufficiently small that the hydroxycarboxylic acid salt does not provide significant effect as a builder over and above that provided by the condensed phosphate builder.
The composition is preferably alkaline in reaction i.e. when added to water, as in use, the laundry water is rendered alkaline. It is preferred that normally acidic substances when present in the composition are in a form neutralised with alkali, particularly containing one or more of ammonium, substituted ammonium or, and preferably, alkali metal ions. Specific additives can be included to control the alkalinity of the laundry water in use, such as sodium disilicate or, especially if somewhat less alkaline conditions are desired, sodium bicarbonate.
The condensed phosphate builder may be an alkali metal, preferably a potassium or sodium salt of a condensed phosphate. Linear condensed phosphates are better builders than cyclic materials and are thus preferred. Typically the condensed phosphate will be a di-phosphate (pyrophosphate) for example sodium pyrophosphate Na₄P₂O₇, or tri-phosphate (tripolyphosphate), for example potassium tripolyphosphate, or, and particularly desirably, sodium tripolyphosphate. The total builder content of the composition (including the condensed phosphate builder) will generally be from 25 to 60% by weight. Other builders e.g. sodium carbonate and sodium bicarbonate, can be included if desired, but the amounts of such builders, when present, are usually relatively small for example from 1 to 10% by weight of the composition.
The composition can include a bleach such as a perborate or percarbonate e.g. as an alkali metal, particularly sodium, salt. When used, the amount of the bleach will typically be from 1 to 25%, particularly 2 to 20%, more particularly 5 to 20%, and especially about 10 to about 15%, by weight of the composition. Further, a bleach activator such as tetra-acetyl ethylene diamine, can also be included in the composition.
The surfactant will typically include at least one non-ionic surfactant. Suitable non-ionic surfactants include alkylene oxide derivatives, particularly where the alkylene oxide is ethylene and/or propylene oxide, especially ethylene oxide. Particularly suitably materials include reaction products of an amine, alkyl phenol or alkanol with ethylene and/or propylene oxide, especially ethylene oxide. When amine reaction products are used, the amine will usually be an alkyl amine in which the alkyl group can be straight or branched chain and can contain from 6 to 20, particularly 10 to 16, carbon atoms. When alkyl phenol reaction products are used, the alkyl group can be straight or branched chain and can contain from 6 to 20, particularly 6 to 12, carbon atoms. When alkanol reaction products are used, the alkanol is preferably a primary or secondary alkanol having a linear or mono branched alkyl chain and the alkanol can contain 6 to 20, preferably 10 to 16, carbon atoms. Suitably the (poly)oxyalkylene chain in the non-ionic surfactant has from 1 to 10, preferably 3 to 8, alkylene oxide residues. Of course, the number of alkylene oxide residues given is an average value. The amount of non-ionic surfactant is typically from 5 to 25%, particularly 7 to 20%, by weight of the composition.
Although non-ionic surfactants are generally the preferred surfactants in this invention, the surfactant may alternatively be or include one or more anionic or cationic surfactants. Such anionic or cationic surfactants may be of known type for example the anionic detergents may be soaps, alkylbenzene or olefin sulphonates, alcohol sulphates or alcohol alkoxylate sulphates; the cationic surfactants are suitably di-C_10-22 and preferably di-C_16-18 alkyl, di-lower alkyl ammonium salts or hydroxides for example chlorides or sulphates or for example fabric softeners of the C_10-16 alkyl, di-lower alkyl (for example methyl), substituted ethyl ammonium salts. The substituent on the ethyl group may be an -OOCR group where R is a C_13-22 alkyl group, and the anion of the salt may be a RSO₄- group where R is lower alkyl for example methyl. The lower alkyl groups are suitably methyl groups.
The composition desirably also includes a polyalkylene glycol, for example a polyethylene/polypropylene glycol or and particularly advantageously a polyethylene glycol. This enhances the fluidity of the compositions and, particularly where the polyalkylene glycol is a polyethylene glycol, is readily biodegradable. The polyalkylene glycol, particularly a polyethylene glycol, desirably has a molecular weight of 100 to 1500 D, especially 100 to 500, and for example 150 to 400 D. Polyalkylene glycols, particularly polyethylene glycols, of average molecular weight 100 to 400 and preferably 150 to 300 are especially useful as they can act to reduce the pour point of the liquid laundry detergent compositions thus making them more easily usable in a cold environment. When present the polyalkylene glycol, particularly polyethylene glycol is typically present as 5 to 55%, particularly 10 to 50% and especially 25 to 45%, by weight of the composition.
The composition may also contain additives conventionally found in detergent compositions, for example fabric conditioners, anti-redeposition aids such as carboxymethyl cellulose (see below), pH adjusters (see above), anti-corrosion additives e.g. sodium disilicate (which also acts as a pH adjuster), optical brighteners, sequestrants e.g. ethylene diamine tetra-acetic acid, dyes, perfumes and/or enzymes.
The liquid composition will generally take the form of a dispersion of solid particles in a liquid medium.
Typically the solids will include the condensed phosphate builder, other inorganic builders, when present, the hydroxycarboxylic acid salt(s), the bleach, when present, and other solid minor components not soluble in the liquid medium. Usually, the laundry liquid composition will comprise 25 to 70Z and particularly 30 to 65%, for example 40 to 65%, by weight of total solids. Desirably, to reduce the tendency of the solid to separate from the liquid component, the solids will be finely divided solids and in particularly the solids have an average particle size of at most 10 µm and very particularly from 1.2 to 8 µm. To avoid the composition having a 'gritty' appearance or feel, the proportion of relatively large particles will usually be kept small and, thus, it is very desirable that at least 90% of the solid particles have a size of less than 10 µm. Stated particle sizes are the diameters of particles of equal volume. Desirably, he particle size distribution is relatively narrow so that average particle sizes expressed as number average or weight average sizes are similar. Particle sizes can be measured, for example, using Coulter counters or laser particle size measuring equipment such as that sold under the Malvern name.
Typically, the liquid medium will include the liquid surfactant such as non-ionic surfactant(s), when present, the polyoxyalkylene glycol, when present, other minor liquid components and solid components soluble in the liquid medium. Corresponding to the solids content of the laundry liquid composition, the liquid medium will comprise 75 to 30% and particularly 70 to 35%, for example 60 to 35%, by weight of the composition.
Cationic and anionic surfactants when present will, depending on their properties either form part of the solids or will be wholly or partly liquid or dissolved in the liquid medium.
The formulation can include anti-redeposition aids. These include polycarboxylic acids having at least 10, usually at least 100, particularly 150 to 2000 and especially 200 to 1000, COOH groups. Carboxymethyl cellulose is a suitable anti-redeposition aid.
The composition suitably has a pour point (ASTM D 97-66, 1971) of less than 10°C and particularly less than 5°C. The pour point may be adjusted by varying the liquid phase composition, for example, by including surfactants and/or polyethylene glycol of low pour point.
In compositions according to the invention the dispersion of the solids in the non-ionic surfactant is remarkably stable especially if the particle size of the solids is at most 10 µm. If the solids separate at all then the resulting phase is usually loosely flocculated and is readily redispersible while if the relative amounts of the solids, polyethylene glycol and surfactant in the composition are correctly chosen there is little phase separation as the liquid fills the space between the loosely packed solid particles.
An especially useful substantially non-aqueous liquid laundry detergent composition which forms a particular feature of the invention is one which comprises:

from 25 to 60Z by weight of condensed phosphate builder;
from 5 to 25% by weight of at least one non-ionic surfactant;
from 5 to 55% by weight of polyethylene glycol having a molecular weight of from 100 to 500;
optionally
from 1 to 25% by weight of sodium perborate or percarbonate bleach; and
a water soluble ammonium, substituted ammonium and/or alkali metal salt of tartaric and/or citric acid in an amount to give a weight ratio of condensed phosphate builder to acid or salt of from 60:1 to 10:1,
and wherein the composition comprises from 65 to 40% by weight of solid particles having an average size of less than 10 µm dispersed in a liquid medium which is correspondingly from 35 to 60% by weight of the composition.

Compositions according to the invention may suitably be made by a process which comprises milling ingredients together for example by bead milling.
The invention is illustrated by the following Examples. All parts and percentages are by weight and in the Examples weight percentages are based on the total weight of the composition unless otherwise specified.

Materials

Tripolyphosphate: is sodium tripolyphosphate.
Sodium EDTAte: is the tetrasodium salt of ethylene diamine tetra-acetic acid.
Optical brightener: is "Leucophor DUK" optical brightener from Sandoz.
CMC: is carboxymethyl cellulose sold as "Couriose" A610, degree of substitution 0.5 to 0.7, molecular weight believed to be 60000 to 100000.
A3: is "Synperonic" A3 which is the product of condensing an average of 3 moles ethylene oxide with a mixture of two parts C₁₃ primary alkanol to one part C₁₅ primary alkanol, both having some 2-methyl branching.
87K: is "Synperonic" 87K which is the product of condensing an average of 7 moles of a mixture of 92% ethylene oxide and 8% propylene oxide with a mixture of two parts C₁₃ primary alkanol to one part C₁₅ primary alkanol, both having some 2-methyl branching.
PEG 200: is Polyethylene glycol of average molecular weight 200 D

EXAMPLES 1 to 7

Liquid formulations A - H (Control sample C1 - formulation A and Examples 1 to 7 - formulations B - H) were produced by mixing together the components in the amounts given in Table 1 below in a homogeniser and then bead milling the mixtures until the solids had an average particle size of 3 µm.

TABLE 1

Components by weight percent
Formulation	A	B	C	D	E	F	G	H
Example	C1	1	2	3	4	5	6	7
Tripolyphosphate	41.5	41.0	40.5	39.5	37.5	41.0	40.5	39.5
Sodium citrate	-	0.5	1.0	2.0	4.0	-	-	-
Sodium tartrate	-	-	-	-	-	0.5	1.0	2.0
Sodium disilicate	2.0	2.0	2.0	2.0	2.0	2.0	2.0	2.0
Sodium EDTAte	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
Optical brightener	0.3	0.3	0.3	0.3	0.3	0.3	0.3	0.3
CMC	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
Titanium dioxide	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
Sodium carbonate	5.0	5.0	5.0	5.0	5.0	5.0	5.0	5.0
A3	2.5	2.5	2.5	2.5	2.5	2.5	2.5	2.5
87K	7.5	7.5	7.5	7.5	7.5	7.5	7.5	7.5
PEG 200	39.75	39.75	39.75	39.75	39.75	39.75	39.75	39.75

The dispensability of each formulation was assessed by weighing 60g of the laundry liquid into a commercially available rectangular plastic dosing device measuring ca. 6.5 x 5 x 3.5 cm which was placed in the drum of a Philips 036 washing machine on top of 3.5 kg of laundry (laboratory coats and towels). The machine was started on programme No 5 which has a 27 minute wash cycle with cold water fill, taking 10 minutes to reach the 40°C wash temperature. 10 minutes after the drum had started to roll the machine was stopped, drained and the dosing device removed. The amount of any residues left in the dosing device was recorded. This procedure was carried out at least 3 times for each formulation. The test results are set out in Table 2 below.

TABLE 2

Residues (g) after 10 mins					Mean	Std. Dev.
A	7.09,	2.24,	4.95		4.8	2.43
B	4.89,	9.36,	11.03		8.4	3.17
C	1.38,	32.24*,	2.56		2.0	0.85
D	nil,	2.46,	nil,	25.35*	0.8	1.42
E	nil,	nil,	0.04		0.01	0.02
F	0.75,	3.07,	nil		1.3	1.60
G	nil,	8.88,	nil		3.0	5.13
H	nil,	0.17,	nil		0.06	0.10

* On these occasions the dosing device was blocked by fabric falling into it and these results were ignored in the calculation of the mean and standard deviation.

The performance at 40°C of 60 g of formulations A, D, E and H were compared in wash tests using a Zanussi FL1030 washing machine and Tees Valley Water (90 ppm Ca hardness) using standard detergency test cloths from EMPA and Krefeld. The washing machine was filled with four test pieces (10 x 10 cm) of each different type of test cloth together with 2 kg of clean cloth as ballast for each wash. Each test cloth was measured before and after washing in 10 different places to assess the increase in reflectance of the cloth. The results are set out in Table 3. TABLE 3

KREFELD 10 C EMPA 101 KREFELD 20 C EMPA 104

Formulation A 26.5 33.0 27.0 35.1

Formulation D 29.3 31.9 22.5 33.6

Formulation E 23.6 30.1 16.2 31.0

Formulation H 27.3 33.5 20.8 32.1
The above results indicate that the optimum ratio of the condensed phosphate builder to hydroxycarboxylic acid salt is probably in the range 40:1 to 20:1.

Claims

A substantially non-aqueous liquid laundry detergent composition which comprises a surfactant, a condensed phosphate builder and a hydroxycarboxylic acid containing 1 to 6 -COOH groups and 1 to 5 -OH groups or a water soluble salt of such an acid in an amount to give a weight ratio of the condensed phosphate builder to the hydroxycarboxylic acid of 60:1 to 5:1.
A composition as claimed in claim 1 wherein the water soluble salt is an ammonium, substituted ammonium and/or alkali metal salt of tartaric acid and/or citric acid.
A composition as claimed in either claim 1 or claim 2 wherein the water soluble salt is present in an amount to give a weight ratio of the condensed phosphate builder to the hydroxycarboxylic acid of 30:1 to 7:1.
A composition as claimed in any one of claims 1 to 3 wherein the condensed phosphate builder is the salt known as sodium tripolyphosphate.
A composition as claimed in any one of claims 1 to 4 wherein the condensed phosphate builder is present in an amount of 25 to 60% by weight of the total composition.
A composition as claimed in any one of claims 1 to 5 wherein the surfactant includes at least one non-ionic surfactant which is the reaction product of a C_6-20 alkyl amine; a C_6-20 alkyl, alkyl phenol; or a C_6-20 alkanol; with from 1 to 10 moles of ethylene oxide per mole of amine, alkyl phenol or alkanol respectively, in an amount of from 5 to 25% by weight of the composition.
A composition as claimed in any one of claims 1 to 6 which additionally includes a bleach which is an alkali metal perborate or percarbonate in an amount of 1 to 25% by weight of the composition.
A composition as claimed in any one of claims 1 to 7 which additionally includes polyethylene glycol having a molecular weight of 100 to 1500 D in an amount of 5 to 55% by weight of the composition.
A composition as claimed in any one of claims 1 to 8 which comprises a dispersion of solid particles having an average size of less than 10 µm in a liquid medium and in which the solid content of the composition is from 40 to 65% by weight and correspondingly the liquid medium 60 to 35% by weight of the composition.
A substantially non-aqueous liquid laundry detergent composition as claimed in claim 1 which comprises:
from 25 to 60% by weight of condensed phosphate builder;

from 5 to 25% by weight of at least one non-ionic surfactant;

from 5 to 55% by weight of polyethylene glycol having a molecular weight of 100 to 1500 D; optionally from 1 to 25% by weight of sodium perborate or percarbonate bleach; and

a water soluble ammonium, substituted ammonium and/or alkali metal salt of tartaric and/or citric acid in an amount to give a weight ratio of condensed phosphate builder to acid or salt of from 60:1 to 10:1,

and wherein the composition comprises from 40 to 65% by weight of solid particles having an average size of less than 10 µm dispersed in a liquid medium and which is correspondingly from 60 to 35% by weight of the composition.