DETERGENT COMPOSITIONS

Description

TECHNICAL FIELD

[0001] The present invention relates to particulate detergent compositions of high bulk density containing anionic and nonionic surfactants and zeolite builder.

BACKGROUND AND PRIOR ART

[0002] EP 544 492A (Unilever) discloses detergent powders of high bulk density comprising an organic surfactant system (ethoxylated nonionic surfactant plus primary alcohol sulphate), zeolite builder, and other optional ingredients. The ethoxylated nonionic surfactant, which is the predominant component (at least 60 wt%) of the surfactant system, has a degree of ethoxylation not exceeding 6.5, preferably from 3 to 6.5 and more preferably from 4 to 5.5. This high-performance surfactant system gives excellent detergency, and the use of relatively high levels of zeolite allows the formulation of free-flowing powders containing high levels of these mobile surfactants.

[0003] These compositions are representative of the recent trend towards powders of high bulk density, prepared by processes that eliminate, or do not introduce, the porosity typical of traditional spray-dried powders. These include post-tower densification of spray-dried powders, and, more preferably, wholly non-tower routes involving dry-mixing, agglomeration, granulation and similar processes.

[0004] With formulations of this type, however, some problems have been experienced in the delivery of the active ingredients of the powder to the wash in an automatic washing machine. Delivery is a two-step process: the first step is the dispensing of the powder into the wash liquor, either from the dispenser drawer of the washing machine or from a dispensing device (a wash ball or similar) supplied by the powder manufacturer; and the second is dissolution of the powder once it arrives in the wash water.

[0005] It has surprisingly been found that in high bulk density powder of the type mentioned above, delivery is greatly improved by the use of a nonionic surfactant having a higher degree of ethoxylation, provided that a citric acid salt is also present.

[0006] Citrates are well known as detergency builders used to supplement zeolites. Their use in zeolite-built powders is disclosed, for example, in EP 313 143A, EP 313 144A, EP 448 297A and EP 448 298A (Unilever); GB-A-1 408 678, EP 1310A, EP 1853B, EP 326 208A, EP 456 315A and WO 91 15566A (Procter & Gamble); DE 2 336 182C (Lion); and GB 2 095 274B (Colgate).

[0007] EP-A-0508034 discloses a granular detergent composition which is characterised by containing polyvinylpyrrolidone to give good dye transfer-inhibition effects without impairment of particulate soil removal. It is mentioned that citric acid may be used as a carboxylate chelating agent.

[0008] EP-A-0508358 relates to a laundry detergent composition characterised by containing an alkaline cellulase and polyvinylpyrrolidone. Citrates may be used as builder.

[0009] However, the use of citrate in the presence of specific nonionic surfactant to improve the dissolution of a high bulk density detergent powder has not been described in literature.

DEFINITION OF THE INVENTION

[0010] The present invention accordingly provides a particulate detergent composition which is not the direct product of a spray-drying process, the composition having a bulk density of at least 650 g/l and comprising:

(a) from 15 to 50 wt% of a surfactant system consisting essentially of

(i) ethoxylated nonionic surfactant which is a primary C₈-C₁₈ alcohol having an average degree of ethoxylation within the range of from 5.2 to 8.0,

(ii) primary alcohol sulphate,

(iii) optionally not more than 25 wt% (based on the surfactant system) of alkylbenzene sulphonate,

(b) from 20 to 70 wt% (anhydrous basis) of alkali metal aluminosilicate builder,

(c) from 5 to 40 wt% of a water-soluble salt of citric acid,

(d) optionally other detergent ingredients to 100 wt%,

wherein the detergent composition contains at least 10 wt% (in total, based on the whole composition) of ethoxylated nonionic surfactant.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The high bulk density particulate detergent compositions of the invention contain as essential ingredients:

(a) a defined surfactant system,

(b) an aluminosilicate builder,

(c) a citric acid salt.

[0012] Other optional ingredients may be present as necessary or desired.

Examples

[0013] The invention is further illustrated by the following non-limiting Examples, in which parts and percentages are by weight unless otherwise stated.

Test methods used in the Examples

[0014] Delivery into the wash, dispersion and dissolution characteristics were assessed by means of three different tests.

Test 1: cage test

[0015] Delivery characteristics of the powders were compared using a model system which simulates the delivery of a powder in an automatic washing machine, under more adverse conditions (low temperature, minimal agitation) than those normally encountered in a real wash situation.

[0016] For this test a cylindrical vessel having a diameter of 4 cm and a height of 7 cm, made of 600 micrometre pore size stainless steel mesh, and having a top closure made of Teflon and a bottom closure of the mesh just described, was used. The top closure had inserted therein a 30 cm metal rod to act as a handle, and this handle was attached to an agitator arm positioned above 1 litre of water at 20°C in an open container. By means of this agitator apparatus the cylindrical vessel, held at 45 degrees, could be rotated through a circle with a 10 cm radius over a period of 2 seconds and allowed to rest for 2 seconds, before the start of the next rotation/rest cycle.

[0017] A 50 g powder sample was introduced into the cylindrical vessel which was then closed. The vessel was attached to the agitator arm which was then moved down to a position such that the top of the cylindrical vessel was just below the surface of the water. After a 10 second delay, the apparatus was operated for 15 rotation/rest cycles.

[0018] The cylindrical vessel and handle were removed from the water and and the vessel detached from the handle. Surface water was carefully poured off, and any powder residues transferred to a preweighed container and dried for 24 hours at 100°C. The weight of dried residue as a percentage of the initial powder weight (50 g) was then calculated.

Test 2: delivery device test

[0019] Delivery characteristics of the powders were also compared using a model system which emulates the delivery of a powder in an automatic washing machine from a flexible delivery device of the type supplied with Lever's Persil (Trade Mark) Micro System powder in the UK: a spherical container of flexible plastics material having a diameter of approximately 4 cm and a top opening of diameter approximately 3 cm.

[0020] In this test the delivery device was attached in an upright position (opening uppermost) to an agitator arm positioned above water. By means of this apparatus the device could be moved vertically up and down through a distance of 30 cm, the lowest 5 cm of this travel being under water. Each up or down journey had a duration of 2 seconds, the device being allowed to rest 5 cm under water for 4 seconds at the lowest position, and at the highest position being rotated through 100° and allowed to rest in the resulting tilted orientation for 2 seconds before redescending. 5 litres of water at a temperature of 20°C were used.

[0021] A preweighed powder sample was introduced into the device in its highest position, and the apparatus then allowed to operate for six cycles and stopped when the device was again in its highest position. Surface water was carefully poured off, and any powder residues transferred to a preweighed container. The container was then dried at 100°C for 24 hours, and the weight of dried residue as a percentage of the initial powder weight calculated.

Test 3: black pillowcase test

[0022] A washing machine test was also used to determine the extent that insoluble residues were deposited on washed articles. The machine used was a Siemens Siwamat (Trade Mark) Plus 3700 front-loading automatic washer.

[0023] A 100 g dose of powder was placed in a flexible delivery device as described previously. The delivery device was placed inside a black cotton pillowcase having dimensions of 30 cm by 60 cm, taking care to keep it upright, and the pillowcase was then closed by means of a zip fastener. The pillowcase containing the (upright) delivery device was then placed on top of a 3.5 kg dry cotton washload in the drum of the washing machine.

[0024] The machine was operated on the "heavy duty cycle" at a wash temperature of 40°C, using water of 15° French hardness and an inlet temperature of 20°C. At the end of the wash cycle the pillowcase was removed, opened and turned inside out, and the level of powder residues on its inside surfaces determined by visual assessment using a scoring system of 1 to 5: a score of 5 corresponds to a residue of approximately 75 wt% of the powder, while 1 indicates no residue. A panel of five assessors was used to judge each pillowcase and allot a score. With each powder the wash process was carried out ten times and the scores were averaged over the ten repeats.

EXAMPLE 1, COMPARATIVE EXAMPLES A to C

[0025] Four detergent powders of high bulk density were prepared to the formulations shown in Table 2. Base powders were prepared using a continuous high-speed mixer/granulator, and other ingredients were postdosed as shown. The sodium citrate, where present, was postdosed as particulate sodium citrate dihydrate having an average particle size of about 800 µm.

[0026] All powders contained PAS, nonionic surfactant, and zeolite builder. Comparative Example A and Example 1 contained sodium citrate; Comparative Example A contained 7EO and 3EO nonionic surfactants, while Example 1 was a similar formulation containing only 7EO nonionic surfactant to the same total level. Comparative Examples B and C were two similar compositions containing no sodium citrate.

[0027] Table 3 shows the powder properties and delivery characteristics of the powders. Comparison of Examples A and 1 shows that changing the nonionic surfactant to an all-7EO system in a citrate-containing formulation substantially improved delivery characteristics. Comparison of Examples B and C showed that no such improvement was observed when citrate was absent.

Table 2:

formulations
Example	A	1	B	C
Base
CocoPAS	6.37	6.37	5.81	5.81
Nonionic 7EO	6.37	14.42	5.81	13.17
Nonionic 3EO	8.05	-	7.35	-
Zeolite MAP	39.49	39.20	36.04	35.77
Sodium carbonate	1.05	1.05	0.96	0.96
Fatty acid soap	2.37	2.37	2.04	2.16
SCMC	0.98	0.98	0.89	0.89
Moisture	5.32	5.61	4.98	5.12
Total	70.00	70.00	63.88	63.88

Postdosed
Sodium citrate (2 aq)	23.47	23.47	-	-
Sodium percarbonate	-	-	20.50	20.50
TAED granules	-	-	4.75	4.75
Catalyst granules	-	-	2.40	2.40
Sodium silicate	-	-	2.90	2.90
Antifoam/ fluorescer	3.15	3.15	3.00	3.00
EDTMP (Dequest 2047)	1.43	1.43	0.37	0.37
Enzymes	1.50	1.50	1.75	1.75
Perfume	0.45	0.45	0.45	0.45

Table 3:

properties
Example	A	1	B	C
Nonionic surfactants
wt% 7EO	44	100	44	100
wt% 3EO	56		56
average EO	4.77	7.0	4.77	7.0

Powder properties
Bulk density (g/l)	914	899	890	898
wt% fines	5.2	3.0	5.4	1.5

Delivery properties
Test 1 (wt% residue)	56	32	52	70
Test 2 (wt% residue)	31	0	15	12
Test 3 (score 1-5)	1.0	0.4	1.0	1.5
Insolubles at 20°C	5.5	2.2	3.4	4.2

Example 2

[0028] A composition was prepared having a formulation corresponding to that of Example 1 but containing the following surfactant system:

CocoPAS	6.37
Nonionic 7EO	8.65	(60%)
Nonionic 3EO	5.77	(40%)

[0029] The composition gave zero residues when dosed via the dispenser drawer of three different automatic washing machines (Phillips, Zanussi, Siemens).

Examples 3 to 6

[0030] Two further machine wash formulations in accordance with the present invention are shown below in Examples 3 and 4.

	3	4	5*	6*
CocoPAS	8.47	10.60	12.71	13.77
Nonionic 6.5EO	12.71	10.58	8.47	7.41
Soap	1.95	1.63	1.30	1.14
Zeolite MAP	34.34	26.29	18.33	14.35
Sodium carbonate	1.44	1.80	2.16	2.34
SCMC	0.89	0.74	0.59	0.52
Moisture, salts	1.80	2.26	2.71	2.93
Sodium citrate	7.08	14.80	22.42	26.23
Antifoam/fluorescer	3.00	3.00	3.00	3.00
Silicate	3.67	3.67	3.67	3.67
Percarbonate	16.85	16.85	16.85	16.85
TAED	3.75	3.75	3.75	3.75
Mn catalyst	1.27	1.27	1.27	1.27
EDTMP	0.37	0.37	0.37	0.37
Enzymes	1.75	1.75	1.75	1.75
Perfume	0.65	0.65	0.65	0.65

*not within the scope of the claim

Claims

1. Particulate detergent composition which is not the direct product of a spray-drying process, the composition having a bulk density of at least 650 g/l and comprising:

(a) from 15 to 50 wt% of a surfactant system consisting essentially of

(i) ethoxylated nonionic surfactant which is a primary C₈-C₁₈ alcohol having an average degree of ethoxylation within the range of from 5.2 to 8.0,

(ii) primary alcohol sulphate,

(iii) optionally not more than 25 wt% (based on the surfactant system) of alkylbenzene sulphonate,

(b) from 20 to 70 wt% (anhydrous basis) of alkali metal aluminosilicate builder,

(c) from 5 to 40 wt% of a water-soluble salt of citric acid,

(d) optionally other detergent ingredients to 100 wt%

wherein the detergent composition contains at least 10 wt% (in total, based on the whole composition) of ethoxylated nonionic surfactant.

Ansprüche

1. Eine teilchenförmige Waschmittelzusammensetzung, die nicht das direkte Produkt eines Sprühtocknungsverfahrens ist, wobei die Zusammensetzung eine Schüttdichte von zumindest 650 g/ℓ aufweist und enthält:

(a) Von 15 bis 50 Gewichtsprozent eines Surfactant-Systems, bestehend im wesentlichen aus

(i) ethoxyliertem nichtionischen Surfactant, welches ein primärer C₈-C₁₈-Alkohol ist mit einem durchschnittlichen Ethoxylierungsgrad innerhalb des Bereiches von 5,2 bis 8,0,

(ii) Primäres Alkoholsulfat,

(iii) wahlweise von nicht mehr als 25 Gewichtsprozent (basierend auf dem Surfactant-System) Alkylbenzolsulfonat,

(b) von 20 bis 70 Gewichtsprozent (wässerige Basis) Alkalimetallaluminosilicat-Builder,

(c) von 5 bis 40 Gewichtsprozent eines wasserlöslichen Salzes von Citronensäure,

(d) wahlweise andere Waschmittel-Bestandteile bis zu 100 Gewichtsprozent, wobei die Waschmittelzusammensetzung mindestens 10 Gewichtsprozent (insgesamt, auf die gesamte Zusammensetzung bezogen) ethoxyliertes nichtionisches Surfactant enthält.

Revendications

1. Composition détergente particulaire qui n'est pas le produit direct d'un procédé de séchage par pulvérisation, la composition présentant une masse volumique au moins égale à 650 g/l et comprenant :

(a) de 15 à 90 % en masse d'un système tensioactif composé essentiellement de :

(i) un agent tensioactif non ionique éthoxylé qui est un alcool primaire en C₈-C₁₈ présentant un degré moyen d'éthoxylation compris dans la gamme allant de 5,2 à 8,0 ;

(ii) un sulfate d'alcool primaire ;

(iii) optionnellement pas plus de 25 % en masse (sur la base du système tensioactif) d'alkylbenzènesulfonate,

(b) 20 à 70 % en masse (base anhydre) d'un adjuvant aluminosilieate du métal alcalin,

(c) 5 à 40 % en masse d'un sel d'acide chimique hydrosoluble,

(d) optionnellement d'autres ingrédients détergents, jusqu'à 100 % en masse, dans laquelle la composition détergente contient au moins 10 % en masse (au total sur la base de la composition dans son ensemble) de tensioactif non ionique éthoxylé.