AU620381B2 - Detergent powders and process for preparing them - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION Form

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: p 0 6 O TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: UNILEVER PLC UNILEVER HOUSE

BLACKFRIARS

LONDON EC4

ENGLAND

0 00I Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: DETERGENT POWDERS AND PROCESS FOR PREPARING THEM The following statement is a full description of this invention including the best method of performing it known to me:- 1: Li i .i i: C 3224 (R)

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DETERGENT POWDERS AND PROCESSES FOR PREPARING THEM TECHNICAL FIELD The present invention relates to detergent powders prepared at least in part by spray-drying and intended for use in drum-type front-loading washing machines.

The invention is of especial applicability to powders containing no, or reduced levels of, phosphate builders 0 and to powders of high bulk density.

0400 1 0 BACKGROUND 000 In recent years the trend in detergent compositions has 0been towards reducing or eliminating phosphate builders.

The replacement of sodium tripolyphosphate as a builder 15 in detergent powders by its most popular zero-phosphate 0 substitute, crystalline sodium aluminosilicate (zeolite), has led to a number of difficulties with the o o structure and physical properties of the powder. One such problem that has been encountered is the tendency of zeolite-built powders to dispense less well in frontooo loading automatic washing machines than do their 0000 phosphate-built counterparts; a higher proportion of the 00 powder dosed into the machine is left behind in the dispenser, leading to product wastage and clogging. This problem is especially marked at low wash temperatures.

The tendency towards poor dispensing has been exacerbated by the recent trend in the detergents industry towards higher bulk density powders.

We have now found that the dispensing behaviour of those powders that are especially prone to this problem may be substantially imaproved by including in the powders low levels of certain hydrophobic materials, either via the slurry or by subsequent spray-on.

C 0* 2 b Surprisingly, the incorporation of these materials via the slurry also improves powder structure and, when anionic surfactant is present, raises the bulk density.

DEFINITION OF THE INVENTION In a first aspect, the invention provides a spray-dried detergent powder being substantially free from inorganic phosphate and comprising at least 5% by weight of one or more anionic surfactants, from 20 to 80% by weight of crystalline or amorpiious aluminosilicate detergency builder and no more than 10% by weight of alkali metal silicate, characterised in that the powder further comprises from 0.1 to 6.0% by weight of a paraffin wax which is waterinsoluble and substantially insoluble in anionic and 0 e" nonionic surfactants and has a melting point within the Goo 15 range of from 30 to 100 0 C and a contact angle to water of at least 750 aoo i~ 0.00 In a second aspect, the invention provides a process for o o the preparation of a detergent powder being substantially free from inorganic phosphate and comprising at least 5% by weight of one or more anionic surfactants, from 20 to by weight of crystalline or amorphous aluminosilicate nooe 0o detergency builder and no more than 10% by weight of CC D alkalimetal silicate, the process including the step of o spray-drying an aqueous slurry, characterised in that the C 00 powder further comprises a paraffin wax which is waterinsoluble and substantially insoluble in anionic and :oa 0 nonionic surfactants and has a melting point within the range of from 30 to 100 0 C and a contact angle to water of at least 750, and in that this paraffin wax is incorporated in the slurry or sprayed onto the powder in an amount of from 0.1 to 6.0% by weight based on the powder.

I~ C 3224 (R) 3 @Or pciOd-9 ofC 1 minuWte.

PRIOR ART Detergent compositions containing foam control systems that include hydrocarbon waxes are disclosed in EP 87 233A, EP 109 247A and EP 206 522A (Unilever); GB 1 492 938, GB 1 492 939, GB 2 040 982B, EP 8 829A, EP 8 830A and JP 56 034797A (Procter Gamble); 0 DE 3 436 194A, US 4 590 194 and EP 150 386A (Henkel).

SUS 4 196 104 (Procter Gamble) discloses spraying an oo°0 antistatic composition comprising a quaternary ammonium compound and a paraffin wax (as dispersion inhibitor) oooo 0 onto detergent base granules.

DETAILED DESCRIPTION OF THE INVENTION The first aspect of the invention is a detergent powder prepared at least in part by spray-drying. The 20 composition of the invention may be a fully formulated 0 0 detergent composition prepared wholly by spray-drying; a spray-dried base to which other ingredients may be ooo admixed to form a finished product; or a finished o product of that type, comprising a spray-dried base in 25 admixture with other ingredients.

As essential ingredients, the detergent powder of the invention contains one or more anionic and/or nonionic surfactants, and a specified hydrophobic material that influences its dispensing behaviour in a particular manner.

The composition of the invention may also contain any of the materials conventionally included in detergent compositions. These are described in more detail below.

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LLL-1 I C 3224 (R) 4 The surfactant component The total amount of surfactant present in the composition of the invention will generally range from to 40% by weight, more preferably from 10 to 30% by weight and especially from 12 to 20% by weight. These figures are typical for fully formulated detergent compositions, and where a spray-dried base forms only part of such a composition the surfactant content of 0 00 o 10 that base, as a percentage, may of course be higher.

0000 oc The invention is of especial applicability to 000o compositions containing anionic surfactant. When such C"O powders are prepared by spray-drying, the high-foaming S 15 anionic surfactant tends to cause "puffing" (entrainment of air) in the slurry, so that highly porous particles eo are formed in the spray-drying tower. These particles o, may be very crisp and free-flowing, but may be of lower 0 0 bulk density than desired. Surprisingly, the o. 20 incorporation in the slurry of an additive such as paraffin wax, in accordance with the present invention, has been found to result in an increase in bulk density.

oC. The amount of anionic surfactant present is d-toiraly at S o least 5% by weight, and may suitably be in the range of O 0

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a 25 from 5 to 30% by weight, preferably from 5 to 10% by weight, these figures again being based on a fully formulated detergent composition.

Anionic surfactants are well known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly sodium linear alkylbenzene sulphonates having an alkyl chain length of C 8

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15 primary and secondary alkyl sulphates, particularly sodium C 12

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1 primary alcohol sulphates; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.

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C 3224 (R) Preferably, the composition of the invention also contains one or more nonionic surfactants. Nonionic surfactants that may be used include the primary and secondary alcohol ethoxylates, especially the C 12

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1 primary and secondary alcohols ethoxylated with an average of from 3 to 20 moles of ethylene oxide per mole of alcohol.

The weight ratio of anionic surfactant to nonionic *oSoo 10 surfactant is preferably at least 0.67:1, more o a o preferably at least 1:1, and most preferably within the range of from 1:1 to 0:1, in order to obtain the optimum 0000 detergency and foaming properties appropriate for 0oo 00 front-loading automatic washing machines. These ratios 0 15 of course apply to fully formulated products. A spraydried base that is to form only part of a product may contain a lower proportion of, or no, nonionic 00 0 O o surfactant, the balance of the nonionic surfactant Ea being added after the spray-drying tower.

o to 0 0 6V The hydrophobic material .oo 0 The characterising feature of the composition of the 5present invention is the presence of a low level S 25 by weight) of a hydrophobic material. The hydrophobicity of the material is expressed in terms of its contact angle to water, which must be at least preferably at least 85°. Hydrocarbons are especially preferred.

The melting point of the material is also important: it appears that the additive should be solid at ambient temperature but liquid at slurry-processing temperature (generally in the range of from 60 to 100"C). The melting point of the additive should lie within the range of from 30 to 100°C, preferably from 40 to Preferred materials are paraffin waxes melting within r u C 3224 (R) 6 the specified range, and preferably melting within the range of from 50 to 60°C. Paraffin oil liquid at ambient temperature has been found to be ineffective in the context of the present invention, and also tends to give wet, sticky powders with unacceptable flow properties.

It is also essential that the hydrophobic material be substantially insoluble in the anionic and nonionic %o°i 10 surfactant system present in the composition: the S microcrystalline waxes of GB 1 492 938 and GB 1 492 939 oo,« (Procter Gamble) are stated to be chosen for their solubility in the surfactant present, and are S unsuitable for use in the present invention for that reason as well as for the reason that their melting points are too high.

0 0 a The hydrophobic material is preferably present in an amount of from 0.2 to 4% by weight. In a fully o 20 formulated product the optimum level for paraffin wax appears to be from 0.3 to 2% by weight.

Incorporation of the hydrophobic material 25 The composition of the invention is prepared by a process which includes the step of spray-drying an aqueous crutcher slurry. This slurry will normally contain all those desired ingredients sufficiently heat-stable to survive the spray-drying process, notably anionic surfactants, builders, inorganic salts, sodium silicate, polymers and fluorescers. More heatsensitive ingredients can be postdosed to, or sprayed onto, the spray-dried base.

There are two m-.thods by means of which the hydrophobic material characteristic of the invention may be 1 incorporated. It may be included in the slurry, in which C 3224 (R) 7 case it is preferably used in an amount of from 0.2 to by weight, more preferably from 0.3 to 2.0% by weight, based on the final powder including any postdosed ingredients. It may be advantageous to premix the hydrophobic material with surfactant, especially nonionic surfactant, before admixture with other slurry ingredients.

It has surprisingly been found that incorporation of °o 10 paraffin wax via the slurry not only improves dispensing 000.

00 behaviour, but also improves powder structure and, when anionic surfactant is present, also raises the bulk 0090 a density. Flow properties are not detrimentally affected.

15 The second method by which the hydrophobic material may be incorporated in a detergent composition of the o invention is by spraying it in liquefied form onto the o spray-dried powder. If the final product is to include postdosed solid ingredients, for example, sodium 20 perborate, bleach activator granules, enzyme granules or antifoam granules, the hydrophobic material should be sprayed on after addition of those ingredients so as Soa to cover the whole powder.

If desired, the hydrophobic material may be melted and sprayed directly onto the powder. The hydrophobic material is then preferably used in an amount of from to 6.0% by weight, more preferably from 3.0 to by weight.

According to a preferred embodiment of the invention, however, the hydrophobic material is premixed with nonionic surfactant to form a coating composition which may then be sprayed onto the detergent powder. Lower levels of the hydrophobic material, for example, 0.2 to preferably 0.3 to are then found to be effective. The coating composition consists essentially I C 3224 (R) 8 of 2-50% by weight of the hydrophobic material and 50-98% by weight of nonionic surfactant. In the preferred embodiment of the invention in which the hydrophobic material is paraffin wax, the coating composition desirably contains 8-15% by weight of paraffin wax and 85-92% by weight of nonionic surfactant. The paraffin wax, and if necessary the nonionic surfactant, are melted to form the coating composition, which is applied as a liquid, suitably at a 1 0 temperature of 40-60'C.

4 0 The coating composition should be substantially free of S0 S other ingredients that might interfere with the S 15 beneficial effect of the hydrophobic material on 0 15 dispensing.

Dispensing behaviour It is an essential feature of the detergent powder of the invention that the incorporation as specified above of a hydrophobic material such as paraffin wax should bring about an improvement in dispensing now behaviour. Dispensing is assessed by means of a standard test using a Philips (Trade Mark) AWB 126/7 washing machine using a 100 g powder dose and a water fill of 5 litres at 20°C flowing in over a period of 1 minute. The dry weight of powder remaining in the dispenser, in grams, then represents the weight percentage of powder not dispensed into the machine (the residue). It will be appreciated that this test is stringent, using a low water inlet temperature and flow rate, and a machine with a drawer-type dispenser which is particularly vulnerable to high residues and clogglng. According to the invention, the incorporation of the hydrophobic material should effect a reduction in the residue of at least 10 percentage points, preferably at least 20 percentage points. For the C 3224 (R) 9 purposes of comparison, a powder having essentially the same composition but with an inorganic salt (sodium carbonate or sodium sulphate) to make up the difference should be used.

Clearly an improvement of this magnitude can only be observed if the control powder exhibits poor dispensing properties. The present invention is therefore especially applicable to powders which, without the 0 10 additive, give dispenser residues of at least 10%, inore o especially at least 20%, by weight. That is especially likely to be the case if the powder is a zero-phosphate S composition built with crystalline (zeolite) or '0 amorphous sodium aluminosilicate; if it contains less d 15 than 10% sodium silicate; or if it has a bulk density I of 550 g/litre or more.

o Optional components 20 As indicated previously, the detergent powder of the invention can contain any of the ingredients conventionally present in compositions intended for the o° ~washing of fabrics in front-loading automatic washing ocao S machines. Examples of such components include inorganic and organic detergency builders, other inorganic salts, sodium silicate, bleaches, fluorescers, polymers, lather control agents, enzymes and perfumes.

If desired, the powder of the invention may contain one or more soaps of fatty acids, in addition to the nonsoap anionic surfactant mentioned above.

The powder will also contaln one or more detergency builders. The invention is of especial applicability, as previously mentioned, to low- or zero-phosphate powders containing crystalline (zeolite) or amorphous aluminosilicate. Zeolite may suitably be present in an _II C 3224 (R) amount of from 20 to 80% by weight. Other, supplementary, builders may also be present, for example, polycarboxylate polymers such as polyacrylates, acrylic-maleic copolymers, or acrylic phosphinates; momomeric polycarboxylates such as nitrilotriacetates and ethylene diamine tet. Acetates; inorganic salts such as sodium carbonate; and many other materials familiar to the skilled detergent formulator.

0 10 If desired, the powder of the invention may contain P0", sodium silicate. High levels of silicate can in themselves have a beneficial effect on dispensing, as S well as on powder structure and prevention of machine a corrosion, but are undesirable in powders containing aluminosilicate because the two components react together to form insoluble siliceous species. The 0 present invention enables the dispensing behaviour of zeolite-built powders to be improved without a Q 0D 0 S corresponding increase in the level of insoluble o 20 material. Accordingly, the invention is of especial applicability to powders containing less that 10% by weight, more especially less than 5% by weight, of 0" sodium silicate.

S" 25 Other materials that may be present in the powder of the invention include fluorescers, antiredeposition agents, inorganic salts such as sodium sulphate, enzymes, lather control agents, bleaches, bleach activators, and bleach stabilisers. These may be included in the spray-dried base powder or postdosed according to their known suitability for undergoing spray-drying processes and their compatibility with other slurry ingredients.

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

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EXAMPLES

Examples 1 to 4 Zero-phosphate detergent base powders containing various amounts of paraffin wax (melting point 52-54°C) or paraffin oil were prepared, by slurry-making and spray-drying, to the following nominal composition: 0.0 0 0 0 0 0 00 03 0 0 0 0 0 0.

0 0 0 00 00 0 0n 00 0 0 00 0 0 S0o a 0 R0 0 10 Sodium linear alkylbenzene sulphonate Nonionic surfactant Zeolite (anhydrous) Acrylic/maleic copolymer* 15 Sodium carbonate Minor ingredients Moisture Paraffin wax 0, 0.25, or paraffin oil Parts 24.0 0.83 10.0 0.5, 1.0, 51-53 parts ollowing Total *Sokalan (Trade Mark) CP5 ex BASF.

To the base powder were postdosed the ingredients: f Parts Burkeite/nonionic surfactant adjunct* 13.0 Sodium perborate monohydrate TAED granules Dequest 0.2 Enzyme granules 0.6 Lather control granules Sodium alkaline silicate Sodium carbonate 5.4 Sodium sulphate to 100.0 *as described and claimed in EP 221 776A (Unilever) 2

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insoluble in anionic and nonionic surfactants and has a melting point within the range of from 30 to 1000o and a contact angle to water of at least 750, and in that this S./2 lii

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~sl C 3224 (R) The following table shows the six compositions prepared, their dispenser residues measured in accordance with the defined test given above, and their powder properties: o 4t Ogq~ 10 000 o 0 00 00 Paraffin wax Paraffin oil Sodium sulphate Dispenser residue Bulk density (g/l) Dynamic flow rate Compressibility 3 1 A 1 2 0 0.25 0.5 0 0 0 1.65 11.32 10.87 2 20 0 80 609 755 )9 111 109 4 16 24 3 1.0 0 10.62 0 724 109 4 2.0 0 9.82 0 685

B

0 10.62 33 It will be noted that even the low level of 0.25 parts of paraffin wax effected a substantial improvement in dispensing behaviour, and no dispenser residues at all S were observed when higher levels of paraffin wax were S used. The higher levels also brought about increases in o-o 20 bulk density, and improvements in powder structure (compressibility) were observed at all levels.

The dispensing and powder properties of the spray-dried base powders of Examples 2-4 and Comparative Example A were also examined. The full formulations of these base powders were as follows: Sodium LAS 17.96 Nonionic surfactant 1.99 Zeolite (anhydrous) 47.89 Copolymer 7.89 Sodium carbonate 3.99 Minor ingredients 1.66 Moisture 18.53 Paraffin wax 0 Total 100.0 2 17.67 1.96 47.13 7.85 3.93 1.63 18.85 0.98 100.0 3 17.59 1.95 46.89 7.82 3.91 1.62 18.27 1.9 100.0 4 17.30 1.92 46.17 7.70 3.85 1.60 17.61 3.85 100.0 I .:D .U C 3224 (R) 13 The full formulation of the base powder of Comparative Example B was identical to that of Example 3, except that the paraffin wax was replaced by paraffin oil. The dispensing residues of the base powders, determined by the test described above, and their powder properties were as follows: A 2 3 4 Dispenser residue 46 0 0 0 Bulk density 540 585 525 586 10 DFR (ml/s) 108 115 117 109 o P Compressibility v/v) 36 29 31 0 The dispenser residue of the base powder of Comparative Example B was o 0 Example Go Zero-phosphate detergent powders similar to those of 0 o" Examples 1-4 but containing a higher level of anionic 20 surfactant were prepared, to the following formulations (in weight C ",Li Spray-dried base powder Sodium linear alkylbenzene sulphonate 11.1 11.1 Nonionic surfactant 1.2 1.2 Zeolite (anhydrous) 24.0 24.0 Acrylic/maleic copolymer* 4.0 Sodium carbonate 2.0 Sodium alkaline silicate 0.5 Sodium sulphate 1.3 1.3 Minor ingredients 0.83 0.83 Paraffin wax (m.pt. 52-54"C) 0 Moisture 9.50 9.95 *Sokalan (Trade Mark) CP5 ex BASF.

C 3224 (R) 14 Postdosed ingredients Burkeite/nonionic surfactant adjunct 16.09 16.09 Sodium perborate monohydrate 8.0 TAED granules 3.0 Dequest 0.75 0.75 Enzyme granules 0.5 Lather control granules 2.4 2.4 Sodium carbonate 3.27 3.27 Sodium sulphate 11.43 9.98 10 Total 100.0 100.0 o 0a The dispensing and powder properties of these products S were as follows: C S 15 Dispenser residue of base 80 0 sop of whole product 55 3 0 Bulk density 660 648 a Dynamic flow rate (ml/s) 91 97 a e 20 Compressibility v/v) 10 17 With this product, which already exhibited a very high bulk density and excellent powder properties, no a further improvement in these respects resulted from the S" 25 inclusion of paraffin wax in the base powder. A marked improvement in dispensing behaviour was, however, observed.

'a Examples 6 to 8 A zero-phosphate detergent base powder similar to that of Compacative Example A was prepared, by slurry-making and spray-drying, to the following formulation: C 3224 (R) Parts Sodium linear alkylbenzene sulphonate 9.0 18.37 Nonionic surfactant 1.0 2.04 Zeolite (anhydrous) 24.0 48.98 Acrylic/maleic copolymer* 4.0 8.16 Sodium carbonate 2.0 4.08 Minor ingredients 0.83 1.69 Moisture 8.17 16.68 *Sokalan (Trade Mark) CP5 ex BASF.

S°0 O a" 0, Samples of this base powder were post-sprayed with oo0 molten paraffin wax (melting point 52-54*C) in various S amounts, as shown in the table below. The dispensing

S

a properties of the samples, and of the base powder o 15 without wax spray-on (Comparative Example are also shown in the table.

0 0 D 6 1 8 0 0 e" Paraffin wax sprayed on: S, 20 parts 0 0.3 1.0 S% 0 0.61 2.0 3.92 Dispenser residue 37 12 10 1 040 It will be seen that the sprayed-on paraffin wax 25 effected a substantial reduction in dispenser residues: at the 2 parts level these were negligibly low.

Examples 9 to 11 The procedure of Examples 6 to 8 was repeated, but this time the paraffin wax was melted and dispersed in liquid nonionic surfactant, and the coating composition thus obtained was sprayed onto the base powder. The three coating compositions used were as follows, the parts being on the same basis as those of the base powder D, and the percentages being based on the coating composition: _i I C 3224 (R) 16 Parts Example 9: Paraffin wax 0.3 9.1 Nonionic surfactant 3.0 90.9 Example Paraffin wax 1.0 25.0 Nonionic surfactant 3.0 75.0 Example 11: Paraffin wax 2.0 40.0 o, 10 Nonionic surfactant 3.0 60.0 :Dispensing and powder properties were as follows: D 9 10 11 Wax/nonionic spray-on: 4 15 Total (parts) 0 3.3 4.0 Total on base powder) 0 6.31 7.55 9.26 o Dispenser residue 37 0 0 0 SBulk density (g/ml) 450 512 o Dynamic flow rate (ml/s) 108 105 20 Compressibility v/v) 27 21 Comparison with Examples 6 to 8 shows that when the i paraffin wax was pre-dispersed in nonionic surfactant it was effective at a lower level in improving dispensing behaviour. Bulk density and compressibility were improved even at the low level of 0.3 parts of paraffin wax.

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Claims (3)

1. A spray-dried detergent powder being substantially free from inorganic phosphate and comprising at least 5% by weight of one or more anionic surfactants, from 20 to 80% by weight of crystalline or amorphous aluminosilicate detergency builder and no more than 10% by weight of alkali metal silicate, characterised in that the powder further comprises from 0.1 to 6.0% by weight of a paraffin wax which is water-insoluble and substantially insoluble in anionic and nonionic surfactants and has a melting point within the range of from 30 to 100 0 C and a contact angle to water of at least

2. A powder as claimed in claim 1, characterised in that the paraffin wax has a contact angle to water of at "0 15 least

850. o 3. A powder as claimed in claim 1 or claim 2, characterised in that the paraffin wax has a melting point within the range of from 40 to 80 0 C. 4. A powder as claimed in any preceding claim, o 20 characterised in that the amount of paraffin wax incorporated in the powder is within the range of from 0.2 to 4.0% by weight. A powder as claimed in any preceding claim, characterised in that it has a bulk density of at least 450 g/litre. 6. A powder as claimed in claim 5, characterised in that it has a bulk density of at least 600 g/litre. 7. A process for the preparation of a detergent powder being substantially free from inorganic phosphate and comprising at least 5% by weight of one or more anionic surfactants, from 20 to 80% by weight of crystalline or S/d A l amorphous aluminosilicate detergency builder and no more I eA 07 K i J i range of from 30 to 100°C, preferably trom 4u Co ou Preferred materials are paraffin waxes melting within S.3 than 10% by weight of alkalimetal silicate, the process including the step of spray-drying an aqueous slurry, characterised in that the powder further comprises a paraffin wax which is water-insoluble and substantially insoluble in anionic and nonionic surfactants and has a melting point within the range of from 30 to 100 0 C and a contact angle to water of at least 750, and in that this paraffin wax is incorporated in the slurry or sprayed onto the powder in an amount of from 0.1 to 6.0% by weight based on the powder. 8. A process as claimed in claim 7, characterised in that the paraffin wax is incorporated via the slurry, in an amount of from 0.2 to 4.0% by weight based on the powder. o 9. A process as claimed in claim 8, characterised in 15 that the paraffin wax is premixed with nonionic surfactant before admixture with other slurry ingredients. o 0 0. on 10. A process as claimed in claim 9, characterised in that the paraffin wax in liquefied form is sprayed onto the spray-dried powder, in an amount of from 0.2 to 4.0% by weight based on the powder thus obtained. o 11. A process as claimed in claim 10, characterised Sin that it comprises spraying onto the powder a coating °composition consisting essentially of: 000Ol0 0 o(i) from 2 to 50% by weight of the paraffin 25 wax dispersed in (ii) from 50 to 98% by weight of nonionic surfactant, the percentages being based on the coating composition. 12. A process as claimed in claim 11, characterised in that the coating composition consists essentially of j I bforeadmxtur wih oter lurr inredints 0. I, i_-i I;i 19 from 5 to 30% by weight of paraffin wax and from 70 to by weight of nonionic surfactant. 13. A process as claimed in claim 12, characterised in that the coating composition consists essentially of from 8 to 15% by weight of paraffin wax and from 85 to 92% by weight of nonionic surfactant. DATED THIS 29TH DAY OF NOVEMBER 1991 UNILEVER PLC By its Patent Attorneys: .0 GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia. 0 00 000 0 00 *000 0C 0 0 0 0 0 00 0 0 0 4 4 C. AO i r K: AA;