CA1044982A - Detergent powder production - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

In a process of manufacturing a spray-dried detergent powder having a high proportion of its detergent-active material in the form of a nonionic surfactant, the tendency of this powder to autoxidise can be counteracted by incorporating into the slurry (a) an alkaline material in an amount equivalent to at least 5% by weight of sodium oxide and (b) from 1/2 to 6% by weight of an alkanolamide.
The weights are based on the weight of the spray-dried powder. An example of a suitable alkaline material is alkaline sodium silicate.

Description

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This invention relates to ~ process ~or the production of a detergent powder and to -the powders the~-selves.
Spray-dried deterge~t powder~ co~taining a nonionic surfaotant a9 the major detergent-active compone~t ~that is more tha~ 50% by weight of the to-tal detergent active material) have recently been i~troduced ~o the ~arket i~ Britain. ~hese powders have a very good washing performance but they are not easy to manu~acture.
One of the difficulties which arises during -the prepara-tio~
of the spray-dried portion o~ the powcler ~herea~ter referred to as the base powder) i9 that it can au-to-oxidise under normal spray-drying tower temperature conditions. ~his is not a feature of conve~tional alkyl be~ze~e sulpho~ate-based powders.
We have now discovered that the autoxidation temperature or the time to autoxidation at a given -temperature of detergent base powders o~ high nonionic content can be increased substantially by incorporting a relatively high level of c~n alkanola~ide into the slurry a~d by enJuri~g that the slurry re~ains 3u~ficiently alkali~e.
Accordingly, the present i~ventio~ provides a proce~s for the production o~ a detergent base powder oontaining a nonionic sur~actant as the ma~or deterge~t-active ingredien-t which comprises spray drying a slurry comprising part or all of the,nonionic surfactant, an alkaline material in an amount equivalent to,at least 5% of sodium oxide, c~nd from ~ to 6%
of an,alkanolamide,~the~ercentages being expressed as proportions o~the base powder.; ; ~,l ~ The invention also provides a base powder produced by the process.

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` C 7s9 9~32 The problem o~ autoxidation varies i~ degree ~rom one specific no~ionic sur~actant to another. Whilst we consider that the measures suggested in this speci~ication will be efiective with all ~onionic sur~actants i~ reducing the autoxidatio~ temperature~ or the time to autoxidation at a give~ temperature, clearly when using those nonionic sur~actants ior which autoxidation i9 not a severe problem, the benefit obtai~ed ~ro~ t~e inventio~ will be reduoed.
We have ~ound that the inventio~ is particularly adva~tageous when the ~ollowing no~ionic suriactants are used:-1. Nonylphenol 8,10,12 and 15 (moles) ethyleneo~ide condensates 2. ~ergitol 1~-S-70 9,12 and 15

3. Tergitol 45-S-7, 9,10,12 and 15

4. Dobanol 25-7,9,12 and 15 ~ 5. Dobanol 45-7,9,1~ and 15 ~ra~ ~1ark) -~ 6. Acropol~35-7,991~ and 15 7. Al~ol 12/14 and 14/12-7,9,12 and 15 8. Synperonic 7,9,11 and 15 ~ergitols (llrade Mark) are a Unlon Carbide ~erie~
of Cll_l5 and C14_15 9econdary alcohol ethoxylates.
Dobanols ~rade Mar~) are a Shell ~eries o~ pri~ry C12 1~ alcohol ethoxylates containing about 20~d branched material.
Acropols are a serie~ of Cl3_15 Oxo alcohol ethoxylates manu~ac-tured by Ugine-Kuhlman. The alcohols are 70% C13 and 30~o C15 contai~ing 25% of d methyl branched material and 10~ o~ ethyl branched material. ~he same materials are also sold under the Ukanil Trade Mark.

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82 ~ ~sg Alfols 12~14 and 1~112 (Trade Mark) are a series of Condea Ziegler primary C12_1~ and Cl~ l2 alcohol ethoxylates.
Synperonics (Trade Mark) are an ICI series of

- 5 C13 15 alcohol ethoxylates, co~-taining 670/o C15 and 33% C
alcohols~ 45-~5~o of which are alkyl blranched, ~09tly methyl branched alcohols.
The designation.7,9,10,12 and 15 refersto the number o~ moles o~ ethylene oxide per mole of alcohol.
The term "nonionic sur~actant" as used i~ this specification i9 intended to re~er in general to lo~g chain ethoxylates of alcohols and phenols and simllar compounds.
It does not include alkanolamides~ which in some cases have been included within the general nonionic surfactant ¢lass.
This invention is relevant to the preparation o~
spray dried base powders containing ~rom about 10 to about r.
20% by weight o~ nonionic surfactant preierably about 13 to about 18~ by weight. A~ter adding the normal proportio~
of dry-dosed ingredients, -this will produce a ~inished detergent powder having a nonionic sur~actan-t content o~ from about 7 to 14~ by weight.
All Or this nonionic surPactant material may be i in.corporated in the slurry to be spray dried~via the crutcher or some or all o~ it may be injected directly into a slurry of the other ingredients immediately prior to spray-drying.
The type o~ al~anolamide uséd as in the compositions o~ the invention. is not believed to be critical. ~hus mono- an.d di- alkanolamides can be used, as ca~ alkanola~ides derived ~rom ~atty acids o~ dif~erent chain leng-ths and those derived~~rom alkanolamines containing various di~erent alkyl groups as well as those containing polyoxyethyllene/
polyoxypropylene chains. Suitable alkanolamides include 4~
lauric monoethanolamide, lauric diethanolamide, palm kernel monoethanolamide (PKEA), coconut monoethanolamide (CEA), caprylic monoethanolamide, caprylic diethanolamide, capric diethanolamide, tallow monoethanolamide and lauric mono-isopropanolamide and mixtures thereof.
The process of the invention requires the presence, in the crutcher slurry, of an alkaline material in an amount equivalent to at least 5% of sodium oxide. In considering whether a slurry meets this requirement, the contribution to the alkalinity of a phosphate builder salt should be ignored.
Thus when the slurry contains sodium tripolyphosphate, sodium pyrophosphate or sodium orthophosphate, although these salts have an alkaline reaction, their contribution is not to be taken into account when determining the sodium oxide equivalen-t of the alkaline material.
Preferred alkaline materials are sodium silicate having an SiO2:Na2O ratio of from 1.6:1 to 2:1, sodium carbonate and sodium hydroxide.
The aqueous slurry to be spray dried may contain materials other than those already mentioned. For example it may contain small amounts, for example up to about 5% based on the weight of the base powder of an anionic surfactant such as an alkyl sulphate, an alkyl benzene sulphonate or a soap.
Mixtures of tallow and coconut soaps are preferred. An example of a suitable mixture is from 8 to 9 parts of tallow soap and from 2 to 1 part of coconut oil soap.
The aqueous slurry will also usually contain a builder salt, preferably a phosphate builder salt such as sodium tripolyphosphate, in an amount sufficient to constitute from about 25 to about 60~, preferably about 40 to about 60% of ~ _ 5 _ .'~

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the base powder.
The aqueous slurry will also contain minor ingredients in conventional amounts. These will include anti-redeposition agents, fillers, fluorescers, chelating agents and anti-oxidants. It will also contain water.

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~ C 759 In the ~ollowing examples and tables the e~fect of alkanolamides and o~ alkaline materials in stabilising ds-tergent powders having a nonionic surfactant as the ma~or detergent-active ingredient i9 shown.
The method by which the time taken for a powder to autoxidise at a given temperature is measured i9 a modification o~ the method o~ PC Bowes ~nd A Cameron described in J Appl~Chem. and Biotechnol, 1971. This method involves suspending cubic open-topped baske-ts co~taining the powder in a~ oven set to a given temperature. The powder has a thermocouple embedded in it, connec-ted to a chart recorder. When autoxidation sets i~ a rapid rise i~
temperature occurs. Unless o-therwise indicated, the present experi~ents are conducted using a cube o~ 10 cm side and an oven temperature o~ 150C.
Example 1 Slurries having formulae as detailed below were made up and spray-dried.
~0 by wo~ight o~ base powder Component of Slurry A B C D ~ F
Nonionic suriactant 16.116.1 16.1 16.1 16.116.1 Anionic suriactant 6.03.0 6.0 6.0 3.06.0 Coconut ethanolamide (CE~) 2.3 2.3 2.3 - - 2.3 Sodium tripolyphosphate42.342.3'`42.3~ 42.3 54.347.5 Sodium carbonate - - - - - 1,5 Sodium silicate 15.015.0 7.5 15.0 7.57.5 (2.0 : 1?
Sodium hydroxide - - 5.0 Moisture and minorto 100.0 100.0 lOOoO 100~0 100~0 100~0 ingredients Autoxidation time ~hrs) ~ 48~48 >48 8 2 8 ~4" basket, 150 C) Na20 equivalen~t ~ 5 ~5 ~5 ~ 5 2.53.1

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Powders formed from slurries A, B and-C which are in accordance with the invention demonstrate acceptably long times to autoxidation, whereas those formed from slurries D, E and F which are included for comp~rative purposes and which are low in alkanolamide or alkaline material, do not.
Base powders A, B and C may be converted into finished detergent powders by the usua:l post-dosing techniques. For example the following dose may be added:
Dosed component % by weight of Finished Powder Speckles 7.~
Post-dosed ethanolamide 2.2 Sodium perborate 2~.5 Perfume 0.2 An additional factor which we have found can reduce the autoxidation temperature or the time to autoxidation at a given temperature is the introduction into the slurry of certain reducing agents, particularly sGdium sulphite or sodium thiosulphate or a mixture thereof. Both of th~se reducing agents are particularly advantageous since they are oxidised to sodium sulphate which is present in many detergent formulations as a filler. Thus introduction of such a reducing agent into the slurry does not result in the finished detergent powder containing undesirable material. Amounts of reducing agents of from about 1 to about 7% have been found to have some effect in inhibiting autoxidation.

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c 75g Example 2 Component of Slurry % by weight o~ base powder G H
. _ _ _ _ Nonionic surfactant 16.2 16~2 16.2 Coconut soap 300 3.0 3.0 Coconut ethanolamide 2.3 2.3 203 Sodium tripolyphosphate 54.8 54.8 54~8 Sodium silica$e (2.0 : 1)7.6 7.6 7.6 - Sodium sulphite 2.3 - -Sodium thiosulphate - 6.6 Moisture and minor ingredients to 100 to 100 to 100 Autoxidation time (hr~) > 48 > 48 8 (10 cm basket, lS0 C) We have discovered that a further measure which can be taken to prevent or substantially reduce autoxidation is to ensure that the bulk density of the spray-dried powder is as high as possible. Whilst the precise bulk density which can be achieved will vary from composition to composition, we have found that bulk densities above about 0.35 gm/ml have a substantial effect in reducing autoxidation.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a process for the production of a particulate detergent base powder as herein defined, comprising forming an aqueous slurry containing a nonionic surfactant as the major detergent-active ingredient and spray-drying it to form a particulate detergent base powder, the improvement which comprises reducing the extent of autoxidation of the nonionic surfactant by incorporating in the slurry an alkaline material in an amount equivalent to at least 5% of sodium oxide and from 1/2 to 6% of an alkanolamide, the amount being expressed by weight of the particulate detergent base powder.

2. In a process according to claim 1, the further improvement which comprises incorporating a part of the nonionic surfactant into the slurry by direct injection.

3. In a process according to claim 1, the further improvement which comprises incorporating into the slurry an alkaline sodium silicate having an SiO2:Na2O ratio of from 1.6 to 2:1 to 1 as the alkaline material.

4. In a process according to claim 1, the further improvement which comprises incorporating into the slurry sodium carbonate or sodium hydroxide as the alkaline material.

5. In a process according to claim 1, the further improvement which comprises incorporating into the slurry palm kernel monoethanolamide as the alkanolamide.

6. In a process according to claim 1, the further improvement which comprises incorporating into the slurry coconut mono-ethanolamide.

7. In a process according to claim 1, the further improvement which comprises incorporating into the slurry tallow mono-ethanolamide.