EP0087233B1

EP0087233B1 - Process for producing low-sudsing detergent compositions

Info

Publication number: EP0087233B1
Application number: EP83300540A
Authority: EP
Inventors: Malcolm Nigel Alan Carter; Peter Robert Garrett; Dennis Giles; Appaya Raghunath Naik
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 1982-02-04
Filing date: 1983-02-03
Publication date: 1986-11-12
Also published as: DE3367617D1; ATE23560T1; EP0087233A1

Abstract

A process for making low-sudsing detergent powders is disclosed. The particular feature of the process is the formation of an intimate mixture of an oily or waxy substance and a defined nitrogen compound, an alpha , omega -dialkylamide alkane for example, and the subsequent spraying of the mixture onto either a carrier, or onto spray-dried detergent powder.

Description

This invention relates to a process for producing low-sudsing detergent compositions, and to the compositions produced.
Low-sudsing detergent compositions are increasing in popularity as the number of front-loading, drum-type washing machines increases, and are now widespread. They are generally in spray-dried, particulate form, although liquids are now being introduced, and are formulated with a high sudsing detergent system together with a suds-suppressant. The high sudsing detergent system is usually either an anionic detergent-active compound alone, or a combination of an anionic and a nonionic detergent-active compound. The suds-suppressant component can be selected from a wide variety of types, examples being alkyl phosphoric acid esters and their salts, hydrocarbons such as petroleum jelly and waxes, silicone oils and hydrophobed silicas, and mixtures thereof.
In DE-A-2,043,087, low-sudsing compositions containing complex nitrogen compounds as suds control agents are described. We have now discovered that if certain selected species of these compounds are intimately admixed with an oily or waxy substance and incorporated into what would otherwise be a high-sudsing spray-dried detergent composition by spraying, then excellent low-sudsing compositions are produced. This general type of process is disclosed in our published European patent application EP-A-45208, but it is not suggested there that the process would be advantageous for application of the specific suds-suppressant mixtures of this invention, as compared with, for example the through-slurry route known to the art.
Accordingly, the present invention provides a process for the manufacture of a low-sudsing detergent composition which comprises forming an essentially spray-dried detergent composition and adding a suds-suppressant to it by spraying, the suds-suppressant comprising an intimate mixture of an oily or waxy substance and an a,w-dialkylamide alkane having the structure:
where n is the integer 1 or 2.
The selected a,w-dialkylamide alkanes are α,ω•distearamide methane and a,w-distearamide ethane, (commonly known as methylene and ethylene distearamides, respectively).
Examples of oily substances are mineral, vegetable or animal oils, colourless mineral oils being preferred. Either light or heavy mineral oil or mixtures thereof may be employed but, of course, any substance used must be of low volatility at normal fabric-washing temperatures. Other oils which are suitable are sesame oil, cottonseed oil, corn oil, sweet almond oil, olive oil, wheat germ oil, rice bran oil or peanut oil, or animal oils such as lanolin, neat's foot oil, bone oil, sperm oil or cod liver oil.
Preferred waxy materials are of mineral origin, especially those derived from petroleum, including microcrystalline and oxidised microcrystalline petroleum waxes and paraffin waxes. A preferred material is petroleum jelly, (often sold under the trade mark "Vaseline" by Cheseborough-Ponds Limited), desirably one having a drop-melting point of from 20°-120°C, preferably 45-65°C. The term 'drop-melting point' as used herein is used in the sense defined in ASTM designation D127-63. Synthetic waxes, or Montan waxes, or natural waxes such as beeswax, candelilla and carnauba waxes may also be used if desired.
Any of these waxes described may be used alone or in admixture with other waxes.
The suds-suppressant combination may be added to the essentially high sudsing composition in an amount such that it forms from 0.1 to 5%, preferably 0.5 to 3.5% by weight of the final composition. The relative proportions of the a,w-dialkylamide alkane and the oily substance in the suds-suppressant combination are generally from 2.5:97.5 to 9:1, preferably 5:95 to 1:3, the ratios being expressed by weight.
The suds-suppressant combination may be mixed with a dispersing agent such as a nonionic surfactant. Typical nonionic surfactants may for example be either ethoxylated alcohols or sorbitan esters. The relative proportions of dispersing agent to the suds-suppressant combination are generally from 0.2:99.8 to 3:1.
The suds-suppressant combination may also be mixed with other antifoam ingredients such as fatty acids and their soaps, alkyl phosphoric acids and their salts with metal ions, and hydrophobed silica. The relative proportion of other ingredients to the a,w-dialkylamide alkanes is from 1:9 to 9:1.
The compositions prepared by the process of this invention will contain either an anionic, a nonionic, a zwitterionic or a cationic surfactant or a mixture of these. Other components which will normally be present include detergency builders, fabric conditioning agents, bleaching agents, bleach activators, corrosion inhibitors, anti-redeposition agents, fluorescers, stabilisers and a substantial proportion of moisture.
Typical anionic surfactants, which may be present in amounts of from about 2 to 35% by weight of the finished composition, are sodium alkylbenzene sulphonates, preferably the C_1o-C₁₄ alkyl compounds, sodium primary and secondary alkyl sulphates, preferably the C,_oC₂₂ alkyl sulphonates, sodium olefine sulphonates, preferably the C₁₀―C₁₈ sulphonates, sodium alkane sulphonates and sodium alcohol ether sulphates. Soaps of fatty acids may also be present, preferably the sodium and potassium salts of C₁₀―C₂₂ fatty acids, both saturated and unsaturated. Where soap is the sole anionic surfactant it may be present in an amount up to about 65% by weight of the finished composition, down to about 12% by weight when other anionic surfactants are present. Typical soaps which can be used are those formed from coconut oil, tallow and natural oils containing high proportions of oleic acids such as sunflower oil.
The compositions produced by the process of the invention can also contain nonionic surfactants, preferably ethoxylated primary and secondary alcohols of from 8 to 25 carbon atoms containing from 3 to 25 moles of ethylene oxide per mole of alcohol. These materials may be present in an amount of from 1 to 15% by weight, based on the weight of the finished composition.
Typical detergency builders which can be used are the water-soluble phosphates, carbonates, percarbonates and aluminosilicates, particularly the sodium and potassium salts of these compounds. Organic builders may also be used, examples being sodium carboxymethylsuccinate, sodium citrate, sodium polyacrylates and sodium nitrilotriacetate. Any of these compounds, or any other builder compound, in any suitable mixture, may be used in amounts of from 5 to 50% by weight of the finished composition.
It is emphasised that the components of the suds-suppressant must be in intimate mixture prior to spraying on to the essentially high sudsing spray-dried detergent composition, since we have discovered that if the two components are added separately, inferior suds control is produced.
The normal method for making powdered detergent compositions is to combine the spray-dried base powder with components such as sodium perborate, sodium sulphate, enzyme compositions and perfume in a dry-dosing step. This step may be performed in accordance with the invention either prior to, simultaneously with, or after the spraying of the essentially high sudsing spray-dried detergent composition with the-intimate mixture of the a,w-dialkylamide alkane and the oily substance.

Experiment

In a model experiment a spray-dried detergent powder suitable for fabric washing having the formulation shown below was dissolved in demineralised water to form a solution containing 10 g/I of the formulation.
In two separate experiments 0.04 g/I ethylene distearamide and 0.16 g/I mineral oil were dispersed in the solution. Dispersion was achieved either by hand-shaking for 60 seconds or ultrasonically. In the first experiment the two components were added to the solution separately, whereas in the second experiment they were first intimately mixed and then dispersed.
The foam generated by each of these two solutions, as compared with a control solution not containing antifoam was then measured using a Ross-Miles dynamic foam meter at 300 ml/min flow rate. The results are shown in Table 1, from which it can be seen that it is only in the case where the ethylene distearamide is intimately mixed with mineral oil that effective foam control is obtained.
The invention is illustrated by the following example.

Example

This Example illustrates the manufacture of a conventional detergent powder where the antifoam mixture is added to the slurry before spray drying, and the manufacture of an otherwise identical detergent powder according to the invention, the antifoam mixture being sprayed on to the base powder after spray drying. The Example also compares the foam control of these two powders.
The following two detergent powders were accordingly produced by a process involving slurry making and counter-current spray-drying steps.
Two parts of the ethylene distearamide/wax mixture were sprayed onto spray-dried powder B, and then both powders were dry-dosed with 18.8 parts of sodium perborate.
The foam produced by each formulation was then assessed as described in the Experiment. The results are shown in Table 2.
The deactivation of the antifoam processed by the through-slurry route (Powder A) is evident, whereas the good retention of foam control of the powder sprayed with the intimate mixture of ethylene distearamide and was (Powder B) is characterised by the low foam heights recorded.

Claims

1. A process for the manufacture of low-sudsing detergent composition which comprises forming an essentially spray-dried detergent composition and adding a suds-suppressant to it by spraying, characterised in that the suds-suppressant comprising an intimate mixture of an oily or waxy substance and an a,w-dialkylamide alkane having the structure:

where n is the integer 1 or 2.

2. A process according to claim 1; in which the a,w-dialkylamide alkane is a,w-distearylamide methane.

3. A process according to claim 1, in which the α,ω-dialkylamide alkane is a,w-distearylamide ethane.

4. A process according to any one of the preceding claims, in which the oily or waxy substance comprises a mineral oil, a petroleum jelly, a wax or a mixture thereof.

5. A process according to any one of the preceding claims, in which the suds-suppressant is sprayed onto the spray-dried powder in an amount such it forms from 0.5 to 3.5% by weight of the composition.

6. A process according to any one of the preceding claims, in which the relative proportions by weight of the α,ω-dialkylamide alkane and the oily substance in the suds-suppressant are from 2.5:97.5 to 9:1.

7. A process according to claim 6, in which the relative proportions by weight are 5:95 to 1:3.

8. A process according to any one of the preceding claims, in which the suds-suppressant comprises a dispersing agent in the form of a nonionic surfactant.

9. A process according to claim 8, in which the relative proportions, by weight, of dispersing agent to suds-suppressant are from 0.2:99.8 to 3:1.