GB1595293A - Process for preparing detergent powders containing nonionic surfactants - Google Patents

Description

(54) PROCESS FOR PREPARING DETERGENT POWDERS CONTAINING NONIONIC SURFACTANTS (71) We, UNILEVER LIMITED, a company organised under the laws of Great Britain, of Unilever House, Blackfriars, London E.C.4, England, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a fabric washing powder containing one or more nonionic surfactants as the major detergent active species.

It is now generally accepted in the industry that nonionic surfactants are capable of imparting to fabric washing powders a definite superiority in detergency, especially in the area of oily soil removal from modern fibres. However, the use of nonionic surfactants has not really become widespread, largely because of processing problems. One of the processing problems which arises is that crutcher slurries containing high levels of nonionic surfactants tend to produce spray-dried powders of rather higher bulk density than is the case with conventional soap or "ternary mix" powders. We have found it possible to combat this tendency to increased density by incorporating a small amount of soap into the formulation. This has proved satisfactory from the processing point of view but it has disadvantages as regards product performance.Even small amounts of soap have been found to depress the detergency of the nonionic surfactant to a significant extent.

We have now discovered that by selection of soaps of suitable chain length we can avoid the depression in detergency yet retain the facility for obtaining low bulk density powders.

Accordingly, the present invention provides a spray-dried fabric washing detergent powder comprising from 5 to 25%, preferably 5 to 15% by weight of a nonionic surfactant as the major detergent active species and from 0.5 to 5%, preferably 0.5 to 3%, by weight of a sodium soap of a fatty acid having 10 or fewer carbon atoms.

An example of a sodium soap containing 10 or fewer carbon atoms is a soap of a mixture of fatty acids containing 65-85% of a Cg saturated acid and 15-25% of a Clo saturated acid.

Such a fatty acid mixture can be obtained from Price's Chemicals Ltd. These mixtures are manufactured from a blend of tallow, coconut oil and acid oils derived largely from palm kernel. The blend is passed through a fat-splitting column and the short chain length acids specified for use in this invention are obtained by taking the uppermost 1l/2% from the column.

As stated above, the level of fatty acid soap used should be 0.5 to 5%, preferably 0.5 to 3% based on the spray-dried powder. Of course if the powder is subsequently dosed with other detergent components in large quantities then these percentages will be correspondingly reduced when expressed as a proportion of the final product. We prefer for reasons of economy, and also because too great a loading of organic materials in the crutcher slurry can cause problems, to use as low a level of soap as will suffice for reducing the bulk density of the powder to 0.25 to 0.40 g/cm3.

The nonionic surfactant for use in the compositions of the invention will normally be an alkoxylated long chain alcohol, although this is not essential. Nevertheless we have found these nonionic surfactants most suitable for use in fabric washing powders, having regard to the often conflicting requirements of good detergency, safe biological properties and ease of processing.

The alcohols from which the nonionic surfactants can be prepared can be primary or secondary alcohols containing straight or branched carbon chains. The number of carbon atoms will generally be from 7 to 24, preferably from 8 to 18 and most preferably from 12 to 16. These alcohols may be the so-called synthetic alcohols made by the well known Ziegler or Oxo processes, or the so-called "natural alcohols".

The alkoxylation reaction will be carried out by conventional means, generally using ethylene oxide or propylene oxide. The degree of ethoxylation can vary widely both from one hydrophobe to another and even when using a single hydrophobe. Thus ethylene oxide chains containing as few as 1 and more than 20 ethylene oxide units are quite often found in nonionic surfactants and will be applicable here.

The choice of carbon chain length of the hydrophobe and the chain length of the hydrophilic alkoxy chain is largely determined by the detergent properties required of the molecule. The relationship between the chain length of the hydrophobic part of the molecule and that of the hydrophilic part can be expressed numerically as the hydrophilic balance (HLB). An approximate way of determining the HLB is to use the expression.

Wt. Wt. percengate of ethylene oxide HLB = 5 Nonionic surfactants which are suitable for use in heavy duty fabric washing powders generally have an HLB in the range up to 13, although HLBs outside this range are not excluded.

An additional factor in the choice of nonionic surfactant is that alcohols containing both short carbon and short ethoxylate chain lengths are relatively low boiling and can volatilise under the conditions prevailing in a spray drying tower.

Hence alcohols containing less than 8 carbon atoms will not normally be chosen unless their ethoxy chains contain at least 8 ethylene oxide units.

Preferred alcohol ethoxylates for use in this invention are derived from the following series.

Tergitols (Trade Mark) which are a series of ethoxylates of secondary alcohols sold by the Union Carbide Corporation, especially Tergitol 15-S-7, 15-S-9, 15-S-12 and 15-S-15 which are ethoxylates of a mixture of Cl 1-15 alcohols and Tergitols 45-S-7, 45-S-15 which are ethoxylates of a mixture of C14 and C15 alcohols, the degree of ethoxylation being shown by the postscript.

Ethoxylates of primary alcohols made by the Oxo process and containing about 20% of alpha branched material sold by Shell Chemicals Ltd., Dobanols (Trade Mark) and Shell Chemicals Inc. Neodols (Trade Mark), especially Dobanol and Neodol 25-7, 25-9, 25-12 and 25-15 which are ethoxylates of a mixture of C12-C15 alcohols and Dobanol 45-7, 45-9, 25-12 and 25-15 which are ethoxylates of a mixture of C14-C15 alcohols.

Ukanils (Trade Mark) which are a series of ethoxylates of Oxo alcohols containing about 40% of alpha alkyl branched material manufactured by ethoxylation of, for example, Acropols (Trade Mark) especially Acropol 35 which is a C13-C15 alcohol mixture.

Synperonics (Trade Mark), a series of ethoxylates of alcohols containing 45-55% of alkyl branching, mostly methyl branching, sold by Imperial Chemical Industries Limited, especially those based on a C13-C15 mixture of alcohols and ethoxylated to 7, 9, 11 and 15 units of ethylene oxide.

Alfols (Trade Mark) which are ethoxylates of primary Ziegler alcohols derived by oxidative polymerisation of ethylene, manufactured by Conoco-Condea, especially Alfol 12/14-7, 12/14-9, 12/14-12, 12/14-15 and Alfol 14/12-7, 14/12-9, 14/12-12, 14/12-15 which are ethoxylates of mixtures of C12 and C14 alcohols.

Ethoxylates of primary Oxo alcohols about 50% branched, mainly a methyl sometimes called Lials (Trade Mark) produced from olefins manufactured by Liquidchemica.

Lutensols (Trade Mark) which are a series of C13-C15 alcohol ethoxylates prepared by the "Oxo" process from an olefin produced by the polymerisation of ethylene, manufactured by Badische Anilin und Soda Fabrik GmbH, especially Lutensol AO8 and 12.

The required HLB can be achieved not only by selecting the carbon chain length of the hydrophobe and the length of the alkyleneoxy chain in a single or substantially single material (because of the nature of their process of production, all nonionic surfactants which are spoken of as if they were single substances are in fact mixtures). It can also be achieved by deliberately taking two "nonionic substances" of widely differing HLBs and mixing them. It is also possible to obtain the required HLB by "stripping" some chain lengths from a nonionic surfactant mixture.

In addition the compositions of the invention can and normally will contain detergency builders in an amount up to 75% by weight of the spray-dried powder, preferably 10-60% and most preferably 30-60%. Any of the builders which have been suggested in the art may be used, for example the water soluble salts of ortho-, pyro- and tripolyphosphates, carbonates, bicarbonates and silicates, especially the sodium salts. The combination of sodium tripolyphosphate with alkaline sodium silicate, that is sodium silicate having an Na2O : SiO2 ratio in the range 1:1.6 to 1:2.0 has been found especially useful, although combinations with silicates having different Na2O : SiO2 ratios are not excluded.

The builders which have been suggested in responses to pressure to reduce the phosphorus content of detergents are also suitable for use with the process of this invention.

For example the salts, especially sodium salts of ethylene diamine tetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, citric acid, oxydiacetic acid, alkyl succinic acid, polyacrylic acid, hydrofuran tetracarboxylic acid, alkylaryl succinic and malonic acids, dipicolinic acid, alkane disulphonic acid, sulphosuccinic acid, and alkyl phthalic acid are all suitable. Other builder materials which can be used include oxidised polysaccharides, especially oxidised starch carboxymethyloxysuccinates and their hydrates and analogues, sulphonated fatty acid salts, "seed" builders such as the carbonate/calcite combination and aluminosilicates.

Other components of detergent compositions can be added to the slurry or post-dosed into the spray-dried base powder according to their known suitability for undergoing a spray-drying process. Examples of such components are oxidising bleaches such as sodium perborate and percarbonate optionally with bleach precursors such as tetra acetyl ethylene diamine, and tetra acetyl glycoluril, suds suppressors such as silicone oils, alkyl phosphates and micro-crystalline waxes, soil suspending agents such as sodium carboxymethyl cellulose, cellulose ethers and copolymers of maleic anhydride with ethylene or methyl vinyl ether, enzymes such as those sold under the trade names "Alcalase", and "Esperase" (SP72) by Novo Industries A/S, Denmark, fluorescers, and alkyl ethanolamides such as coconut monoethanolamide.

These conventional and optional components of the detergent compositions can be present together in an amount of from 15 to 50% by weight of the finished compositions when an oxidising bleach is present or at substantially greater levels in the absence of such bleach.

The invention will be further described with reference to the following Examples.

EXAMPLE 1 An aqueous detergent solution was prepared containing the following components in the stated concentrations: Concentration (gmsllitre) Synperonic 7, (registered Trade Mark) a Cm22 15 "Oxo" alcohol ethoxylate containing an average of 7 moles of ethylene oxide, supplied by ICI Ltd 0.65 Sodium tripolyphosphate 1.7 Alkaline sodium silicate (Na2O:SiO2,2: 1) 0.5 Sodium carbonate 0.85 Tallow monoethanolamide (see Tables) Soap (see Tables) The solution (containing zero or 0.065 gms/litre of the required soap) was used to wash standard Crimplene (registered Trade Mark) test cloths soiled with a standard, synthetic sebum and particulate soil in a Terg-O-Tometer (registered Trade Mark).Washing conditions were as follows: Hardness of water 0 & 26"H (see Table) Temperature 50"C Agitation 50 rpm Wash time 5 minutes Reflectance measurements were made on the Elrepho (registered Trade Mark) reflectance spectrophotometer at a wavelength of 460 nm. The differences between soiled and washed reflectances (A R values) are quoted in these examples.

Table 1 (26"H, 0% tallow monoethanolamide) % by weight of soap present Short chain length soaps* 0 0 100 Tallow soaps 0 100 0 Reflectance (A R) 27.1 23.5 28.9 Table 2 (26"H, 0.2% tallow monoethanolamide) % by weight of soap present Short chain length soaps* 0 0 100 Tallow soaps 0 100 0 Reflectance (A R) 29 24 29.0 EXAMPLE 2 The experiment in Example 1 was repeated using woven polyester crepe test cloths.The results were as follows: Table 3 (26"H, 0% tallow monoethanolamide) % by weight of soap present Short chain length soaps* 0 0 100 Tallow soaps 0 100 0 Reflectance (A R) 25.8 21.6 25.8 Table 4 (0 H, 0.2% tallow ethanolamide) % by weight of soap present Short chain length soaps 0 0 100 Tallow soaps 0 100 0 Reflectance (h R) 24.5 22.2 24.3 * Short length soaps are the mixtures described on page 3.

The above experiments show that the use of soaps in accordance with the invention avoids the deleterious effects of tallow soaps on detergency of a nonionic based detergent formulation.

The following example demonstrates that slurries for detergent formulations based on nonionic surfactants can be spray-dried to bulk densities having acceptably low values when a short chain length soap is included in the slurry.

EXAMPLE 3 Three base-powder fabric washing detergent formulations were prepared.

Formulations (parts by weight) A B C Synperonic 7 10.2 8.0 10.2 Tallow soap Nil Nil 1.0 Short chain length soap Nil 1.0 Nil Tallow ethanolamide 1.5 1.5 1.5 Sodium tripolyphosphate 32.6 32.6 32.6 Sodium sulphate 10.15 12.35 9.15 Alkaline sodium silicate 10.0 10.0 10.0 Minor ingredients 1.4 1.4 1.4 Water 9.5 9.5 9.5 75.35 75.35 75.35 The powders were produced by preparing a slurry of all the ingredients of the formulation, other than the nonionic surfactant, and spray-drying it in a counter-current spray-drying tower. The nonionic surfactant was injected into the high pressure line bearing the slurry to the spraying nozzles in order to avoid stability problems in the slurry crutcher.

The slurry was aerated prior to spray-drying as shown in Table 5.

The spray-drying conditions were: Slurry moisture content 46% Slurry temperature 80% Slurry pressure 800 psi Tower inlet temperature 305"C Tower outlet temperature 100"C After spray-drying the bulk density of the powder was measured and the results are shown in Table 5.

Table 5 Bulk Density (kgll) Aeration Rate (Nllkg) Formulation A Formulation B Formulation C 0 0.455 0.445 0.440 3 0.395 0.345 0.283 6 0.395 0.285 0.265 It can be seen that in the absence of aeration the bulk densities of the powder formulations are at a relatively high level, and that in the case of Formulation A, which does not contain soap, no significant depression is obtained on aeration. In the case of Formulations B and C however, a significant and similar depression is obtained, indicating that the effectiveness of short chain length soap in depressing bulk density is equivalent to that of tallow soap.

Reference is directed in pursuance of Section 9, subsection (1) of the Patents Act 1949 to patent Nos 1,232,009 and 1,506,392.

WHAT WE CLAIM IS: 1. A spray-dried fabric washing detergent powder comprising from 5 to 25% by weight of a nonionic surfactant as the major detergent active species and from 0.5 to 5% by weight of a sodium soap of a fatty acid having 10 or fewer carbon atoms.

2. A spray-dried fabric washing detergent powder according to claim 1, comprising from 5 to 15% by weight of the nonionic surfactant.

3. A spray-dried fabric washing detergent powder according to claim 1 or claim 2, comprising from 0.5 to 3% by weight of the sodium soap.

4. A spray-dried fabric washing detergent powder according to any one of the preceding claims, wherein the sodium soap is derived from a mixture containing 65-85% by weight of a C8 saturated fatty acid and 15-25% of a C10 unsaturated fatty acid.

5. A spray-dried fabric washing detergent powder according to any one of the preceding

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. EXAMPLE 3 Three base-powder fabric washing detergent formulations were prepared. Formulations (parts by weight) A B C Synperonic 7 10.2 8.0 10.2 Tallow soap Nil Nil 1.0 Short chain length soap Nil 1.0 Nil Tallow ethanolamide 1.5 1.5 1.5 Sodium tripolyphosphate 32.6 32.6 32.6 Sodium sulphate 10.15 12.35 9.15 Alkaline sodium silicate 10.0 10.0 10.0 Minor ingredients 1.4 1.4 1.4 Water 9.5 9.5 9.5 75.35 75.35 75.35 The powders were produced by preparing a slurry of all the ingredients of the formulation, other than the nonionic surfactant, and spray-drying it in a counter-current spray-drying tower. The nonionic surfactant was injected into the high pressure line bearing the slurry to the spraying nozzles in order to avoid stability problems in the slurry crutcher. The slurry was aerated prior to spray-drying as shown in Table 5. The spray-drying conditions were: Slurry moisture content 46% Slurry temperature 80% Slurry pressure 800 psi Tower inlet temperature 305"C Tower outlet temperature 100"C After spray-drying the bulk density of the powder was measured and the results are shown in Table 5. Table 5 Bulk Density (kgll) Aeration Rate (Nllkg) Formulation A Formulation B Formulation C 0 0.455 0.445 0.440 3 0.395 0.345 0.283 6 0.395 0.285 0.265 It can be seen that in the absence of aeration the bulk densities of the powder formulations are at a relatively high level, and that in the case of Formulation A, which does not contain soap, no significant depression is obtained on aeration. In the case of Formulations B and C however, a significant and similar depression is obtained, indicating that the effectiveness of short chain length soap in depressing bulk density is equivalent to that of tallow soap. Reference is directed in pursuance of Section 9, subsection (1) of the Patents Act 1949 to patent Nos 1,232,009 and 1,506,392. WHAT WE CLAIM IS:

1. A spray-dried fabric washing detergent powder comprising from 5 to 25% by weight of a nonionic surfactant as the major detergent active species and from 0.5 to 5% by weight of a sodium soap of a fatty acid having 10 or fewer carbon atoms.

2. A spray-dried fabric washing detergent powder according to claim 1, comprising from 5 to 15% by weight of the nonionic surfactant.

3. A spray-dried fabric washing detergent powder according to claim 1 or claim 2, comprising from 0.5 to 3% by weight of the sodium soap.

4. A spray-dried fabric washing detergent powder according to any one of the preceding claims, wherein the sodium soap is derived from a mixture containing 65-85% by weight of a C8 saturated fatty acid and 15-25% of a C10 unsaturated fatty acid.

5. A spray-dried fabric washing detergent powder according to any one of the preceding

claims, having a bulk density of from 0.25 to 0.40 gm/cm'.

6. A spray-dried fabric washing detergent powder according to any one of the preceding claims, wherein the nonionic surfactant comprises a C8-C18 primary or secondary alcohol ethoxylated with from 1 to 20 moles of ethylene oxide per mole of alcohol.

7. A spray-dried fabric washing detergent powder according to any one of the preceding claims, wherein the nonionic surfactant has a hydrophilic-lipophilic balance of up to 13.

8. A spray-dried fabric washing detergent powder comprising a sodium soap of a fatty acid having 10 or fewer carbon atoms substantially as hereinbefore described in either of Examples 1 or 3.