COMPOSITIONS CONTAINING NONIONIC SURFACTANTS AND A PROCESS FOR PRODUCING THEM

Abstract: Autoxidation during the spray-drying of detergent powders containing major proportions of nonionic surfactants can be reduced by using a copolymer as an antioxidant. The copolymer is formed from dicyclopentadiene and a mixture of 2- and 3-methyl phenols. It is particularly effective with powders containing nonionic surfactants of the alkoxylated alcohol type, for instance C₆-C₂₄ primary or secondary alcohols ethoxylated with from 3 to 25 moles of ethylene oxide per mole of alcohol. Preferred amounts of the copolymer are from 0.001 to 0.5% by weight based on the detergent composition.

Description: PROCESSING OF DETERGENT COMPOSITIONS CONTAINING NONIONIC SURFACTANTS This invention relates principally to detergent powders containing a nonionic surfactant as the major detergent active compound. It also relates to a process for preparation of such detergent powders. We have now filed a number of patent applications concerned with increasing the stability of detergent formulations during processing. Solutions to the problem have largely been concerned with addition to the detergent slurry of nitrogen-containing compounds such as alkanolamides, amines and quaternary ammonium salts. In practice a nitrogen compound of this sort helps to inhibit autoxidation which is the main problem which arises during processing, and also helps to inhibit any tendency to decomposition during storage after manufacture has been completed. US Patent No 3,403,107 discloses the use of antioxidants for inhibition of smoke formation during spraydrying of nonionic surfactants and more significantly discloses@a large number of phenolic antioxidants, including some which are substituted bis phenols. We have no discovered that one particular phenolic antioxidant which is not disclosed in the above US patent has an exceptional effect in inhibiting oxidation of detergent slurries containing nonionic surfactants. According to its broadest aspect, the invention provides a composition comprising a nonionic surfactant and a minor amount of a copolymer of cyclopentadiene sith a mixture of 2- and 3- methyl phenols as an antioxidant. In a narrower aspect, the invention provides a detergent composition comprising from 2 to 50 /ó by weight of a C6-C24 primary or secondary alcohol ethoxylated with from 3 to 25 moles of ethylene oxide per mole of alcohol and from 0.001 to 0,5 by weight of a copolymer of dicyclopentadiene with a mixture of 2- and 3- methyl phenols as an antioxidant. In a second aspect, the invention provides a process for the manufacture of a detergent powder lshich comprises forming an aqueous slurry comprising a C6-C24 primary or secondary alcohol ethoxylated with from 5 to 25 moles of ethylene oxide per mole of alcohol and a minor amount of a copolymer of dicyclopentadiene with admixture of 2- and 3methyl phenols and spray-drying it A copolymer of dicyclopentadiene with a mixture of 2- and 3- methyl phenols is sold by Lowi GmbH under the trade name "Lominox 22CP46". It is believed to have the general formula EMI2.1 In the remainder of the specification this antioxidant is referred to as "22CP46". We have discovered that this antioxidant has a combination of advantages which make it, so far as lie are aware, one of only two commercially available antioxidants suitable for use in detergent powders containing nonionic surfactants, the other one being 'Topanol CA' (registered Trade Mark) which is a hindered phenol, the use of which is described in DOLS 2 806 702. It is stable in hot alkaline media and does not give rise to colouration in an otherwise colourless composition. It is soluble in nonionic surfactants of the sort most commonly used in detergent compositions, that is those having hydrophobes derived from Cm,20 primary and secondary alcohols and hydrophilic components formed from 5 to 20 moles of ethylene oxide. This solubility makes it extremely easy to handle in a factory environment. It is very heat stable and has low volatility, so it neither decomposes to unwanted decomposition products nor volatilises during a spray-drying process. It is very effective as an antioxidant at low levels and over a wide range of temperatures. Finally it appears to be physiologically and environmentally acceptable, unlike many other antioxidants. We have examined a very large number of commercial antioxidants, but fe have had such an impressive combination of advantages as 22CP46. Most conventional food antioxidants have poor stability, are volatile or produce colourations in detergent powders, either during manufacture or subsequently during storage. Many of the newer, more exotic antioxidants are also extremely suspect physiologically. 22CP46 can be used either simply mixed with a nonionic surfactant, to inhibit oxidation in a storage tank, or it can be admixed with the surfactant shewn the crutcher slurry is formulated to inhibit oxidation during spray-drying and subsequently. 22CP46 is extremely effective at very low levels in the detergent powder. As little as 0.001 based on the weight of the final detergent ponder is effective, although 0.02 to 0.10% by weight is preferred. Obviously the minimum effective amount nill be used having regard to the cost of the material. 22CP46 is normally incorporated in the crutcher slurry in solution or dispersion but may also be-injected into a high pressure line carrying pressurised slurry to the spraying nozzles of a spray-drying tower, If nonionic surfactant is being supplied to the spraydrying tower in that way, then 22CP46 can be dissolved in the surfactant and injected at the same time. The amount of nonionic surfactant present in the detergent slurry will be sufficient to provide- from 2 to 50% by weight inthe final powder. All of the nonionic surfactant required in the spray-dried powder may be incorporated into the slurry or part of it may be incorporated by another method, such as by spraying onto the spray-dried powder, or by using a preformed adjunct. In the latter case the slurry will contain 2 to 1550, by weight of nonionic surfactant based on the final powder. The invention is applicable not only to detergent slurries and powders in which the surfactant is nonionic, but also to those containing mixtures of nonionic surfactants with other surface active species. Examples of these are synthetic anionic detergents, primary and secondary alkyl-sulphates, olefine sulphonates and alkyl benzene sulphonates, salts of fatty acids (soaps), cationic and zwitterionic surfactants. As has been intimated, the invention is particularly applicable to the spray-drying of powders containing nonionic surfactants of the alkoxylated alcohol type although other nonionic surfactants which give powders susceptible to autoxidation will also exhibit the imnrovement. The alcohols used can be primary or secondary alcohols containing straight or branched carbon chains The number of carbon atoms will generally be from 6 to about 24, preferably from about 8 to 18 and most preferably from about 11 to 16. These alcohols may be the so-called synthetic alcohols made by the well-knolsn Ziegler or Oxo processes, or the so-called "natural alcohols'1 made by hydrogenation of fatty acid derivatives, for example tallow alcohol. The alkoxylation reaction will be carried out by conventional means, generally using ethylene oxide or propylene oxide or both. The degree of ethoxylation can vary widely both from one hydrophobe to the other 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 lvill be applicable here. The choice of carbon chain length of the hydrophobe and the chain length of the hydrophobic 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-lipophilic balance (HLB). An approxi mate method of determining the HLB of alcohol ethoxylate is to use the expression HLB = Wt percentage of ethylene oxide 5 Nonionic surfactants which are suitable for use in heavy duty fabric washing powders generally having an HLB in the range 9 to 16, although HLB's outside this range are not excluded. An additional factor in the choice of nonionic surfactant is that the 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. 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 C1115 alcohols and Tergitols 45-S-?, 45-S-9, 45-S-12 and 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 and Shell Chemicals Inc as Dobanols and Neodols (Registered Trade Marks) respectively, 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¯, 45-12 and 45-15 which are ethoxylates of a mixture of C 14-15 alcohols. Ukanils (Trade Mark) hitch are a series of ethoxylates of Oxo alcohols containing about 25% of alpha methyl branched and about 10% of ethyl branched material (Acropols (Trade Mark) manufactured by Ugine Kuhlmann et Cie, especially Acropol 35-7, 35-9, 35-11 and 35-15 which are derived from a mixture of C13-Cl5 alcohols). 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 15 mixture of alcohols and ethoxylated to 7,9,11 and 15 units of ethylene oxide. Ethoxylates of primary Ziegler alcohols (Alfols (Trade Mark) derived from 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 containing about 60 p branched material sometimes called Lials (Trade Mark) produced from olefins manufactured by Liquichimica. Lutensols (Trade Mark), which are a series of ethoxylated alcohols sold by BASF, especially Lutensol A07 and Lutensol A08. Lastly, ethoxylates of natural alcohols, such as tallow alcohol can be used. The required HLB can be achieved not only by selecting the carbon chain length of the hydrophobe and the length of the ethyleneoxy chain in a single or substantially single material (because of the nature of their process of production, all nonionic surfactants hitch are spoken of as if they ere single substances are in fact mixtures). It can also be achieved by deliberately taking to "substances" of widely differing ELB's and mixing them. This approach is described in Netherlands patent application No 7 413 522 and in Netherlands patent application No 7 406 003. It is also possible to obtain the required HLS by "stripping" some chain lengths from a nonionic surfactant mixture as described in patent applications based on US S/No 453 462 and US patent 3 682 849. The detergency builders which may be used in the compositions of this invention may be any of the sequestrant or precipitant builders which have been suggested to replace phosphate builders, or they may be phosphate salts, or mixtures of any one of these, generally in amounts from 10 to 60% by eight in the case of phosphate builders and 10 to 35q by weight in the case of non-phosphate ones. Examples of detergency builders which may be used are ortho-, pyro- and tripolyphosphates; aluminosilicates; carbonates, especially the sodium carbonate/calcium carbonate combination; polyphosphonates such as ethanel-hydroxy-l,l-diphosphonate; amine carboxylates such as nitrilotriacetates and ethylene diamine tetra acetates; ether carboxylates such as oxydiacetates, oxydisuccinates, carboxymethyloxysuccinates and malonates; citrates; mellitates; and salts of polymeric carboxylic acids such as polymaleates, polyitaconates and polyacrylates. These salts will normally contain alkali metal or ammonium cations, preferably sodium. mixtures of sodium ortho- and tripolyphosphate are also suitable detergency builders, particularly mixtures in the range 10:1 to 1:5, preferably 5:1 to 1:1 tripolyphosphate to orthophosphate, in amounts of 10 to 60% by weight . Other conventional components of detergent compositions may be present in conventional amounts. Examples of these include powder flow aids such as finely divided silicas and aluminosilicates, antiredeposition agents such as sodium carboxymethylcellulose, oxygenreleasing bleaching agents such as sodium perborate and sodium percarbonate, per-acid bleach precursors such as tetraacetylethylenediamine, chlorine-releasing bleaching agents such as trichloroisocyanuric acid and alkali metal salts of dichloroisocyanuric acid, fabric softening agents such as clays of the smectite and illite types, antiashing aids, starches, slurry stabilisers such as copolyethylene maleic anhydride and copolyvinyimethylether maleic anhydride, usually in salt form, inorganic salts such as sodium silicates and sodium sulphate, and usually present in very minor amounts, fluorescent agents, perfumes, enzymes such as proteases and amylases, germicides and colourants. The detergent compositions usually have an alkaline pH, generally in the region of pH 9-11, which is achieved by-the presence of alkaline salts, especially sodium silicates such as the meta-, neutral or alkaline silicates (Na2O:SiO2 1:1 to 1:3.3), preferably at levels up to about 15% by weight. The invention will be illustrated by means of the following Examples. Example 1 In this Example the effectiveness of 22CP46 in inhibiting oxidation is demonstrated by a modification of the method of P L Bowes and A Cameron described in J.Appl.Chem. & Biotechnol. 1971. This method involves suspending a cubic, open-topped basket (side length 10 cm) containing the powder under test in an oven set to a given temperature. The powder has a thermocouple embedded in the centre of it, connected to a chart recorder. lffien spontaneous combustion sets in, a rapid rise in temperature occurs. The time taken for this rapid rise in temperature is recorded. Results can be presented either as the time taken to autoxidise at a given temperature (times greater than 24 hours for samples held at 150 C are considered good), or as the maximum temperature at which no oxidation occurs within 24 hours (temperature increments of 10 0C are normally used when ease of autoxidation is assessed in this way). The ponder formulations and the maximum temperatures at which no autoxidation occurs within 24 hours are shown belo-ri. Ingredient % by weight A B C D E F C12-15 primary alcohol 7EO ethoxylate 11.9 11.9 11.9 18.9 13.5 13.5 Tallow ethanolamide 2.2 2.2 2.2 2.2 2.0 2.0 Tallow soap 1.5 1.5 1.5 1.5 1.3 1.3 Alkaline sodium silicate (2:1 ratio) 14.8 14.8 14.8 14.8 13.3 13.3 Sodium tripolyphosphate 48.4 48.4 48.4 48.4 43.3 43.3 Sodium sulphate 5.4 5.4 5.4 5.4 11.8 11.8 22CP46 Nil 0.015 0.035 0.74 Nil 0.13 Moisture and minor ingredients to 100 to100 to100 to100 to100 to100 Maximum temperature at which autoxidation did not occur ( C) 130 150 160 160 130 200 The 22CP46 imparted no colouration to the spray-dried material in the spray-drying power exhaust gases, thus confirming its stability to both alkaline media and heat, and its low volatility. Example 2 This Example shows the heat stabilising effects of to further antioxidants. However, whereas incorporation of 22CP46 resulted in normal white powders, use of these antioxidants resulted in coloured powders, because of the instability of the antioxidants in alkaline media. Ingredient % by weight G H I C12-15 secondary alcohol 9EO ethoxylate 16.2 16.2 16.2 Coconut ethanolamide 2.2 2.2 2.2 Coconut soap 3.0 3.0 3.0 Alkaline sodium silicate 7.6 7.6 7.6 Sodium tripolyphosphate 54.8 54.8 54.8 Sodium toluene sulphonate 1.5 1.5 1.5 Gum Guaicum(a) 0.15 Nil Nil Butyl hydroxyanisole Nil 0.15 Nil Water and minor ingredients to 100 to 100 to 100 Time to autoxidation at 150 C (hours) 15 11 8 Colour of spray dried powder cream/ pink white yellow (a) Gum Guaicum is an antioxidant of the hindered phenol type used in foodstuffs.

Claims: CLAIMS: 1. A composition comprising a nonionic surfactant and a minor am@ant of a copolymer of cyclopentadiene with a mixture of 2- and 3-methyl phenols as an antioxidant. 2. A composition according to claim 1 in the form of a spray-dried detergent powder. 3. A composition according to claim 1 or claim 2 comprising from 2 to 50, % by weight of a C6-C24 primary or secondary alcohol ethoxylated with from 3 to 25 moles of ethylene oxide per mole of alcohol and from 0,001 to 0.5% by weight of a copolynier of dicyclo-pentadiene with a mixture of 2- and 3-methyl phenols as an antioxidant. 4. A composition according to any one of the preceding claims comprising from 0.02 to O.109o' by weight of the copolymer 5, A detergent composition according to any one of the preceding claims comprising from 10 to 60% by weight of a phosphate detergency builder. 6. A detergent composition according to any one of claims 2 to 5 comprising from 10 to 30% by weight of a nonphosphate detergency builder. 7. A composition comprising a nonionic surfactant and a minor amount of a copolymer of cyclopentadiene with a mixture of 2- and 3-methyl phenols, substantially as hereinbefore described in any one of the examples. 8. A process for the manufacture of a detergent powder which comprises forming an aqueous slurry comprising a C6-C24 primary or secondary alcohol ethoxylated with from 5 to 25 moles of ethylene oxide per mole of alcohol and from 0.001 to 0. 5 p by weight of a copolymer of dicyclopenta- diene with a mixture of 2- and 3-methyl phenols as an antioxidant, and spray-drying it, 9, A process as claimed in claim 8 wherein the amount of ethoxylated alcohol nonionic surfactant in the slurry is sufficient to provide from 2 to 50% by eight in the spray dried powder. 10. A process for the manufacture of a detergent powder comprising forming an aqueous slurry comprising a C6-C24 primary or secondary alcohol ethoxylated with from 3 to 25 moles of ethylene oxide and from 0.001 to 0.5% by weight of a copolymer of dicyclopentadiene vith a mixture of 2- and 3methyl phenols, substantially as hereinbefore described in any one of the examples.

Inventors: CURTIS, MICHAEL
Applicants: UNILEVER NV, UNILEVER PLC
Application year: 1980
Main classification: C11D1
IPC codes: C11D11, C11D1, C11D3