DE68920768T2 - Detergent composition. - Google Patents

Description

This invention relates to a detergent composition, in particular a detergent composition for washing fabrics.

Fabric washing compositions contain as an essential ingredient a surfactant system whose role is to assist in the removal of soil from the fabric and its suspension in the washing liquid. Suitable detergent-active surfactant materials fall into a number of classes including anionic, non-ionic and cationic materials. Products placed on the market contain materials selected from one or more of these classes.

The most commonly used anionic surfactant materials are the alkylbenzene sulfonates and these provide satisfactory results, especially at high temperatures. There has been a desire to find alternative anionic surfactants for use in those cases where alkylbenzene sulfonates are undesirable.

Among such alternative anionic surfactants are the fatty acid ester sulfonates (FAES) of the general formula

in which R¹ is an alkyl group derived from a fatty acid, usually from a natural source, R² is a short chain alkyl group, usually methyl and M is, for example, a is an alkali metal. For example, U.S. Patent 4,416,809 (Magari et al., assigned to Lion Corporation) describes a composition containing FAES, soap and the salt of a polycarboxylic acid. Exemplary FAES materials are those in which R¹ is derived from tallow and R² is methyl. Ethyl or propyl are also mentioned as possible substituents for R².

EP-A-207 642 describes surfactant formulations which are mixtures of an anionic surfactant which is either a fatty acyl ester sulfonate or an acyl isethionate and a non-ionic surfactant. The fatty acyl ester sulfonates defined are defined such that the residue of an esterifying alcohol contains from 1 to 5 carbon atoms. The non-ionic surfactants are stated to be various ethoxylated compounds containing from 2 to 25 ethylene oxide residues.

EP-A-231 891 describes concentrates of fatty acyl ester sulfonates containing 50 to 70% by weight of surfactant, where the surfactant is a mixture of fatty alkyl ester sulfonate and ethoxylated fatty alcohol. The fatty acyl ester sulfonate is preferably a methyl or ethyl ester, but esters of alcohols containing from 1 to 4 carbon atoms and esters of longer alcohols up to octanol are also mentioned. The ethoxylated fatty alcohols may be ethoxylated with an average of 3 to 15 ethylene oxide residues, and a preference is given for an average of 3 to 10 ethylene oxide residues.

However, it has been found that the performance of FAES materials in which R² is short chain alkyl is not satisfactory when the compositions also contain non-ionic surfactants with low HLB. Since the use of such non-ionic surfactants has been shown to result in a number of advantages including an overall activation in cleaning power (cf. GB 1 241 754 - Unilever), there is a desire to improve the performance of FAES materials in the presence of such non-ionic materials.

It has now surprisingly been found that this goal can be achieved by using materials in which R² is butyl or higher alkyl.

Therefore, according to the invention, there is provided a detergent composition containing a surfactant system, of which at least 50% by weight comprises:

(i) A fatty acid ester sulfonate, and

(ii) a non-ionic surfactant having an HLB value of less than 10.5, preferably less than 9.5,

wherein the fatty acid ester sulfonate has the general formula

in which R¹ and R², independently, are hydrocarbon groups having at least 4 carbon atoms, the sum of the carbon atoms in the radicals R¹ and R² being from 8 to 30 and M is a monovalent cationic species.

The fatty acid ester sulfonate salts of the above general formula can be prepared from fatty acids in a conventional manner. Desirable starting fatty acids are, for example, those derived from tallow, palm oil or coconut oil. It is therefore preferred that the R¹ radical contains from 12 to 18 carbon atoms. It can be completely or substantially saturated. The R² radical can have fewer carbon atoms than the R¹ radical. For example, the R² radical can have from 4 to 8 carbon atoms. In particular, it can be a butyl radical.

The sum of the carbon atoms in the radicals R¹ and R² will preferably be in the range of 12 to 24. It is also preferred that R¹ and R² are different, especially when the sum of the carbon atoms in the radicals R¹ and R² is 14 or more. A preferred FAES material is that in which R¹ is coconut alkyl and R² is butyl.

Mixtures of FAES materials as defined above could be used. Other FAES materials, such as the tallow methyl material, may also be included in smaller amounts, but there is no particular advantage in doing so.

It is preferred to use the water-soluble salts of these anionic To use surfactants, especially the alkali metal (sodium or potassium) salts thereof.

Suitable nonionic surfactants which can be used are the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkylphenols with alkylene oxides, particularly ethylene oxide, either alone or with propylene oxide. Specific nonionic detergent compounds are alkyl (C6-22) phenol-ethylene oxide condensates, the condensation products of aliphatic (C8-18) primary or secondary linear or branched alcohols with ethylene oxide, and products prepared by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine.

When alkylene oxide adducts of fatty materials are used as non-ionic surfactants, the number of alkylene oxide groups per molecule has a significant effect on the HLB value of the non-ionic surfactant. The chain length and nature of the fatty material is also influential, and consequently the preferred number of alkylene oxide groups per molecule depends on the nature and chain length of the fatty material.

It has been found that it is advantageous if the weight ratio between the anionic surfactant and the alkoxylated nonionic surfactant is between 4:1 and 1:4, more preferably between 3:1 and 1:2, since otherwise the advantages of the invention cannot be achieved.

Preferred compositions according to the invention include the surfactant system in an amount of from 2 to 50 weight percent, such as from 4 to 30 weight percent of the composition.

The surfactant system may contain other surfactant materials besides the specified sulfonate and non-ionic materials. These other surfactant materials may be selected from other anionic detergent-active materials, zwitterionic or amphoteric detergent-active materials, or mixtures thereof.

Any such additional surfactant materials will be present in an amount not exceeding 50%, preferably not exceeding 40% of the total amount of surfactant in the composition, and should not exceed 5% of the total composition.

The other anionic detergent-active materials may be the usual water-soluble alkali metal salts of organic sulfates and sulfonates, having alkyl radicals containing from 8 to 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are sodium and potassium alkyl sulfates, especially those obtained by sulfating higher (C8-18) alcohols prepared, for example, from tallow or coconut oil, sodium and potassium alkyl (C9-20) benzene sulfonates, especially linear secondary sodium alkyl (C10-15) benzene sulfonates; sodium alkyl glyceryl ether sulfates, especially those ethers of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived from petroleum; sodium coconut oil fatty monoglyceride sulfates and sulfonates; sodium and potassium salts of higher sulfuric acid esters. (C8-18) fatty alcohol alkylene oxide, especially ethylene oxide reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralized with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyltaurine; alkane monosulfonates such as those derived by reacting alpha-olefins (C8-20) with sodium bisulfite, and those derived from reacting paraffins with SO2 and Cl2 followed by hydrolysis with a base to produce a random sulfate.

The compositions of the invention may contain a detergency builder material, this may be any material capable of reducing the content of free calcium ions in the washing liquid and which will preferably provide the compositions with other advantageous properties such as the formation of an alkaline pH and the suspension of dirt removed from the fabric.

Examples of phosphorus-containing inorganic detergent builders include, when present, the water-soluble salts, particularly alkali metal pyrophosphates, orthophosphates, polyphosphates and phosphonates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates.

Examples of non-phosphorus-containing inorganic detergency builders include, when present, water-soluble alkali metal carbonates, bicarbonates, silicates, and crystalline and amorphous aluminosilicates. Specific examples include sodium carbonate (with or without calcite crystals), potassium carbonate (with or without calcite crystals), sodium and potassium bicarbonates, and silicates.

Examples of organic detergency builders include, when present, the alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl carboxylates and polyhydroxysulfonates. Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid, benzenepolycarboxylic acids and citric acid.

It is preferred that the compositions according to the invention are alkaline, that is to say that the pH at the concentration of 1 g/l in distilled water at 25°C should be at least 8, preferably at least 10. For this purpose, the compositions may contain a water-soluble alkali salt. This salt may be a detergency builder or an alkaline non-builder material.

Apart from the components already mentioned, a number of optional components may also be present.

Examples of other ingredients that may be included in the composition include fabric softening agents such as fatty amines, fabric softening clays, foam improvers such as alkanolamides, particularly the monoethanolamides, derived from palm kernel fatty acids and coconut fatty acids, foam suppressors, oxygen releasing bleaches such as sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine releasing bleaches such as trichloroisocyanuric acid, inorganic salts such as sodium sulfate and, normally present in very small amounts, fluorescers, perfumes including deodorant perfumes, enzymes such as proteases, cellulases, amylases and lipase, germicides and dyes.

The detergent compositions according to the invention can be prepared by a number of different processes according to their physical form. In the case of granular products they can be prepared by dry blending or coagglomeration. A preferred physical form is a granule containing a detergent builder salt and this is particularly suitably prepared by spray drying at least a portion of the composition. In this process a slurry is prepared containing the heat insensitive components of the composition such as the surfactant system, the builder material and the filler salt. The slurry is spray dried to form a base powder granule which may be mixed with any solid heat sensitive ingredients, such ingredients including bleaches and enzymes. The specified non-ionic surfactants may be liquefied by melting or dissolving in solvent and sprayed onto the base powder granules, rather than including them in the slurry for spray drying. The invention will now be described in more detail in the following non-limiting examples.

Examples 1 to 6

Washing liquids were prepared in water having a hardness of 25º FH (equivalent to a free calcium ion concentration of 2.5 x 10⊃min;³ molar). The washing liquid contained the equivalent of 6 g/l of a composition containing (based on weight):

Specified anionic surfactant 9%

Specified non-ionic surfactant 4%

Sodium tripolyphosphate 23%

Sodium carbonate 6%

Sodium alkali silicate 5.5%

Sodium sulfate 30.8%

Sodium chloride 2.93%

Water Rest

The sodium chloride was included as equivalent in ionic strength to 5% sodium perborate monohydrate, which is present in practice. The bleach was omitted from these tests to avoid confusion between detergency and bleaching effect in the interpretation of the results.

The wash liquids were used to wash a fabric load at a liquid to fabric ratio of 50:1. The fabric load contained a number of polyester monitors to which a quantity of C14 labelled triolein had previously been applied. Measurement of the level of labelled triolein after washing provided an indication of the degree of detergency, i.e. soil removal, obtained using standard radiotracer procedures.

The washing time was 20 minutes with agitation at 70 rpm. The washing was isothermal at 40ºC.

In each case, the nonionic surfactant was either SYNPERONIC A7 (ex ICI), which is primarily a C13/C15 alcohol ethoxylated with an average of 7 moles ethylene oxide per molecule and an HLB of 11.7, or a 1:3 weight percent mixture thereof with SYNPERONIC A3, which is a similar material containing an average of 3 moles ethylene oxide per molecule, the mixture having an HLB of 9.0. "Synperonic" is a registered trademark.

The anionic surfactants used were:

CM: coconut methyl FAES;

TEXIN ES 68: A tallow methyl FAES from Henkel;

LB: C12-alkylbutyl-FAES.

The results obtained were as follows: Example No. Anionic Non-ionic % Soil removal

These results show that in the presence of the higher HLB nonionic material (Examples 1 to 3) there is very little difference between the anionic surfactants tested. However, in the presence of the lower HLB nonionic blend (A7/A3) there is a significant preference for the C12-butyl FAES over the others tested.

Claims (6)

1. Detergent composition containing a surfactant system, characterized in that such a surfactant system comprises at least 50% by weight of (i) a fatty acid ester sulfonate, and (ii) a non-ionic surfactant having an HLB value of less than 10.5, wherein the fatty acid ester sulfonate has the general formula in which R¹ and R² are independently hydrocarbon groups having at least 4 carbon atoms, the sum of the carbon atoms in the radicals R¹ and R² is in the range from 8 to 30, and M is a monovalent cationic species. 2. Detergent composition according to claim 1, wherein the sum of the carbon atoms in the radicals R¹ and R² is in the range of 12 to 24 carbon atoms. 3. A detergent composition according to claim 1 or claim 2, wherein the group R¹ is a hydrocarbon group containing from 12 to 18 carbon atoms. 4. A detergent composition according to claim 1, wherein the fatty acid ester sulfonate is an alkali metal salt of the sulfonate of the butyl ester of coconut fatty acid. 5. A detergent composition according to any one of the preceding claims, wherein the nonionic surfactant has an HLB value of 9.5 or below. 6. A detergent composition according to any one of the preceding claims, wherein the surfactant system constitutes from 2 to 50 percent by weight of the total composition.