GB2236538A - Detergent compositions - Google Patents

Abstract

A detergent composition including a surfactant system the major proportion of which consists of: i) an anionic surfactant material which is a) an internal olefin sulphonate derived from an internal olefine @ having the general formula: R<1>-CH = CH-R<2> (I) of b) a vinylidene sulphonate derived from a vinylidene having the general formula: <IMAGE> or c) a mixture thereof, R<1> and R<2> being alkyl groups which are the same or different and have 10 to 16 carbon atoms in total; and ii) a nonionic surfactant material having an HLB value of not more than 10.5, the weight ratio of (i) to (ii) lying between 9:1 and 1:9.

Description

DETERGENT COMPOSITIONS This invention relates to detergent compositions, particularly but not exclusively to detergent compositions for cleaning fabrics.

Detergent compositions generally comprise a number of ingredients, including a detergent active surfactant material to assist the removal of soil from the materials to be cleaned and the suspension of the removed soil in the wash liquor. Notable applications of detergent compositions are to clean fabrics usually by washing portable fabric items in a bowl or in a washing machine, to clean hard surfaces such as glass, glaze surfaces, plastics, metals and enamels and to clean soft furnishings such as carpets.

A number of classes of materials have been used as detergent active materials, including anionic and nonionic materials.

The most widely used anionic surfactant materials are the alkyl benzene sulphonates. There has been a desire to find alternative anionic surfactant materials for use in circumstances when alkyl benzene sulphonates are undesirable, but frequently the performance of other anionic surfactant materials is unsatisfactory.

Known anionic surfactant materials which are potentially available as alternatives include: a) internal olefin sulphonates which are olefin sulphonates derived from olefins having the general formula: R1 - CH = CH - R2 b) vinylidene sulphonates which are olefin sulphonates derived from vinylidenes having the general formula:

In both of the above formulae R1 and R2 are alkyl groups but are not hydrogen.

We have now discovered that the performance of selected internal olefin sulphonates and vinylidene sulphonates can be * proved Dy the additional use of certain nonionic surfactant materials. Thus, according to the present invention there is provided a detergent composition for washing fabrics, the composition including a surfactant system the major proportion of which consists of: i) internal olefin sulphonate derived from internal olefin of the aaX se general formula (I) or vinylidene sulphonate derived from vinylidene of the above general formula (11) or a mixture thereof, in which sulphonates R1 and R2 may be the same or different but total 10 to 16 carbon atoms; and ii) a nonionic surfactant material having an HLB value of not more than 10.5.

The weight ratio of (i) to (ii) lying in the range from 9:1 to 1:9, preferably 4:1 to 1:4.

The usual method of preparation of internal olefin sulphonate or vinylidene sulphonate is by sulphonation of the appropriate internal olefin or vinylidene with sulphur trioxide, followed by neutralisation and hydrolysis of the reaction product.

It is desirable to use the water-soluble salts of these sulphonates, especially the alkali metal (sodium or potassium) salts thereof. Ammonium or alkanolammonium salts may also be used.

Since R1 and R2 total 10 to 16 carbon atoms, the total number of carbon atoms in the internal olefin or vinylidene is 12 to 18. In particular R1 and R2 may total at least 12 carbon atoms.

Internal olefins and their derivatives have different properties to alpha olefins and their corresponding derivatives although internal olefin sulphonates which distinguishes them from alpha olefin sulphonates is that internal olefin sulphonates have the olefinic bond randomly distributed in the chain. This means that over half of an internal olefin of formula quoted above will have R1 and R2 groups with at least four carbon atoms in each of these groups. This may also be true of the R1 and R2 groups of a vinylidene olefin sulphonate.

It is preferred that at least three quarters of the internal olefin or vinylidene has R1 and R2 groups with at least 4 carbon atoms in each.

Another way to express the distinguishing characteristic of an internal olefin sulphonate is that the majority of its molecules have the olefin bond between the third and fourth carbon atoms or even further from the ends of the carbon chain.

The content of any a-olefin sulphonate present with internal olefin sulphonate is typically not more than 20%, preferably less than 10% or even 5% of the total quantity of olefin sulphonate.

A preferred category of nonionic surfactant materials is the alkoxylated nonionics. In particular, preferred nonionic surfactants have a hydrophobic portion with a continuous carbon chain of more than eight carbon atoms which may be aliphatic or alkylaromatic and a hydrophilic portion consisting of one or more ethyleneoxy and/or glycerol residzles and terminating in at least one hydroxyl group on a said residue. Particularly preferred are ethoxylated nonionic surfactants which are the reaction products of ethylene oxide and compounds having a said hydrophobic group and a reactive hydrogen atom, for example aliphatic alcohols, acids, amides or alkyl phenols.

Snecific ethoxylated nonionic surfactant compounds are alkyl (C6 -C22) phenol-ethylene oxide condensates, the condensation products of aliphatic (C8-C18) primary or secondary linear or branched alcohols with ethylene oxide.

Ethylene oxide adducts of fatty materials are preferably used as the nonionic surfactants. The number of ethylene oxide groups per molecule has a considerable effect upon the HLB of the nonionic surfactant. The chain length and nature of the fatty material is also influential, and thus the preferred number of ethylene oxide groups per molecule depends tenon the nature and chain 'ength of the fatty material.

As indicated above, the nonionic surfactant has an HLB value not above 10.5. It is preferred that the nonionic surfactant has an HLB value below 10, preferably below 9.

It is well known that ethoxylated nonionic surfactants are mixtures of molecules with varying numbers of ethylene oxide groups including some unethoxylated material.

For this invention it is advantageous to use surfactants which have been purified to enhance the proportion of molecules which, if present as pure compound, would have the desired HLB value. This purification may consist of removing unethoxylated material giving a socalled "stripped nonionic" or purifying further to give a narrow distribution of the numbers of ethylene oxide groups, a so-called "peaked nonionic . These purified materials are commercially available.

Besides ethoxylated nonionic surfactants, other nonionic surfactants which can be used include fatty alkyl monoethers of glycerol and fatty amide monoethanolamides.

Preferred compositions according to the invention include from 1% to 50%, such as from 2% to 35% by weight of the surfactant system.

The surfactant system may include other surfactant materials in addition to the specified sulphonate and nonionic materials. These other surfactant materials may be selected from other anionic surfactant materials, zwitterionic or amphoteric surfactant materials or mixtures thereof.

Any such further surfactant materials should be present at a level which is no more than a minor amount of the total amount of surfactant in the composition.

It is desirable that the eventual wash liquor should contain electrolyte to yield an ionic strength of at least 5 x 10-'. There may well be enough electrolyte to give an ionic strength of at least 2 x 10-2 moles/litre.

Suitably, electrolyte is present in the detergent composition to yield such an ionic strength in the wash liquor when the composition is used. The concentration of surfaces @ in te wash liquor is likely to be from 0.05 to 2 g/litre preferably 0.1 to 1.5 g/litre.

Ionic strength is related to concentration but takes account of the numbers of ions in a molecule and multiple charged ions.

Ionic strength is calculated from the molarity .(m) of e-h ionic species present ir solution and the charge (z) carried by each ionic species. Ionic strength (I) is one half the summation of m.z2 for all ionic species present i.e.

I = S m.z2 For a salt whose ions are both univalent, ionic strength is the same as the molar concentration. This is not so where more than two ions or multiple charges are involved. For instance a 1 molar solution of sodium carbonate contains 2 moles/litre of sodium ions and 1 mole/litre t carbonate ions carrying a double charge.

Ionic strength is given by: I = 4 (2(12) + 1 x (22)) = 3 moles/litre A description of ionic strength is given in "Physical Chemistry" by Walter J. Moore, 4th Ed. 1963. It may be the case that both ionic strength and electrolyte concentration will reach 5 x 10- 3 moles/litre, or the preferred level of at least 0.02 moles/litre. It is not generally practical for electrolyte concentration to exceed 0.5 molar.

The level of electrolyte in a wash liquor is a parameter which, in practice, is determined by the level of water-soluble salts in the detergent composition and the dosage for the composition. Detergent compositions are generally used in amounts greater than 1 gram/litre, usually in the range from 4 g/litre to 10 g/litre. A detergent composition to provide the required ionic strength when used at such a dosage will generally contain at least 5% by weight of water-soluble salts. There may well be sufficient to yield an ionic strength of at least 0.1 moles/litre if usage of the composition is 10 g/litre.

Water-soluble salts which may be present in a detergent composition include water-soluble detergency builder materials. If the compositions of the invention contain a detergency builder material, this may be any material capable of reducing the level of free calcium ions in the wash liquor and will preferably provide the compositions with other beneficial properties such as the generation of an alkaline pH and the suspension of soil removed from the fabric.

It is conventional that a detergent composition which contains detergency builder, whether or not that builder is itself a water-soluble salt, will contain from 5 or 10 to 90% or 95% by weight of water-soluble salts and may well contain 30% to 80% of water-soluble salts. When detergency builder is present, whether or not it is watersoluble, it will generally be included in an amount from 5 or 10 to 60% by weight, preferably 20 to 50% by weight. One form of this invention is a composition containing 10 to 60% of insoluble detergency builder and 5 to 50% of water s=uble srnlt(s).

Examples of phosphorus-containing inorganic detergency builders, when present, include the water-soluble salts, especially-alkali metal pyrophosphates, orthophosphates, metaphosphates, 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, when present, include water-soluble alkali metal carbonates, bicarbonates, silicates and crystalline and amorphous aluminosilicates. Specific examples include sodium carbonate (with or without calcite seeds), potassium carbonate (with or without calcite seeds), sodium and potassium bicarbonates and silicates.

Examples of organic detergency builders, when prese, include the alkali methyl, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl carboxylates and polyhydroxysulphonates.

Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, melitic acid, benzene polycarboxylic acids and citric acid.

It is preferred that the compositions according to the invention be alkaline, that is at a concentration of 1 g/l or more in distilled water at 25"C the pH should be at least 8, preferably at least 10. To this end the compositions may include a water-soluble alkaline salt.

This salt may be a detergency builder or a non-building alkaline material.

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

Examples of other ingredients which may be present in the composition include polymers containing carboxylic or sulphonic acid groups in acid form or wholly or partially neutralised to sodium or potassium salts, the sodium salts being preferred. Preferred polymers are homopolymers and copolymers of acrylic acid and/or maleic acid or maleic anhydride. Of especial interest are polyacrylates, acrylic/maleic acid copolymers, and acrylic phosphinates.

Suitable polymers, which may be used alone or in combination, include the following: polyacrylic acids, for example Versicol (Trade Mark) E5, E7 and E9 ex Allied Colloids, Narlex (Trade Mark) LD 30 and LD 34 ex National Adhesives and Resins Ltd, Acrysol (Trade Mark) LMW-10, LMW-20, LMW-45 and A1-N ex Röhm & Haas, and Sokalan (Trade Mark) PA-20, PA-40, PA-70 and PA110 ex BASF; ethylene/maleic acid copolymers, for example the EMA (Trade Mark) series ex Monsanto; methyl vinyl ether/maleic acid copolymers, for example, Gantrez (Trade Mark) AN 119 and AN 149 ex GAF Corporation; acrylic acid/maleic acid copolymers, for example, Sokalan (Trade Mark) CP4, CP5 and CP7 ex BASF, and the Alccperse (Trade Mark) series ex Alco;; acrylic phosphinates, for example, DKW (Trade Mark) 125 ex National Adhesives and Resins Ltd, and the Belsperse (Trade Mark) series ex Ciba-Geigy.

The molecular weights of homopolymers and copolymers are generally 1000 to 150,000, preferably 1500 to 100,000- The amount of any polymer may lie in the range from 0.5 to 5% by weight of the composition. Other suitable polymeric materials are cellulose ethers such as carboxy methyl cellulose, methyl cellulose, hydroxy alkyl celluloses, and mixed ethers, such as methyl hydroxy ethyl cellulose, methyl hydroxy propyl cellulose; and methyl carboxy methyl cellulose. Mixtures of different cellulose ethers, particularly mixtures of carboxy methyl cellulose and methyl cellulose, are suitable. Polyethylene glycol of molecular weight from 400 to 50,000, preferably from 1000 to 10,000, and copolymers of polyethylene oxide with polypropylene oxide are suitable as also are copolymers of polyacrylate with polyethylene glycol.Polyvinyl pyrrolidone of molecular weight of 10,000 to 60,000 preferably of 30,000 to 50,000 and copolymers of polyvinyl pyrrolidone with other poly pyrrolidones are suitable.

Polyacrylic phosphonates and related copolymers of molecular weight 1000 to 100,000, in particular 3000 to 30,000 are also suitable.

Further examples of other ingredients which may be present in the composition include fabric softening agents such as fatty amines, fabric softening clay materials, lather depressants, oxygen-releasing bleaching agents such as sodium perborate and sodium percarbonate, peracid bleach precursors, chlorine-releasing bleaching agents such as trichloroisocyanuric acid, inorganic salts such as sodium sulphate, and, usually present in very minor amounts, fluorescent agents, perfumes including deodorant perfumes, enzymes such as cellulases, proteases and amylases, germicides and colourants.

The detergent compositions according to the invention may be in any suitable form including powders, bars, liquids and pastes. For example suitable liquid compositions may be non-aqueous or aqueous, the latter being either isotropic or lamellar structured. The compositions maybe prepared by a number of different methods according to their physical form. In the case of granular products they may be prepared by dry-mixing or coagglomeration. A preferred physical form is a granule incorporating a detergency builder salt. This may be prepared by conventional granulation techniques, or by spray-drying at least part of the composition. In this process a slurry is prepared containing the heat-insensitive components of the composition such as the surfactant system, builder material and filler salt.The slurry is spray-dried to form base powder granules with which any solid heat-sensitive ingredients may be mixed, such ingredients including bleaches and enzymes. The specified nonionic surfactants can be liquified by melting or solvent dissolution 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 A number of examples end comparative examples were carried out. Each example compared the soil removal (specifically triolein removal) from polyester test cloths using various proportions of two surfactants. The test cloths varied from one Example to another. Consequently individual Examples reveal whether a particular pair of surfactants did or did not co-operate to give synergy when in admixture, but the numerical results in any one Example cannot be compared directly with those of another.

The experimntal conditions were the same in each case. Wash liquors -are used to wash a fabric los6 in a Tergotometer at a liquor to cloth ratio of 40:1. Washing was carried out at 40"C for 20 minutes, with agitation at 70rpm. The load consisted of a number of polyester test cloths to which had previously been applied an amount of C14 labelled triolein. Measurement of the level of labelled triolein after washing, using radiotracer techniques gave an indication of the degree of detergency (soil removal).

Experiments were carried out using vinylidene sulphonates obtained from symmetrical vinylidenes (i.e. R1 and R2 the same). Experiments were also carried out using internal olefin sulphonates obtained from internal olefins which were random mixtures with the olefin at various positions (but with an alpha olefin content of less than 2%).

Nonionic surfactants were C12 alcohol ethoxylated with differing average amounts of ethylene oxide, as stated below, and stripped to remove unethoxylated alcohol. Some other nonionic surfactants were also used. These were C10 and C12 alkyl glyceryl monoethers and coconut monoethanolamide.

C12 alcohol with average 3 ethylene oxide residues has an HLB of approximately 8.3. C12 alcohol with average 8 ethylene oxide residues has an HLB value of approximately 13.1. Coconut ethanolamide has an HLB value of approximately 7.9. The HLB values of the glyceryl monoethers are not known precisely but they are well below 10.

In a first series of experiments for each tested composition, wash liquors were made up containing 1 g/l of the surfactant mixture and a 0.1 molar mixture of sodium chloride and sodium carbonate giving an ionic strength of 0.1 moles/litre (to represent the electrolyte level which would derive from other components of the composition in practice) and to give a pH of 10.

Results of both series of experiments are given in the following Table 1 (vinylidene sulphonates) and Table 2 (internal olefin sulphonates).

TABLE 1 Example No: 1 2 3 4 5 No of C atoms in vinylidene C16 C16 C18 C18 C20 Ethylene oxide residues on C12 alcohol 3 8 3 8 3 Approx HLB value 8.3 13.1 8.3 13.1 8.3 Vinylidene sulphonate/ nonionic ratio % triolein removal 100 : 0 13 13 18 18 8 80 : 20 - 14 21 18 8 75 : 25 29 - - - 60 : 40 22 9 19 11 9 50 : 50 19 8 19 13 9 40 : 60 11 8 17 13 9 30 : 70 11 - - - 20 : 80 5 13 8 18 7 0 : 100 2 23 2 23 1 TABLE 2 Example No: 6 7 8 9 10 11 12 13 No of C atoms in internal olefin 14 16 18 18 20 16 16 Nonionic surfactant* C123EO C123EO C123EO C128EO C128EO C10GME C12GME CEA Apporx HLB value 8.3 8.3 8.3 13.1 13.1 < 10 < 10 7.9 Olefin sulphonate/ nonionic ratio % triolein removal 100 : 0 5 11.3 35.2 45.6 8.1 19.1 19.1 19.1 90 : 10 - - - - - - - - 22.2 80 : 20 23 24.2 45.9 - 16.1 29.7 29.9 29.4 70 : 30 - - - 39.6 - - 24.1 32.4 60 : 40 60 49.7 51.9 - 23.3 24.6 18.6 33.6 50 : 50 - - - 38.8 24.7 17.6 - 40 : 60 49 64.2 38.2 - 23.3 11.1 9.5 23.7 20 : 80 5 5.1 3.2 - 24.0 5.9 5.5 12.0 0 : 100 0 0 0 62.2 24.0 1.1 3.8 4.8 * Cn3EO denotes Cn alcohol with average 3 ethylene oxide residues.

CnGME denotes Cn alkyl glycerol monoether.

CEA denotes coconut monoethanolamide.

Examples 1 and 3 in Table 1 and Examples 6-8 and 11-13 in Table 2 show that greater detergency occurs with a mixture of the low HLB nonionic and sulphonate than with either of these components alone. This synergistic effect is not observed with the higher HLB nonionic used in Examples 2, 4 and 9 but a small amount of synergy is observed in Example 10 when this nonionic is used with a sulphonate having more than 18 carbon atoms.

Further experiments were carried out using C16 internal olefin sulphonate and the low HLB nonionic at varying ionic strengths. The exper;ments were done both at 40"C and at 20"C. For a comparison a mixture of linear alkyl benzene sulphonate (LAS) and the same nonionic was also used. The ratio of anionic to nonionic was the ratio which had previously been found to give maximum triolein removal at the ionic strength and temperature concerned.

Results are set out in Table 3 below and show that better detergency is found at higher levels of electrolyte. TABLE 3 % triolein removal at optimum composition Electrolyte C16 IOS/C12 3EO (40 C) LAS/C12 3EO (40 C) C16 IOS/C12 3EO (20 C) ionic strength 0.005M 35 30 0.01M - 35 43 0.02M 48 53 49 0.05M 58 60 58 0.1M 57 65 55 It can also be seen from this Table that IOS and low HLB nonionic compares well with LAS and nonionic under conditions of low temperature and low electrolyte.

Claims (13)

1. A detergent composition including a surfactant system the major proportion of which consists of: i) an anionic surfactant material which is a) an internal olefin sulphonate derived from an internal olefin having the general formula: R1 - CH = CH - R2 (I) or b) a vinylidene sulphonate derived from a vinylidene having the general formula:

or c) a mixture thereof, R1 and R2 being alkyl groups which are the same or different and have 10 to 16 carbon atoms in total; and ii) a nonionic surfactant material having an HLB value of not more than 10.5, the weight ratio of (i) to (ii) lying between 9:1 and 1:9.

2. A composition according to claim 1 wherein the ratio of (i) to (ii) lies between 4:1 and 1:4.

3. A composition according to claim 1 or claim 2 wherein the nonionic surfactant is an alkoxylated, preferably an ethoxylated, nonionic surfactant.

4. A composition according to any one of the preceding claims wherein the composition contains 5 to 95% by weight of water-soluble salt.

5. A composition according to any one of the preceding claims wherein at least a major proportion of the anionic surfactant in the surfactant system is internal olefin sulphonate and the composition contains 10 to 60% of insoluble detergency builder together with 5 to 50% of water-soluble salt.

6. A composition according to any one of the preceding claims in which the nonionic surfactant has an HLB of less than 10.

7. A composition according to any one of the preceding claims which contains sufficient alkaline salt to render a pH of at least 8, preferably at least 10, when the composition is added to distilled water at 25"C in an amount of at least 1 g/litre.

8. A composition according to any one of the preceding claims which is a granular composition suitable for washing fabrics.

9. A composition according to any one of the preceding claims which contains at least one of: fabric softening agents fabric softening clay lather booster lather depressant bleaching agent fluorescent agent organic polymer containing carboxylic or sulphonic acid groups perfume, and enzyme.

10. A method of cleaning comprising contacting soiled material with an aqueous liquor which is a solution of a surfactant system, the major proportion of which consists of: i) an anionic surfactant material which is a) an internal olefin sulphonate derived from an internal olefin having the general formula: R1 - CH = CH - R2 (I) or b) a vinylidene sulphonate derived from a vinylidene having the general formula:

or c) a mixture thereof, R1 and R2 being alkyl groups which are the same or different and have 10 to 16 carbon atoms in total; and ii) a nonionic surfactant material having an HLB value of not more than 10.5, the weight ratio of (i) to (ii) lying between 9:1 and 1:9.

11. A method according to claim 10 wherein the wash liquor contains electrolyte at an ionic strength of at least 4 x 10-3 moles/litre.

12. A method according to claim 10 wherein at least a major proportion of the anionic surfactant in the surfactant system is internal olefin sulphonate and the wash liquor contains electrolyte at an ionic strength in the range from 0.005 to 0.1 moles/litre.

13. A method according to any one of claims 10 to 12 wherein the wash liquor has a pH of at least 8.