GB2046321A

GB2046321A - Bleaching compositions

Info

Publication number: GB2046321A
Application number: GB7913486A
Authority: GB
Original assignee: Lankro Chemicals Ltd
Current assignee: Lankro Chemicals Ltd
Priority date: 1979-04-18
Filing date: 1979-04-18
Publication date: 1980-11-12

Abstract

A thickened bleaching composition comprises water, an alkali-metal hypochlorite and a hypochlorite-soluble salt, preferably an alkali-metal salt, of a phosphated, optionally alkoxylated, fatty acid alkanolamide surfactant as the thickening agent. The composition is suitably viscous and thixotropic and thus readily adheres to treated surfaces, minimising waste by run-off and increasing the effective utilisation of the chlorine present in the hypochlorite.

Description

SPECIFICATION Bleaching compositions This invention relates to bleaching compositions, more particularly to thickened bleaching compositions having a viscosity considerably in excess of that of water.

Compositions consisting essentially of aquequs solutions of alkali-metal hypochlorites, particularly sodium hypochlorite, are well known for their disinfectant and bleaching effect and are widely used both for industrial applications and for general domestic purposes. For example, large quantities of such compositions are used as bleaching agents in the treatment of fabrics and as bleaching and disinfectant cleaners for lavatory pans, urinals, drains and wastepipes. The compositions employed generally contain up to 15% by weight, preferably from 5 to 10% by weight, available chlorine. Commercially available compositions normally contain in addition a small amount, e.g. up to 2% by weight, of free caustic alkali.

A major disadvantage of such compositions is that they are of low viscosity, similar to that of water, and thus do not readily adhere to treated surfaces long enough for the available chlorine to be effectively utilized.

Accordingly, attempts have been made previously to provide more viscous compositions, for example, having viscosities at 25"C of from 10 to 200 centistokes (cS), by the addition of suitable thickening agents.

Difficulties have been encountered however in finding thickening agents which are sufficiently chlorineresistant and which are sufficiently soluble in the basic aqueous hypochlorite solution.

One proposal hitherto employed has been to use a soap i.e. an alkali metal salt of a fatty acid such as sodium stearate, as the thickening agent. However, the available useful soaps are in general difficuit to solubilise into aqueous hypochlorite solutions and use has therefore had to be made of various soap/water solubilising agents in combination with the soap. This again has involved the problem of finding solubilising agents which are sufficiently chlorine-resistant. Examples of hypochlorite-soluble surface active agents that have been found to be effective as solubilising agents for soap are amine oxides and long-chain substituted betaines but these materials although chlorine-resistant are relatively expensive.

It has now been found that bleaching compositions may be thickened very effectively and without the necessity of using a solubilising agent by means of a hypochlorite-soluble slat of a phosphated fatty acid alkanolamide or alkoxylated fatty acid alkanolamide as the thickening agent.

Accordingly, the present invention provides a bleaching composition comprising water, an alkali-metal hypochlorite and a hypochlorite-soluble salt of a phosphated, optionally alkoxylated, fatty acid alkanolamide surfactant as a thickening agent.

The alkali metal hypochlorite employed in the above composition is preferably sodium hypochiorite but potassium or lithium hypochlorite for example may also be used if desired.

The hypochlorite-soluble salt of a phosphated fatty acid alkanolamide or phosphated alkoxylated fatty acid alkanolamide employed as the thickening agent in the bleaching composition of the invention may be, for example, an amine salt but is preferably an alkali metal salt, the sodium salt being particularly preferred. The fatty acid moiety of this component preferably contains from 9 to 22 carbon atoms, more preferably from 9 to 19 carbon atoms, especially from 11 to 15 carbon atoms, per molecule. The fatty acid moiety is preferably derived from a straight or branched chain, substantially fully saturated organic acid, for example, decanoic, lauric, stearic, myristic, palmitic, or mixtures thereof such as tallow or coconut fatty acids, particularly coconut fatty acids.Such mixtures as tallow and coconut fatty acids may, if desired, be suitably hardened although this is unnecessary as the small degree of unsaturation in such materials is usually found to be quite acceptable. The alkanolamide moiety of the fatty acid alkanolamide may be derived from a mono- or di-alkanolamide and preferably contains from 1 to 20 carbon atoms, preferably from 1 to 6 carbon atoms per molecule, for example mono- or di-ethanolamide or mono- or di-isopropanolamide.

Examples of fatty acid mono- or di-alkanolamides are tallow monoethanolamide, tallow diethanolamide, coconut monoethanolamide and coconut diethanolamide. These are available commercially as mixtures of related compounds, coconut monoethanolamide and coconut diethanolamide being available under the trade names Ethylan LM and Ethylan LD respectively.

In accordance with the invention the fatty acid alkanolamide may be alkoxylated and when this is the case the degree of alkoxylation is preferably from 1 to 20, more preferably from 1 to 14, particularly from 2to 10, moles of alkylene oxide per mole of alkanolamide. It should be noted however that the preferred degrees of alkoxylation are in general related to the size of the fatty acid moiety of the alkanolamide. Thus, for example, when the fatty acid moiety contains 9 carbon atoms the degree of alkoxylation may suitably be about 2, when the fatty acid moiety contains 13 carbon atoms the degree of alkoxylation may suitably be about 5 and when the fatty acid moiety contains 19 carbon atoms the degree of alkoxylation may suitably be about 9.The alkoxide used is preferably a C1.4 alkoxide, most preferably ethylene oxide or ethylene oxide containing a small amount, e.g. up to 10% by weight, of propylene oxide. Examples of preferred alkoxylated fatty acid alkanolamides are ethoxylates of coconut monoethanolamide and coconut diethanolamide having 2 moles of ethoxylate per mole of monoethanolamide or diethanolamide, the former being commercially available under the trade name Ethylan LM2.

The phosphated alkanolamides and phosphated alkanolamide alkoxylates employed as thickening agents in the compositions of the present invention are of complex structure but the preferred compounds at least are believed to be compounds having the general formula:

wherein : (a) R1 is alkyl, preferably containing from 8 to 21, more preferably 8 to 18, especially 10 to 14, carbon atoms; (b) R2 is hydrogen, alkyl e.g. alkyl containing from 1 to 6 carbon atoms, a group of the formula -R3O4R4OtH or a group of the formula

(c) R3 is alkylene, preferably containing from 1 to 20 carbon atoms, more preferably containing from 2 to 6 carbon atoms, especially 2 or3 carbon atoms; (d) R4 is alkylene, preferably containing from 1 to 4 carbon atoms, most preferably an ethylene group;; (e) n is zero or an integer, preferably zero or an integer of from 1 to 20, more preferably zero or an integer of from 1 to 14, particularly an integer of from 2 to 10.

(f) M is alkali metal, preferably sodium; (g) Xis a group of the formula -OM or a group of the formula

The compounds of the above-defined general formula preferably contain no more than six nitrogen atoms, more preferably from 1 to 4 nitrogen atoms, particularly 1 or 2 nitrogen atoms.

It will be appreciated that in the compounds of the general formula specified above, any group R1, R2, R3, R4, M or X may be the same as or different from any other group R1, R2, R3, R4, M or X respectively. For instance, in the case of a group of the formula4R40twherein n is an integer greater than one, each R4 may be a different alkylene group although preferably all are ethylene groups optionally with a small proportion e.g. up to 10% by weight, being propylene groups. Furthermore R4 and n in any group4R40imay be the same as or different from R4 and n respectively in any other group4R40tin the molecule.

The phosphated alkanolamides and alkanolamide alkoxylates employed in the present invention may be prepared by directly phosphating in conventional manner the basic alkanolamide or alkanolamide alkoxylate using as the phosphating agent, for example, phosphoric acid (of various grades) or phosphorous pentoxide (P2O). The phosphated product will normally be a mixture of the mono- and di-esters, the actual proportions thereof depending upon the type of phosphating agent used. Phosphoric acid tends to produce a higher proportion of the mono-ester whereas phosphorous pentoxide tends to produce equal amounts of the two.

For the compositions of the present invention the mono-esters, or mixtures which are predominantly mono-esters, are preferred, corresponding to compounds of the above-specified general formula wherein X is a group of the formula -OM. The alkali metal salt of the phosphated product, as preferably employed in the present compositions, may be prepared for example by reacting the phosphated product with the appropriate alkali metal hydroxide.

If desired the bleaching compositions in accordance with the invention may comprise one or more additional chlorine-resistant surfactants to impart greater detergency and/or clarity to the composition. For example the compositions may comprise as an additional surfactant an amine oxide containing a C8-C18 alkyl group, e.g., lauryl dimethylamine oxide. Alternatively a substituted betaine containing a C8-C18 alkyl group may be employed.

However, a particularly preferred additional surfactant which may be employed in the present composition is a hypochlorite-soluble salt, preferably an alkali metal salt, of a phosphated aliphatic or aromatic alcohol alkoxylate. These phosphated products, as in the case of the above-described phosphated alkanolamides, are predominantly mono- or di-phosphate esters, or mixtures thereof, and the preferred alkali metal salts have the general formula:

wherein: (a) R is aikyl, preferably unsubstituted alkyl containing from 4 to 18, particularly 9 to 15, carbon atoms, or aryl, preferably phenyl or alkyl-substituted phenyl wherein the alkyl substituent contains from 8 to 12 carbon atoms; (b) R4 is as hereinbefore defined; (c) mis an integer of from 2 to 40; (d) M is alkali metal, preferably sodium; and (e) Y is a group of the formula -OM or a group of the formula Ro4R402; Preferably m is an integer of from 2 to 20, the particularly preferred values being towards the iower end of this range, e.g. from 4 to 9. However, it should be noted that the preferred values of m are related to the size of the hydrophobic group R. For example, if R is an alkyl group containing about 8 carbon atoms or an unsubstituted phenyi group, m may suitably be about 4; if R is effectively a Cur215 alkyl mixture, m may suitably be about 7; and if R is a nonyl-phenyl group, m may suitably be about 9.

The phosphated alcohol alkoxylates may be prepared in a manner analogous to that described above for the phosphated alkanolamide thickening agents by phosphating an appropriate alcohol alkoxylate using, for example, a phosphoric acid or phosphorous pentoxide as the phosphating agent. It is again preferred for the purposes of the present invention that the conditions should be such as to favour the formation of mono-esters, corresponding to compounds in accordance with the foregoing formula wherein Y is a group of the formula -OM.

Particularly preferred alkali-metal salts of phosphated alcohol alkoxylates for use in the compositions of the present invention are the sodium salts of: (phenol + 4 moles ethylene oxide)phosphate; (nonyl-phenol + 9 moles ethylene oxide)phosphate - Phospholan PNP-9; (iso-octanol + 4 moles ethylene oxide)phosphate; (Cg.11 linear alcohol mixture + 6 moles ethylene oxide)phosphate; and (C,215 linear alcohol mixture + 7 moles ethylene oxide)phosphate - Phospholan PDE-7.

The concentration of alkali metal hypochlorite employed in the bleaching compositions of the present invention should generally be such as to provide an available chlorine content in the range of from 1% to 10% by weight, preferably from 5% to 10% by weight, based on the total weight of the composition. The concentration of phosphated alkanolamide or phosphated alkanolamide alkoxylate employed as the thickening agent in the compositions naturally depends upon the particular level of alkali metal hypochlorite and upon the degree of thickening required.However, an amount of thickening agent in the range 0.1 to 3.0% by weight is generally satisfactory, whilst the most suitable viscosity increase can be obtained using from 0.15to 1.5% by weight, particularly 0.25 to 1.0% by weight When an additional surfactant such as a phosphated alcohol alkoxylate is incorporated into the compositions of the invention it is preferably employed in an amount such as to provide a weight ratio of thickener to surfactant of from 80:20 to 10:90, preferably from 60:40 to 30:70.

The bleaching compositions of the invention may optionally comprise one or more additional ingredients as conventionally employed in such compositions. For example, the compositions may if desired comprise a caustic alkali, preferably in an amount of from 0.5 to 2% by weight The caustic alkali will usually be sodium hydroxide, but potassium hydroxide and lithium hydroxide may also be used. The compositions may also contain chlorine-stable perfumes or colourants if required, usually in an amount of from 0.05 to 0.2% by weight. Atypical perfume is Pineneedle LB 28.

The bleaching compositions of the present invention are not only viscous but are generally also thixotropic, which properties result in the composition adhering well to the sides of say, a lavatory pan, minimising waste by run-off and thus increasing the effective utilisation of the chlorine present in the bleach.

In addition, the compositions are relatively stable as regards chlorine content. Thus, in general the compositions may exhibit a viscosity at 20"C of from 10 to 120 centistokes (cS) and a resistance to chlorine equivalent to a chlorine loss of not more than 20% by weight after storage at 20"C for 3 months.

It is to be understood that the invention also includes a composition suitable for thickening an aqueous solution of an alkali metal hypochlorite which composition comprises a mixture of a phosphated optionally alkoxylated fatty acid alkanolamide surfactant as hereinbefore described and a chlorine-resistant additional surfactant, preferably a phosphated aliphatic or aromatic alcohol alkoxylate as hereinbefore described.

The present invention will be further illustrated by the following Examples: EXAMPLE 1 (a) Preparation of the sodium salt of {coconut monoethanolamide + 2 moles ethylene oxide)phosphate Tetraphosphoric acid (187.39) was added over a period of 1 hour under agitation to coconut monoethanolamide + 2 moles ethylene oxide (6629) which had previously been heated to 80"C. The reaction mixture was then heated to 1 OO"C and maintained at that temperature for 1 hour before being allowed to cool. A sample of the resulting "free acid" phosphate ester product (249) was then added to an aqueous solution of sodium hydroxide (49 NaOH predissolved in 729 of water) to produce the desired sodium salt.

(b) To a solution of the sodium salt of (coconut monoethanolamide + 2 moles ethylene oxide) phosphate prepared in (a) (1.5g) in water (18.59) was added, with agitation, aqueous sodium hypochlorite (809) containing 12.5% available chlorine to yield a bleaching composition in accordance with the invention containing 10% available chlorine and having a viscosity at 20"C of 37 cS. After storage at 20"C for 3 months 88% of the original available chlorine of the composition was found to have been retained.

EXAMPLES 2-6 Further alkali metal salts of phosphated alkanolamide alkoxylates were prepared substantially in the manner described in Example 1 and were used in the preparation of bleaching compositions in accordance with the invention, all of which had an initial available chlorine content of 10% by weight. In Examples 5 and 6 an additional surfactant was also added to the composition. The various components and the proportions thereof in the respective compositions and also the viscosity and stability test data therefor are set forth in the following Table. The proportions of phosphated alkanolamide and additional surfactant are expressed in percentages by weight, based on the total weight of the composition.

TABLE Example Thickener Additional Surfactant Viscosity % Chlorine No. at 20 C. Retention Type Amount C9-11 alcohol + lauryl (cS).

(% by weight) 6 EO phosphate dimethylamine (sodium salt) oxide coconut monoethanolamide 2 + 2 EO phospate 0.5 - - 42 89 (sodium salt) coconut monoethanolamide 3 + 6 EO phosphate 0.3 - - 29 87 (sodium salt) coconut diethanolamide 4 + 2 EO phosphate 0.25 - - 26 88 (sodium salt) coconut monoethanolamide 5 + 2 EO phosphate 0.15 0.15 - 30 89 (sodium salt) conconut monoethanolamide 6 + 2 EO phosphate 0.2 - 0.7 28 86 (sodium salt)

Claims

1. A bleaching composition comprising water, an alkali-metal hypochlorite and a hypochlorite-soluble salt of a phosphated optionally alkoxylated, fatty acid alkanolamide surfactant as a thickening agent.

2. A composition as claimed in claim 1 wherein the fatty acid moiety of the phosphated alkanolamide contains from 9 to 22 carbon atoms.

3. A composition as claimed in claim 2 wherein the fatty acid moiety contains from 9 to 19 carbon atoms.

4. A composition as claimed in claim 1 wherein the fatty acid moiety of the phosphated alkanolamide is derived from one or more of decanoic, lauric, stearic, myristic and palmitic acid.

5. A composition as claimed in claim 1 wherein the fatty acid moiety of the phosphated alkanolamide is derived from tallow or coconut fatty acids.

6. A composition as claimed in any one of the preceding claims wherein the alkanolamide moiety of the phosphated alkanolamide contains from 1 to 20 carbon atoms.

7. A composition as claimed in claim 6 wherein the alkanolamide moiety contains from 1 to 6 carbon atoms.

8. A composition as claimed in any one of claims 1 to 5 wherein the alkanolamide is a mono- or diethanolamide or a mono- or di- isopropanolamide.

9. A composition as claimed in any one of the preceding claims wherein the alkoxylated fatty acid alkanolamide has a degree of alkoxylation of from 1 to 20 moles of alkylene oxide per mole of alkanolamide.

10. A composition as claimed in claim 9 wherein the degree of alkoxylation is from 2 to 10 moles of alkylene oxide per mole of alkanolamide.

11. A composition as claimed in any one of the preceding claims wherein the fatty acid alkanolamide is alkoxylated with a C1 4 alkoxide.

12. A composition as claimed in claim 11 wherein the alkoxide is ethylene oxide or ethylene oxide containing a small amount of propylene oxide.

13. A composition as claimed in claim 1 wherein the alkoxylated fatty acid alkanolamide is an ethoxylate of coconut monoethanolamide or coconut diethanolamide having 2 moles of ethoxylate per mole of monoethanolamide or diethanolamide.

14. A composition as claimed in any one of the preceding claims wherein the hypochlorite-soluble salt of the phosphated, optionally alkoxylated, fatty acid alkanolamide is an alkali metal.

15. A composition as claimed in claim 14, wherein the hypochlorite-soluble salt is a sodium salt.

16. A composition as claimed in claim 1, wherein the hypochlorite-soluble salt of a phosphated, optionally alkoxylated, fatty acid alkanolamide is a compound having the general formula:

wherein: (a) R1 is alkyl; (b) each independent R2 is hydrogen, alkyl, a group of the formula -R304R40iH or a group of the formula

(c) R3 is alkylene; (d) R4 is alkylene; (e) n is zero or an integer; (f) M is alkali metal; and (g) Xis a group of the formula -OM or a group of the formula

17.A composition as claimed in claim 16 wherein R' is alkyl containing from 8 to 18 carbon atoms; R2 is hydrogen, a group of the formula -R304R40iH or a group of the formula

R3 is alkylene containing from 1 to 20 carbon atoms; R4 is alkylene containing from 1 to 4 carbon atoms; and n is zero or an integer of from 1 to 20.

18. Acomposition as claimed in claim 15 or claim 16 wherein R3 is alkylene containing 2 or3 carbon atoms.

19. A composition as claimed in any one of claims 15 to 17 wherein R4 is ethylene.

20. A composition as claimed in any one of claims 15 to 18 wherein n is an integer of from 2 to 10.

21. A composition as claimed in any one of claims 16 to 20 wherein M is sodium.

22. A composition as claimed in any one of claims 16 to 21, wherein the hypochlorite-soluble salt of a phosphated, optionally alkoxylated fatty acid alkanolamide contains from 1 to 4 nitrogen atoms.

23. A composition as claimed in any one of the preceding claims comprising one or more additional chlorine-resistant surfactants.

24. A composition as claimed in claim 22, wherein the additional surfactant is an amine oxide containing a C9-C18 alkyl group or a substituted betaine containing a C8-C18 alkyl group.

25. A composition as claimed in claim 22, wherein the additional surfactant is a hypochlorite-soluble salt of a phosphated aliphatic or aromatic alcohol alkoxylate.

26. A composition as claimed in claim 25, wherein the hypochlorite-soluble salt of a phosphated alcohol alkoxylate is a compound having the general formula:

wherein: (a) R is alkyl or aryl; (b) R4 is as defined in any one of claims 15, 16 and 18; (c) mis an integer of from 2 to 40; (d) M is alkali metal; and (e) Y is a group of the formula -OM or a group of the formula RO+R4Ot

27. A composition as claimed in claim 26, wherein R is alkyl containing from 4 to 18 carbon atoms or phenyl.

28. A composition as claimed in claim 27, wherein R is alkyl-substituted phenyl wherein the alkyl substituent contains from 8 to 12 carbon atoms.

29. A composition as claimed in any one of claims 26 to 28, wherein m is an integer of from 2 to 20.

30. A composition as claimed in any one of claims 26 to 29 wherein M is sodium.

31. A composition as claimed in claim 25, wherein the additional surfactant is the sodium salt of: (phenol + 4 moles ethylene oxide) phosphate; (phenol + 9 moles ethylene oxide) phosphate; (iso-octanol + 4 moles ethylene oxide) phosphate; (Cg.ll linear alcohol mixture + 6 moles ethylene oxide) phosphate; or (C12-15 linear alcohol mixture + 7 moles ethylene oxide) phosphate.

32. A composition as claimed in any one of the preceding claims, wherein the hypochlorite is sodium hypochlorite.

33. A composition as claimed in any one of the preceding claims, wherein the alkali-metal hypochlorite is present in an amount such as to provide an available chlorine content of from 1 to 10% by weight based on the total weight of the composition.

34. A composition as claimed in any one of the preceding claims, wherein the phosphated alkanolamide thickening agent is present in an amount of from 0.1 to 3.0% by weight, based on the total weight of the composition.

35. A composition as claimed in claim 33, wherein the phosphated alkanolamide thickening agent is present in an amount of from 0.25 to 1.0% by weight.

36. A composition as claimed in any one of claims 23 to 33 which contains an additional surfactant in an amount such as to provide a weight ratio of thickener to additional surfactant of from 80:20 to 10:90.

37. A composition as claimed in claim 36, wherein the weight ratio of thickener to additional surfactant is from 60:40 to 30:70.

38. A composition as claimed in any one of the preceding claims which additionally comprises from 0.5 to 2% by weight of a caustic alkali.

39. A composition as claimed in any one of the preceding claims which additionally comprises a perfume or colourant.

40. A composition as claimed in claim 1, substantially as hereinbefore described in any one of Examples 1 to 6.

41. A composition suitable for thickening aqueous alkali metal hypochlorite solutions comprising a phosphated, optionally alkoxylated, fatty acid alkanolamide surfactant and a chlorine-resistant additional surfactant.

42. A composition as claimed in claim 41, further defined by one or more of the specific features of any of claims 2 to 22, 24 to 31,36 and 37.