Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/39—Organic or inorganic per-compounds
  • C11D3/3947—Liquid compositions

Definitions

• the present invention relates to improvements in bleaching and/or hygiene compositions comprising peroxy carboxylic acids.
• the invention relates to bleaching and/or hygiene compositions for use on hard surfaces such as ceramics, plastics and metals, or in aqueous solutions contacting solid surfaces.
• bleaching agent and hygiene agent are used interchangeably.
• Aqueous-insoluble or partially insoluble peracids have also been investigated with particular reference to their use in fabric bleaching compositions and in machine dishwashing applications, both in liquid and powder compositions.
• a thickening agent must generally be present in order to suspend the insoluble i.e. particulate, bleaching agent.
• a constraint which is placed upon the choice of thickening system is that its chemical and physical properties must be such that it is stable in the presence of the reactive, peracid bleaching and/or hygiene agents.
• a further constraint on the overall formulation is that the peracid should be chemically stable in the presence of the thickening agent.
• US patent 3996152 discloses stable low-pH gels containing peroxyacid bleach particles in a non-starch thickening agent.
• Aqueous suspensions of the solid hygiene agent diperoxy- dodecanedioic acid are known for use as pourable bleaching compositions from EP 0176124.
• Another form of DPDA suspension useful as an aqueous liquid bleaching composition is disclosed in EP 0160342.
• DPDA is an organic peroxy acid, relatively stable to decomposition, odourless and particularly effective as an anti-bacterial agent as compared with hydrogen peroxide.
• US 4100095 discloses the stabilisation of peroxyacid bleaches by the use of certain exotherm control agents so as to prevent explosion. These agents may be selected from magnesium sulphate, sodium sulphate, boric acid and potassium sulphate. Sodium sulphate is commonly present in commercial DPDA in order to reduce the explosive tendency.
• EP 0412599 provides an alternative solution by using glycols as control agents.
• European patent application EP 0160342 (Unilever, 1984) discloses aqueous liquid bleaching compositions containing organic peroxyacid particles having a solubility of less than about 1% in water, suspended in an acidic surfactant- structured liquid containing alkyl benzene sulphonic acid and electrolyte.
• the Ph of the compositions disclosed in EP 160342 preferably ranges from 2-5, the preferred peroxy acid is DPDA. It is believed that the combination of alkyl benzene sulphonic acid and electrolyte forms a lamellar-dispersion thickening system which suspends the particles.
• EP 0435379 (AKZO, 1989) relates to the use of i idoperoxy- carboxylic acids (as defined therein) in bleaching compositions in soaking detergents and dishwashing detergents.
• Preferred compositions include e-N-N- phthaloyl-amino-peroxy-caproic acid (PAP) and DPDA, as mentioned above.
• PAP is considerably less explosive than DPDA and has comparable stability to decomposition.
• PAP is less effective as a hygiene agent than DPDA on a weight for weight basis.
• the formulations disclosed in EP 0435379 comprise 0.1-35%, preferably 2-10%wt sulphate and 0.5-40%wt, preferably 2- 20%wt of alkyl benzene sulphonic acid as surfactant. It is believed that the presence of the relatively inexpensive sulphate salt, as electrolyte, promotes thickening of the composition such that the level of the relatively expensive surfactant can be reduced without detriment to the suspending properties of the product.
• EP 0435379 states that the total alkyl benzene sulphonic acid content may vary from 0.5-40%wt, and the total level of surfactant may vary from 0-50%wt: i.e. although the presence of this component is an essential feature of the invention, the level of surfactant does not seem to have been thought of as particularly critical, although sufficient should be used to achieve the desired physical stability.
• the levels of PAP indicated in EP 0435379 are such that the active oxygen content of the compositions may range from 0.05-5%wt.
• PAP has a molecular weight of 277 and each molecule of PAP liberates one oxygen atom, consequently, the active oxygen content of pure PAP is 5.8%wt.
• An active oxygen content of 0.05%wt indicates a minimum level of l%wt PAP. Consequently, this document discloses that the PAP content can range from 1 to about 80% i.e. the document does not disclose any particular criticality in the levels of PAP.
• the Ph range preferred in EP 0435379 is acid: examples are given for pH 3.5.
• EP 442549 discloses the use of PAP as a bleaching agent in combination with secondary alkyl sulphonate and fatty acid as a suspending surfactant system. Such suspending surfactant systems are known to be bleach-stable.
• pH of the system is adjusted to pH 3.5-4.5.
• the compositions comprise sodium sulphate at a level such that the weight ratio of sodium sulphate to surfactant ranges from 1.67:1 to 1:3.67.
• compositions of EP 442549 suffer from the disadvantage that on storage white, needle-like crystals form in the composition and can be thrown down as a sediment. This leads to a loss of homogeneity in the composition and presents dosing problems. Moreover, the presence of crystals can abrade or scratch surfaces which are cleaned with the composition. More and worse, users can believe that the crystal-containing product has decomposed and discard the unused product, unnecessarily releasing the compound into the environment.
• compositions comprising relatively low levels of peroxycarboxylic acid can be improved by formulation in a specific pH range, further improved by the use of a specific surfactant and yet further improved by selection of a specific ratio of the quantity of selected sulphate salts and the preferred surfactant.
• an aqueous bleaching composition comprising: 0.5-15%wt of an peroxy carboxylic acid wherein the pH of the composition is such that it is above the pK a of the corresponding imido acid and below 6.0.
• the present invention relates to aqueous bleaching composition
• aqueous bleaching composition comprising: 0.5-15%wt of an peroxy carboxylic acid wherein the pH of the composition is such that it is above the pK a of the corresponding carboxylic acid and below 6.0.
• the pH of the composition is greater than 4.5 and less than 6.0. More preferably the pH falls into the range 4.5-6.0, and is most preferably around 5.5.
• the composition further comprises a surfactant component as a part of the thickening system.
• the surfactant is a sulphate or sulphonate anionic surfactant.
• the composition further comprises at least 3% of a sulphate salt other than a transition metal sulphate, and, preferably, 5-10% of one or more surfactant stable in the composition.
• a sulphate salt other than a transition metal sulphate and, preferably, 5-10% of one or more surfactant stable in the composition.
• commercially available sulphate and sulphonate surfactants often contain sodium sulphate as an impurity. Typical levels being around 5% Na 2 SO 4 /100% AD.
• the relative levels of these further components is such that the weight ratio of said surfactant to said sulphate is in the range 0.4-0.8:1, more preferably 0.6-0.8:1, as surfactant:sulphate (both being expressed as sodium salts) .
• transition metals either as sulphate salts or otherwise should be avoided as these promote the decomposition of the peracid.
• the weight ratio of surfactant:sulphate is around 0.66:1.
• the surfactant system comprises secondary alkane sulphonate.
• compositions are free of surfactants which contain benzene rings as these have not only been found to be less stable than compositions according to the present invention which comprises secondary alkane sulphonate but these surfactants may also present environmental problems.
• Preferred levels of secondary alkane sulphonate range from 4.0-10%wt with levels around 5.3wt% being most preferred.
• Most preferably the secondary alkane sulphonate is a C12-C18 average chain length secondary alkane sulphonate.
• the surfactant system further comprises a nonionic surfactant.
• nonionic surfactant are l-6%wt of an ethoxylated nonionic surfactant.
• the nonionic surfactant has an ethoxylation level of 3-12.
• the most preferred levels of the ethoxylated nonionic are l-3%wt on total product. Levels toward the lower limit of the range are employed where the optional fatty acid is present.
• the surfactant system further comprises fatty acids.
• Suitable fatty acids comprise alkyl chains having an average of 12-18 carbon atoms.
• the surfactant system comprises a mixture of at least secondary alkane sulphonate and fatty acid.
• the surfactant system comprises secondary alkane sulphonate, fatty acid and at least one nonionic surfactant.
• the most preferred weight ratios between these components are 4:1:1.
• the weight ratio of the alkali metal sulphate to total surfactant falls in the range 1:0.6- 1.25, more preferably 1:0.75-1.25.
• the molecular weight of a typical secondary alkane sulphonate is around 300, whereas the molecular weight of a typical nonionic surfactant of the 'Synperonic' (RTM) type is around 325.
• Fatty acids of the types described above have molecular weights around 220.
• the preferred mole ratios between the surfactants are 3-5:1 for the secondary alkane sulphonate to nonionic and 2-5:1 for the secondary alkane sulphonate to fatty acid.
• the molecular weight of sodium sulphate is 142.04, i.e. about half that of a typical secondary alkane sulphonate. It is preferable the molar ratio of the sulphate to the secondary alkane sulphonate is such that around 3-5 moles of sulphate are present for each mole of secondary alkane sulphonate. As the levels of sulphate present in technical grades of secondary alkane sulphonate are very much lower than this it will be appreciated that the mere use of technical grades of secondary alkane sulphonate will not achieve preferred embodiments of the invention and an addition of further sulphate will be required.
• the peroxy carboxylic acid is an imido peroxy- carboxylic acid, most preferably e-N-N-phthaloyl-amino- peroxycaproic acid (PAP) .
• PAP e-N-N-phthaloyl-amino- peroxycaproic acid
• peroxy-carboxylic acids are known as described above and from a publication entitled "TAED and new peroxycarboxylic acids as highly efficient bleach systems", 80th AOCS Meeting, Cincinnati OH, May 1989. It is believed that, particularly in those embodiments where the imido-peroxy-carboxylic acid is e-N-N-phthaloyl- amino-peroxycaproic acid (PAP) , the presence of even relatively low levels of the corresponding acid, e.g. the e- ⁇ - ⁇ -phthaloyl-amino-caproic acid, accelerates the formation of crystalline deposits in the formulation. It is believed the formation of these crystals is associated with the decomposition of the peracid.
• PAP e-N-N-phthaloyl- amino-peroxycaproic acid
• the starting materials particularly the peracid, should contain as little as possible of the corresponding acid and preferably, the ratio of the peroxy carboxylic acid to the corresponding carboxylic acid is higher than 96.5:3.5.
• compositions according to the present invention have a pH in the range 4.5-5.5 and comprise:
• compositions according to the invention may also be present in the compositions according to the invention. These include colouring agents, opacifiers, perfumes, and solvents.
• formulations comprise an initial, low level of a bleach-sensitive antifoam component which is decomposed during storage of the product.
• the composition further comprises a transition metal complexing bleach stabiliser selected from phosphates, phosphonic acids or phosphonates, stannates, carboxylates.
• a transition metal complexing bleach stabiliser selected from phosphates, phosphonic acids or phosphonates, stannates, carboxylates.
• Preferred metal ion complexing agents are selected from dipicolinic acid, ethylene diamine tetra acetic acid (EDTA) and its salts, hydroxy-ethylidene diphosphonic acid (Dequest 2010, RTM) , ethylene diamine tetra (methylene phosphonic acid) (Dequest 2040, RTM) , diethylene triamine penta(methylene phosphonic acid) (Dequest 2060, RTM), amino tri(methylene phosphonic acid) (Dequest 2000, RTM).
• the phosphonic acid derivatives are particularly preferred.
• the level of metal ion complexing agent should fall into the range 0.1-5%.
• Dequest 2010 RTM (ex. Monsanto) organic phosphonate sequestrant for metal ions .
• PAP e-N-N-phthaloyl-amino-peroxycaproic acid (ex. Ausimont) .
• SAS-30 Hostapur 93, (RTM, ex Hoechst) Secondary alkane sulphonate, 93% AD diluted to 30% AD.
• Synperonic A3 (RTM, ex. ICI) alcohol ethoxylate, nonionic surfactant .
• Prifac 5901 (RTM, ex. Unichema) fatty acid.
• Sample formulations were prepared by simple mixing of the components.
• the pH of the formulations was regulated by the addition of 20% w/v NaOH to the required pH as noted in the table.
• the formulation at pH 3.5 is below the pKa of the corresponding imido acid.
• Products were stored at 37°C for three weeks in the dark and the final concentration of PAP was determined by titration under acidic conditions against thiosulphate/KI at 0°C. Products were microscopically examined for the presence of crystals using dark field polarising optical microscopy at 100 fold magnification.
• compositions of the present invention differ only as regards their pH.
• the compositions of the present invention (example 2: pH 5.0) are more stable against both chemical and physical changes than the comparative examples 1 (pH 3.5) and 3 (pH 6.5).
• Tables IB and 1C demonstrate that the pH effect is of particular importance in the compositions of comparative examples 1 and 3 respectively .
• various ratios of surfactant, sulphate and PAP were employed and the products were examined after eight weeks storage.
• examples la-lg and 3a-3h are samples at pH 3.5 and 6.5 respectively with varying ratios of surfactant, sulphate and PAP present.
• the final levels of PAP are indicated on product as absolute values and these final levels of PAP are given as a percentage of the original level (always 2%wt on product) in the '%Final' column.
• the level of total surfactant is fixed at 8%wt, and the surfactant system comprises that of examples 1-3, i.e. a 4:1:1 ratio of SAS to alcohol ethoxylate to fatty acid.
• the level of PAP was 2%, and the level of Dequest 2010 was 0.14.
• the pH of all the examples in Table 2 was around 5. Products were stored at 37°C for eight weeks in the dark and the final concentration of PAP was determined by titration under acidic conditions against thiosulphate/KI at 0°C.
• compositions in examples 4-11 were milky liquids when fresh.
• the composition of example 4 (3% sulphate) showed some slight physical separation after storage.
• the results of Table 2 indicate that the most chemically stable compositions had a weight ratio of sodium sulphate:surfactant of 1:0.8.
• compositions were prepared as described above and buffered at pH's ranging from pH 4.5 to pH 5.5. All compositions initially comprised 10%wt surfactant (4:1:1 ratio as in examples 12-17), 10%wt sodium sulphate, 2% PAP and 0.14% Dequest 2010. The pH was determined again after 15 days storage. The percentage of PAP remaining after 15 days and after 31 days was determined by the method described above.
• compositions having a pH of 4.54 were not stable under the conditions of storage used, almost all of the PAP having decomposed after 31 days of storage.
• Compositions having a pH of 5.0-5.5 showed acceptable storage stability.

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Cited By (16)

Citations (3)

• 1992
  • 1992-12-07 GB GB929225519A patent/GB9225519D0/en active Pending
• 1993
  • 1993-12-01 WO PCT/EP1993/003380 patent/WO1994013776A1/en active Application Filing
  • 1993-12-01 AU AU56506/94A patent/AU5650694A/en not_active Abandoned
  • 1993-12-07 TR TR115093A patent/TR27486A/tr unknown

Patent Citations (3)

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