Aqueous bleach compositions.

0001This invention relates to stable, aqueous, liquid bleach compositions containing a solid, organic peroxy acid, which can be used for effective bleaching of fabrics, hard surfaces or other substrates, either by themselves or in combination with a cleaning detergent composition.

0002Liquid bleaching and detergent compositions have significant advantages over solid compositions as regards both preparation and use. Their preparation does not require cost-increasing shaping steps, such as drying and granulation, and the liquid form contributes to ease of handling, dispensing and solubility, and settles dusting problems.

0003Aqueous, liquid bleach compositions comprising a solid, particulate organic peroxy acid suspended in an acidic aqueous liquid containing a surfactant as known in the art.

0004EP-A-0160342 (UNILEVER) discloses such liquid bleach compositions containing a surfactant and an electrolyte.

0005EP-A-176124 (AKZO) discloses aqueous, liquid bleaching compositions containing a peroxy dicarboxylic acid and an alkyl benzene sulphonate surfactant.

0006EP-A-0201958 (AKZO) discloses aqueous, liquid detergent and bleaching compositions containing a linear alkyl benzene sulphonate surfactant, an ethoxylated fatty alcohol and a peroxydicarboxylic acid.

0007EP-A-0240481 (PROCTER & GAMBLE) discloses aqueous, liquid bleach compositions containing diperoxy acid particles, C₁₁-C₁₃ linear alkyl benzene sulphonate surfactant, magnesium sulphate and water.

0008Conspicuously, all these liquid peroxy acid bleach compositions of the art use alkyl benzene sulphonate as the primary surfactant in the suspending liquid. Alkyl benzene sulphonates as a class are very suitable primary surfactants for structuring liquids capable of suspending solids, because of their great flexibility and independency of formulation changes; they are, however, insufficiently biodegradable. Another drawback of the compositions of the art is that they tend to suffer from instability problems at slightly elevated temperatures. There is thus a continuing need for the development of physically and chemically stable, aqueous, liquid peroxy acid bleaches which are environmentally more acceptable. Though various anionic surfactants are known which are environmentally more acceptable than alkyl benzene sulphonates, they are either less chemically stable or less effective structurants.

0009It has now been found that an improved physically and chemically stable, aqueous, liquid peroxy acid bleach composition can be obtained by using a surfactant mixture conprising a secondary alkane sulphonate and an ethoxylated fatty alcohol in certain weight ratios. Accordingly, the invention provides a stable, aqueous, liquid bleach composition comprising : <ul id="ul0001" list-style="none"><li>(a) from 1.5 to 20% by weight of a solid, particulate, substantially water-insoluble, organic peroxy acid;</li><li>(b) from 2 to 20% by weight of a surfactant mixture consisting of a secondary C₁₀-C₂₀ alkane sulphonate (SAS) and an ethoxylated fatty alcohol (NI) in a weight ratio of from 5:5 to 9:1;</li><li>(c) from 7 to 16% by weight of sodium sulphate, said composition having a pH of from about 2 to about 6 and a viscosity of from about 50 to about 1000 cps. (0.05 PaS to 1.0 PaS) measured at a shear rate of 21 second⁻¹ at 20°C.</li></ul>

0010A preferred composition according to the invention will comprise : <ul id="ul0002" list-style="none"><li>(a) from 4 to 15% by weight of said peroxy acid;</li><li>(b) from 5 to 15% by weight of said surfactant mixture in a weight ratio of from 6:4 to 8:2;</li><li>(c) from 10 to 15% by weight of sodium sulphate; and have a pH of from about 3.0 to 5.0, preferably from 3.5 to 4.5%.</li></ul>

0011A lower pH range of from 2 to 3.5 is of advantage for improved disinfecting and hygiene purposes in the cleaning and bleaching of hard surfaces.

0012The liquid bleach compositions herein contain as bleaching agent a solid, particulate, substantially water-insoluble, organic peroxy acid. By "substantially water-insoluble" is meant here a water-solubility of less than about 1% by weight at ambient temperature. In general, peroxy acids containing at least about 7 carbon atoms are sufficiently insoluble in water for use herein.

0013These materials have the general formula : HO-O-<img file="EP0337516A2_D0001.tif" />-R-Y wherein R is an alkylene or substituted alkylene group containing from 6 to about 20 carbon atoms or a phenylene or substituted phenylene group, and Y is hydrogen, halogen, alkyl, aryl or -<img file="EP0337516A2_D0002.tif" />-OH or -<img file="EP0337516A2_D0003.tif" />-O-OH The organic peroxy acids usable in the present invention can contain either one or two peroxy groups and can be either aliphatic or aromatic. When the organic peroxy acid is aliphatic, the unsubstituted acid has the general formula : HO-O-<img file="EP0337516A2_D0004.tif" />-(CH₂)_n-Y where Y can be, for example, H, CH₃, CH₂Cl, COOH, or COOOH; and n is an integer from 6 to 20.

0014When the organic peroxy acid is aromatic, the unsubstituted acid has the general formula : HO-O-<img file="EP0337516A2_D0005.tif" />-C₆H₄-Y wherein Y is hydrogen, alkyl, alkyl halogen or halogen, or COOH or COOOH.

0015Typical monoperoxy acids useful herein include alkyl peroxy acids, alkenyl peroxy acids and aryl peroxy acids such as : <ul id="ul0003" list-style="none"><li>(i) peroxy benzoic acid and ring-substituted peroxy benzoic acids, e.g. peroxy-alpha-naphthoic acid;</li><li>(ii) aliphatic and substituted aliphatic monoperoxy acids, e.g. peroxy lauric acid and peroxy stearic acid.</li></ul>

0016Typical diperoxy acids useful herein include alkyl diperoxy acids, alkenyl diperoxy acids and aryl diperoxy acids, such as <ul id="ul0004" list-style="none"><li>iii) 1,12-diperoxy dodecane dioic acid;</li><li>iv) 1,9-diperoxy azelaic acid;</li><li>v) diperoxy brassylic acid; diperoxy sebasic acid and diperoxy isophthalic acid;</li><li>vi) 2-decyl diperoxy butane-1,4-dioic acid;</li><li>vii) 4,4¹-sulphonyl bisperoxy benzoic acid.</li></ul>

0017A particularly preferred peroxy acid for use herein is 1,12-diperoxy dodecane dioic acid (DPDA).

0018The particle size of the peroxy acid used in the present invention is not crucial and can be from about 0.5 to 1000 microns, though a small particle size, such as e.g. from 0.5 to 15 microns, is favoured for laundering applications.

0019The secondary alkane sulphonates (SAS) used herein are n-alkane sulphonates with the formula : <chemistry id="chem0001" num="0001"><img file="EP0337516A2_D0006.tif" /></chemistry> wherein R and R¹ are alkyl groups having together 9-19 carbon atoms; and M is an alkali metal, particularly sodium or potassium. They can be obtained by sulphoxidation of n-paraffifns of the appropriate chain length and are available from Hoechst under the trade-mark Hostapur SAS of various grades, e.g. Hosapur SAS 30, 60 and 93.

0020A preferred SAS material is sodium secondary C₁₂-C₁₈ alkane sulphonate, particularly C₁₃-C₁₇ secondary alkane sulphonate.

0021The NI material used herein is preferably an ethoxylated fatty alcohol having a Hydrophilic-Lipophilic Balance (HLB) or not more than 10.5, preferably an HLB of between 6 and 10, particularly from 8-8.5.

0022An example of suitable NI material is commercially available under the name of Synperonic A3 supplied by ICI (Synperonic is a trade-mark), which is a fatty alcohol-3 ethylene oxide having an HLB of 8.3.

0023The composition of the invention can contain, and preferably does, hydrogen peroxide in an amount of approximatively 1-10% by weight of H₂O₂, particularly about 5% by weight, which is surprisingly stable in the composition. Hydrogen peroxide provides improvement of bleach performance at higher temperatures. When hydrogen peroxide is present, the level of surface-active agent should preferably be not in excess of 10% by weight.

0024Since metal ion impurities (e.g. copper and iron) can catalyze peroxy acid decomposition in the liquid bleaching composition, certain metal ion complexing agents can be incorporated to remove metal ion contaminants from the composition. It is thus desirable to include a metal complexing agent in the composition. Such agents are preferably present in an amount ranging from 0.005% to about 1.0% by weight.

0025Examples of useful metal ion complexing agents include dipicolinic acid, with or without a synergistic amount of a water-soluble phosphate salt; dipicolinic acid N-­oxide; picolinic acid, ethylene diamine tetraacetic acid (EDTA) and its salts; various organic phosphonic acids or phosphonates such as ethylene diamine tetra-­(methylene phosphonic acid) and diethylene triamine penta-(methylene phosphonic acid).

0026Other metal complexing agents known in the art may also be useful, the effectiveness of which may depend strongly on the pH of the final formulation. Generally, and for most purposes, levels of metal ion complexing agents in the range of from about 10-1000 ppm are already effective for removing the metal ion contaminants.

0027In addition to the components discussed above, the liquid bleaching compositions of the invention may also contain certain optical ingredients in minor amounts, depending on the purpose of use. Typical examples of optional ingredients are suds-controlling agents, fluorescers, perfumes, colouring agents, abrasives, hydrotropes and antioxidants. Also other surfactants may desirably be incorporated in minor amounts to the primary surfactants. However, any such optional ingredient may be incorporated provided that its presence in the composition does not significantly reduce the chemical and physical stability of the peroxy acid in the suspending system.

Example I

0028The following composition was prepared by suspending DPDA in the aqueous surfactant liquid. <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="left"><u style="single">Components</u></entry><entry namest="col2" nameend="col2" align="center"><u style="single">% by weight</u></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">1,12-diperoxy dodecane dioic acid (DPDA)</entry><entry namest="col2" nameend="col2" align="right">10.0</entry></row><row><entry namest="col1" nameend="col1" align="left">Secondary C₁₃-C₁₇ alkane sulphonate (SAS)</entry><entry namest="col2" nameend="col2" align="right">5.1</entry></row><row><entry namest="col1" nameend="col1" align="left">Fatty alcohol-3 ethylene oxide (Synperonic A3)®</entry><entry namest="col2" nameend="col2" align="right">0.9</entry></row><row><entry namest="col1" nameend="col1" align="left">Sodium sulphate</entry><entry namest="col2" nameend="col2" align="right">10.0</entry></row><row><entry namest="col1" nameend="col1" align="left">Ethylene diamine tetra (methylene phosphonic acid)</entry><entry namest="col2" nameend="col2" align="right">0.04</entry></row><row><entry namest="col1" nameend="col1" align="left">Water</entry><entry namest="col2" nameend="col2" align="right">balance to 100%</entry></row><row><entry namest="col1" nameend="col2" align="justify">The pH of this formulation was adjusted to 4.5.</entry></row><row rowsep="1"><entry namest="col1" nameend="col2" align="justify">Viscosity = 0.450 PaS.</entry></row></tbody></tgroup></table></tables>

0029The liquid was easily pourable and showed excellent stability upon storage, both physically and chemically.

Example II

0030The following composition was equally easily pourable and of excellent stability upon storage, both physically and chemically. <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="left"><u style="single">Components</u></entry><entry namest="col2" nameend="col2" align="center"><u style="single">% by weight</u></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">DPDA</entry><entry namest="col2" nameend="col2" align="right">10</entry></row><row><entry namest="col1" nameend="col1" align="left">SAS</entry><entry namest="col2" nameend="col2" align="right">5.1</entry></row><row><entry namest="col1" nameend="col1" align="left">Synperonic A3</entry><entry namest="col2" nameend="col2" align="right">0.9</entry></row><row><entry namest="col1" nameend="col1" align="left">Hydrogen peroxide (H₂O₂)</entry><entry namest="col2" nameend="col2" align="right">5.0</entry></row><row><entry namest="col1" nameend="col1" align="left">Silicone oil (DB 100 ex Dow Corning)</entry><entry namest="col2" nameend="col2" align="right">0.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Ethylene diamine tetra (methylene phosphonic acid)</entry><entry namest="col2" nameend="col2" align="right">0.05</entry></row><row><entry namest="col1" nameend="col1" align="left">Sodium sulphate</entry><entry namest="col2" nameend="col2" align="right">10.0</entry></row><row><entry namest="col1" nameend="col1" align="left">Water</entry><entry namest="col2" nameend="col2" align="right">balance to 100%</entry></row><row><entry namest="col1" nameend="col2" align="justify">pH adjusted to 4.5 and 3.5</entry></row><row rowsep="1"><entry namest="col1" nameend="col2" align="justify">Viscosity = 0.450 PaS</entry></row></tbody></tgroup></table></tables>

0031The product having a pH 3.5 can advantageously be used as disinfectant in the cleaning of e.g. hard surfaces.