LIQUID DETERGENT. ISOTROPIC, ALKALINE, CONCENTRATE WITH BLEACHER DESCRIPTION OF THE INVENTION This invention relates to liquid detergents, for washing fabrics, isotropic, alkaline, concentrated with bleach hydrogen peroxide. Liquid fabric washing detergents, isotropic, alkaline, concentrated usually contain a hydrotope to allow a high level of surfactant to be used without the viscosity becoming quite high. Typical hydrotropes are sodium xylene sulfonate, ethanol, and propylene glycol. International Application WO 96/30483 contains such compositions comprising a mixture of nonionic surfactant and anionic surfactant together with a hydrotrope and hydrogen peroxide characterized in that the composition comprises more than 40% total surfactant when concentrated in nonionic or more than 20% total surfactant when concentrated in anionic. A liquid concentrated in peroxide is desirable due to reduced transport and storage costs. A solution to the problem of how to formulate liquid laundry detergents, isotropic, alkaline, concentrated, stable with peroxide has escaped those skilled in the art for many years. Although there are many publications of liquid laundry detergent formulations, isotropic, alkaline, concentrates containing a hydrotrope, there is very little in fact to describe formulations free of hydrotropes. The closest prior art is probably the 15% anionic (secondary alcansulfate) and 3.75% nonionic (ethoxylated primary alcohol (7E0)) composition described in WO96 / 01311. This formulation has a total surfactant level below 20%. Additionally, this composition does not contain additional ingredients such as optical brightener, anti redeposition agent or anti dye transfer which leads to the composition not suitable for use as a fabric washing liquid, isotropic, alkaline detergent, concentrate with peroxide bleach. of hydrogen. The thick peroxide compositions are also known. They contain a thickener system for reinforcing the viscosity when only low levels of surfactant are present. GB 2255507 is typical and describes a composition that contains peroxide, is weighed with less than 10.% surfactant. These compositions are not suitable for use as laundry detergents. These are thickened in order to give the desired result of a squeezable composition that does not run when placed on a vertical surface. Such compositions do not contain a hydrotope and always contain less than 10% total surfactant. A skilled person could not use these thick hdrotopic-free compositions as a starting point for the formulation of a new concentrated fabric washing detergent. It has now been found that the presence of a hydrotope has a large and very undesirable negative effect on the storage stability of liquid alkaline concentrated isotropic fabric washing detergents, in particular it has been found that this is a problem for compositions that they contain high levels of the surfactant. This is a problem for the formulation of concentrated liquid detergents since conventionally such detergents contain hydrotropes. In this concentrated specification it means that the liquid in its undiluted state contains more than 15% and preferably at least 20% and more preferably at least 23% of the total surfactant. According to the present invention there is provided a concentrated alkaline isotropic liquid laundry detergent composition comprising a total surfactant level which includes at least 1% surfactants and additionally comprises at least 0.2% peroxide bleach. hydrogen and an optical brightener, characterized in that the composition is substantially free of hydrotropes. It is preferred that the composition has absolutely no hydrotope added. A small presence of up to 2.5% preferably less than 1.5% and more preferably less than 0.5% of a material which can function as a hydrotrope maybe as a result of one of the ingredients of the composition containing this material as a constituent minor or impurity. Tale ingredients are advantageously avoided since they probably compromise the half-life of the compositionHowever, for a very stable composition, the loss of functioning due to a very small amount of material which can function as a hydrotope can still leave an acceptable average life. It is defined in this specification substantially free of hydrotropes that those materials which can function with hydrotropes in a concentration of less than 2.5%, preferably less than 1.5%, and more preferably less than 0.5% are present. The level of total surfactant is preferably at least 20%, more preferably at least 23%. Preferably the composition comprises anionic and nonionic surfactants. An optical brightener that is compatible with peroxide may be used. An optical brightener having good compatibility with the peroxide bleach is Tinopal CBS-X a derivative of distillerybiphenyl ex Ciba Geigy. Fluorescents based on stilbene can also be used as the optical brightener. According to a second aspect of the invention there is provided a concentrated alkaline isotropic liquid laundry detergent composition comprising a total surfactant level which includes at least 23% of surfactants selected from the group comprising anionic and nonionic surfactants , and additionally comprises at least 0.2% hydrogen peroxide bleach, characterized in that the composition is substantially free of hydrotropes. The composition may also comprise an optical brightener as defined above. When present, the nonionic surfactant preferably comprises more than 5% by weight of the total composition and advantageously the composition includes no more than 5% of surfactants which satisfy the pH criteria when tested according to Test A as described. describes in the present later. More advantageously this comprises no more than 5% surfactants which do not meet the residual peroxide criteria when tested according to Test A as described hereinafter. The surfactant system is preferably a mixture of anionic and nonionic surfactants, although fully nonionic or anionic surfactant systems can be used. The compositions may contain an appropriate reinforcer or have no reinforcer. Among the preferred anionic surfactants are: a) secondary alcansulfonates such as Hostapur SAS 93 an active 93% flake ex. Hoechst or Marión PS65 a n-alcan (C13.17) sodium with low content of sodium sulfate ex. Huís; b) linear alkyl (CXo-? 3) benzenesulfonic acids such as Marion AS3 ex Huís; c) alkyl ether sulfates such as Neopon L = S70, an active 70% sodium salt ex Witco; and d) olefin sulfonates such as Hostapur OS provided as 40% active ex Hoechst. Among the preferred nonionic surfactants are: e) primary ethoxylated alcohols (C? 3-? 5), ethoxylated with 5 to 9 moles of ethylene oxide, preferably 7 triols, such as Synperonic A7 ex ICI / Cargo Fleet. The pH of the composition may be in the range of 7 to 12, and is preferably about 9.5. The peroxide is preferably present as hydrogen peroxide dissolved in an amount by weight in the range of 0.2 to 15% preferably 1 to 8% and more preferably about 5%. The composition may also comprise minor components conventionally found in a liquid detergent composition for difficult dirt. These include perfume, suitably protected enzymes, surfactant preservatives, thickeners, dyes, reinforcing agents, anti-redeposition agents, anti-dye transfer agents - polyvinylpyrrolidone (PVP) which acts both as an anti-redeposition agent and an anti-transfer polymer is preferred. dyes - and other conventional additives. The composition preferably contains sequestrants. Preferred sequestrants are diethylenetriaminepentamethylenephosphonate sodium, sold as Dequest 2066 by Monsanto, either alone or used with 2,2'-dipyridylamine (DPA) or 1,2'-diaminocyclohexyltratrakismethylenephosphonic acid. Other sequestrants for transition metal ions may be used in place of, or in addition to, these preferred sequestrants. In a preferred embodiment, the compositions according to the invention are activated by the use of a bleach activator such as TAED which may be in contact with the composition at the time of use by means of a two compartment administration system. According to a third aspect of the invention, the concentrated alkaline isotropic liquid laundry detergent composition can be used to pre-treat locations of stained or other specific fabrics before the fabric is washed. In this process the stain removal is superior to that which can be obtained from known acidic peroxide compositions and the total operation is increased by the high level of surfactant which is possible in compositions according to the present invention. The use of a concentrated formulation also confers the advantage of lower transport and packaging costs, which is environmentally desirable. The pre-treatment method consists in administering the composition according to one of claims 1 to 11 to a selected area of the product, leaving it in contact with the product for a short treatment period and then washing the product. The treatment period will typically be 1 to 5 minutes, preferably about 2 minutes. Compatibility of surfactants with peroxide The following procedure, referred to as Test A, is used to identify suitable surfactants based on the pH and peroxide stability data. A triple formulation is prepared using 20% w / w (except Marlinat CM20 which is tested at 15% w / w) of the surfactant to be analyzed. After sequestering with Dequest 2066, sufficient hydrogen peroxide is added to give a concentration of 5% w / w peroxide and the pH is adjusted to 9.5 by the addition of a pre-sequestered caustic solution. Details of the surfactants tested in Table 1 are given. Table 1. Tested surfactants
From experience, the following pH and peroxide stability objectives have been derived herein. The residual peroxide is determined by titration with permanganate. A surfactant must pass both the target pH and peroxide. It is possible to use small amounts (<5% preferred) of the surfactant that does not pass all the targets, but this is only practical when the majority of the surfactants exceed the targets by a good margin. As will be seen from the test results in Table 2 it is possible to have satisfactory stability at room temperature even if the stability at elevated temperature is poor. Such surfactants may not be suitable for use in compositions intended to be stored at temperatures in excess of 30 ° C, which is common in hot climates. PH targets: pH25i2 > 9.0 after 12 weeks at 25 ° C pH37i2 > . 7.5 after 12 weeks at 37 ° C pH54 > . 8.0 after 4 weeks at 45 ° C Residual peroxide targets: Per25i2 = 85% after 12 weeks at 25 ° C Per37i2 > . 50% after 12 weeks at 37 ° C Per454 > . 55% after 4 weeks at 45 ° C Table 2 - Results of Test A
* data at 16 weeks ** data at 8 weeks *** data at 4 weeks Below are the surfactants which pass both tests of pH and peroxide stability
(this eliminates surfactants for which the peroxide stability is predominantly due to a decrease in the pH of the composition). A3 and A4 are lower in terms of pH stability because the pH increases in them. In practice, an increase may not be a problem since the benefits of an alkaline composition are retained. Descending order of pH stability: Al > A4 / A3 > N1 / A6 Descending order of peroxide stability: NI > A6 > A3 > A4 > Considering both the pH and the stability of the peroxide, the preferred surfactants are therefore those listed above. Especially preferred for their combination of pH stability and peroxide stability are the secondary alkane sulfonates A3 and A4. In addition to the pH and stability of the peroxide, the phase behavior must also be adequate. Surfactants which pass the pH and peroxide stability criteria are analyzed herein and the following results are obtained in a procedure which is referred to in this specification as Test B. Test B consists of measuring the viscosity of a series. of surfactant solutions with concentrations that increase by increments of 5%. Reference is made to the above concentration which exceeds the viscosity by a value of 1200 cps in this specification as the threshold concentration. The test uses 1200 cps as an approximate upper limit in terms of consumer acceptability. A level at which a particular surfactant is used in a liquid detergent should be below the threshold concentration, preferably at least 5% and more preferably at least 9%. This is to allow inaccurate dosing in the commercial manufacture of a liquid detergent and / or evaporation in storage. The results of the determination of the threshold concentrations for the preferred surfactants are given in Table 3. The numbers in parentheses are the viscosity in centipoise at 25 ° C, 21S "1 of the aqueous solution of the surfactant in the specific concentration. 3 - Results of Test B In addition, the invention will now be described with reference to the following non-limiting examples: Table 4 gives details of the example formulations All the composition data are on a 100% w / w basis. 4
• Additional NaOH is added to make the final pH adjustment. The formulations include PVP (polyvinylpyrrolidone) as an anti redeposition agent and anti-transfer dyes and TINOPAL CBS-X, an optical brightener ex Ciba Geigy. Table 5 to 9 give storage data for the formulations in a range of isothermal storage conditions. Both pH and residual peroxide data are given. Frequently, since the peroxide is more stable under more acidic conditions, reasonable stability to the peroxide is obtained if there is a decrease in the pH of the composition. A drop in pH is not desirable as this reduces detergency and makes it more difficult to activate the peroxide with a bleach activator such as TAED. Table 5 - Example 1
Table 6 - Example 2
Table 8 - Example 4