Powdered surfactant compositions comprising branched alcohol sulfates and inorganic salts

Abstract

The subject matter of the present invention relates to a powdered surfactant composition comprising branched C12 / C13 alcohol sulfates and inorganic salts. The powdered surfactant composition can be used in solid toilet block formulations further comprising additional inorganic salts. The invention further relates to a method for producing the solid toilet block formulations.

Description

[0001] The present invention relates to powdered surfactant compositions comprising branched alcohol sulfates and inorganic salts. Further, the invention relates to a process to produce toilet block formulations based on the powdered surfactant composition, the use of the powdered surfactant composition in a solid toilet block formulations for cleaning a toilet and toilet block formulations comprising the powdered surfactant composition and inorganic salts.BACKGROUND OF THE INVENTION AND DISCUSSION OF THE PRIOR ART

[0002] Due to rising demand from end users, toilet block formulations are of interest in the homecare industry. The commonly used powders used in toilet block formulations are based on linear alkylbenzene sulfonates (LAS) and / or alpha-olefin sulfonates (AOS). However, in view of sustainability and eco-toxicology sulfonate-based products are not ideal, specifically because they do not show good biodegradability under anaerobic conditions. Typical toilet block formulations, including solid toilet rim block formulations, can be produced in a variety of forms and types, containing one or more anionic surfactants, perfume, colourants, (chlorine) bleach, and other components. The content of typical formulations generally found in the market is shown in Table 1. Table 1: Typical formulation approach for solid toilet rim blocks, based on linear alkylbenzene sulfonates (LAS) and / or alpha olefin sulfonates (AOS) (* EO = ethylene oxide unit).Raw Materials Range (wt%) Sodium sulfate10 - 60LAS / AOS5 - 40C 16-18 alcohol with 20-30 EO* (e.g. ceteareth-25)0 - 10Paraffins0 - 10Polyethylene glycol 4000 - 80000 - 20Perfume0.1 - 10Bleach / Oxidising agents0 - 5Solvents1Colourants1 - 2

[0003] The main task of the anionic surfactant is to clean the toilet bowl and to achieve a high and stable foam during flushing. For solid formulations, anionic surfactants that can be powdered in an easy-to-manage and affordable process, e.g. by drum-drying, spray-drying or other processes, must be made available. Due to the particles shape so obtained and thus the processability, drum-dried powders are preferred for this application. In the market, linear alkylbenzene sulfonate-powders, based on sodium salts of C 10-13 alkylbenzene sulfonic acids and (alpha-)olefin sulfonates, commonly based on C 14-16 alkyl chains, are used as they are widely available in large volumes with an excellent price-performance ratio. The active content of such powders is typically between 80 and 90 wt.%.

[0004] One alternative to the sulfonates mentioned above, are alcohol sulfates (AS), typically obtained from alcohols derived from natural plant material. Such alcohols are linear alcohols. Linear alcohol sulfates, however, show disadvantages when used in toilet block formulations. Such disadvantages include low cold-water solubility, little hard water tolerance, and their processability, which is often compromised when forming solid toilet blocks.

[0005] The use of anionic surfactants in solid toilet block formulations is known, mostly as part of complex mixtures. In this context, US5939372 A describes, for instance, the use of a combination of fatty alcohol sulfates, fatty alcohol ether sulfates, alkyl or alkenyl oligoglycosides and / or fatty acid N-alkyl polyhydroxyalkyl amides.

[0006] It is known that surfactants with linear C 12-18 , C 16-18 or C 12-14 carbon-chains can be used in toilet block formulations. These compounds can be powdered using typical methods without addition of inorganic salts and overcome processability issues such as stickiness, especially in warm and humid regions. One problem when using toilet block formulations with these types of compounds is, however, their relatively high Krafft-point (temperature), leading to insufficient water solubility at low temperatures. Depending on sources, region and climate, the apparent water temperature can vary between 5°C and 20°C. Thus, for many of the above anionic surfactants, solubility problems, as well as low foaming, can be observed. Additionally, alcohol sulfates based on linear C 12-14 , C 12-18 or C 16-18 alcohol are sensitive towards calcium and magnesium ions (hard water) and tend to form sparingly soluble Ca- or Mg-alcohol sulfates that precipitate or crystallize in aqueous media. Precipitated surfactants are not "active" for cleaning and tend to suppress foam forming.

[0007] There is a rising demand to use raw materials with an appropriate eco-toxicity profile and biodegradability, and the need for new raw materials - specifically anionic surfactants that can be dried to free-flowing powders, is becoming increasingly important.OBJECT OF THE PRESENT INVENTION

[0008] It is one object of this invention to provide powdered surfactant compositions for use in solid toilet block formulations, where the formulations show enhanced solubility, stability, and foaming and a lack of precipitation. The invention's further object is to provide an enhanced manufacturing process for solid toilet block formulations, incorporating such powdered surfactant compositions.SUMMARY OF THE INVENTION

[0009] The present invention relates to powdered surfactant compositions, hereinafter also in short "surfactant compositions" or "surfactant composition comprising branched alcohol sulfates as anionic surfactants in combination with inorganic salts, in particular for use in solid toilet block formulations.

[0010] It was surprisingly found that simple surfactant compositions comprising branched alcohol sulfates with a specific carbon-chain length display significantly improved cold-water solubility, a very low tendency for precipitation and better hard-water tolerance when compared to state-of-the-art products. High foaming performance was also observed. Furthermore, it was found that by branched alcohol sulfates according to the invention, the processability of the premixes for making solid toilet blocks was significantly improved. Compared to LAS, the presently claimed surfactant compositions also have an enhanced biodegradability, in particular anaerobic biodegradability. The powdered surfactant compositions comprise anaerobically biodegradable alcohol sulfates and display enhanced foaming properties, excellent cold-water solubility and hard water tolerance, resulting in the avoidance of precipitation when used in toilet bowl applications.

[0011] The alcohol sulfates i) comprised in the surfactant compositions according to the invention have the following structure [I]:         R - O - SO 3 X     [I] wherein R = is an alkyl group having 12 or 13 atoms, wherein the average degree of branching in R is from 40 to 96 %; X = is an alkali metal, ammonium or C2- or C3-alkanolammonium ion, preferably sodium.

[0012] In addition, the surfactant composition also comprises one or more inorganic salts ii). The weight ratio of the inorganic salts ii) to alkanol sulfates i) is from 3 : 97 to 20 : 80; and at least 90 wt.%, preferably at least 95 wt.% and more preferably at least 98 wt.% of all anionic surfactants contained in the surfactant composition have structure I.

[0013] Preferably greater than 50 wt.%, more preferably greater than 80 wt.% of the surfactant compositions are alcohol sulfonates of structure [I].

[0014] Preferably, the surfactant composition does not contain alkylbenzene sulfonates and / or alpha-olefin sulfonates.

[0015] The surfactant composition preferably is further free from one or more of alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids; and alpha-olefin sulfonates.

[0016] According to one embodiment, the surfactant composition comprises alcohol sulfates according to structure [I], wherein the branching of R is mainly mono-branched, preferably mainly methyl branched and most preferably mainly methyl-branched on carbon 2 of the alkyl group. "mainly" means more than 60 mol% of all branched alcohol sulfates.

[0017] The alkyl group of the alcohol sulfates of structure [I] preferably have an average degree of branching of 40 to 60 wt%. This means that on average 40 to 60 wt% of all of the alcohol sulfates contained in the surfactant composition have branching. The average degree of branching is the number of all branches in the alcohol sulfates divided by the number of alcohol groups and this provided in percentage. As an example, if there are four molecules of alcohol sulfates and three of the alcohol groups are linear (no branches) and one has two branches, the degree of branching alcohol sulfates of structure [I] is 50 % (2 branches / 4 molecules).

[0018] The inorganic salt of the surfactant composition is selected from the group of sulfates, carbonates, citrates, chlorides and other halogenides, sulphides, oxides, nitrates, acetates, formiates, phosphates, with the counterion selected from the group of Na +< , K +< , NH 4 +< , Ca 2+< , Mg 2+< , Fe 2+< , Al 3+< , C2- to C3- alkanol-ammonium- and C1- to C3-alkylammonium- ions.

[0019] In a specific embodiment of the invention, the inorganic salt of the surfactant composition is or comprises sodium sulfate.

[0020] The surfactant composition may further comprise, besides the inorganic salts, one or more members selected from the group of alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, and / or salts of fatty acids.

[0021] The surfactant composition preferably does not contain alkylbenzene sulfonates und / or and alpha-olefin sulfonates.

[0022] A further embodiment of the invention is the use of the powdered surfactant composition in solid toilet block formulations.

[0023] In a typical embodiment of the use of the surfactant composition the weight ratio of the surfactant composition to the remainder of the solid toilet block formulation is from 10:90 to 40:60.

[0024] According to a further embodiment of the use of the powdered surfactant composition with in a solid toilet block formulation, the toilet block formulation is free from alkylbenzene sulfonates group of inorganic salts,

[0025] The solid toilet block formulation may comprise alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids; and alpha-olefin sulfonates.

[0026] The method for producing the solid toilet block formulations includes a first step of providing a powdered surfactant composition comprising at least one anionic surfactant and an inorganic salt. The surfactant composition is subsequently mixed with one or more components selected from the group of further inorganic salts, alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids.

[0027] The weight ratio of the surfactant composition to the remainder of the toilet block formulation is from 10:90 to 60:40, more preferably from 15:85 to 50:50 and most preferably from 20:80 to 40:60. The solid toilet block formulation is optionally free from alkylbenzene sulfonates and alpha-olefin sulfonates.

[0028] The solid toilet block formulation is finally subjected to a molding procedure to obtained a solid shaped article.DETAILED DESCRIPTION

[0029] The powdered surfactant composition of the current invention comprises anionic surfactants based on branched alcohol sulfates, together with inorganic salts, for application in solid toilet block formulations.

[0030] The invention is further described with reference to the figures: Figure 1: Comparison of foaming properties of different anionic surfactants (1 g / l solutions) in hard water (20 °dH, °dH = German degree of hardness of water) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15 s stirring. Figure 2: Comparison of foaming properties of different alcohol sulfates with variations in carbon-chain length and branching degree (1 g / l solutions) in hard water (20 °dH) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15s stirring. Figure 3: Foam profiles of toilet block formulations with different anionic surfactants in 20 °dH water at 10°C. Materials Used:

[0031] The following anionic surfactant were used to demonstrate the efficiency of powdered surfactant composition according to the invention, in comparison to state-of-the-art surfactants as used in conventional powdered surfactant compositions: The anionic surfactant used all were alcohol sulfates based on the general formula:         R-O-SO 3 -X

[0032] With R = alkyl carbon chain and X = Na +< . Table 2: Surfactant used to demonstrate efficiency comprising sodium sulfate as the inorganic saltSurfactants used TRADE NAME ANIONIC SURFACTANT NATURE OF R-GROUP SAFOL 23 Sulfate (PBAS1) Partially branched alcohol sulfateC 12-13 carbon chain; 50 wt% branching (methyl and other branching on any C-atom)R - O - SO 3 -NaLIAL123 Sulfate (PBAS2) Partially branched alcohol sulfateC 12-13 carbon chain; 40 - 60 wt% branching (mono-methyl branched, mostly on C2 atom)R - O - SO 3 -NaISALCHEM 123 Sulfate (FBAS3) Fully branched alcohol sulfateC 12-13 carbon chain; 90 - 95 wt% branching (mono-methyl branched, mostly on C2 atom)R - O - SO 3 -NaComparative Compositions C 12-14 fatty alcohol sulfate (C 1214 FAS) sodium saltLinear fatty alcohol sulfateC 12-14 carbon chain; linear, derived from palm kern oilR - O - SO 3 -NaMARLINAT 242 / 70 RSPO-MB (SLES) sodium laureth ether sulfateLinear alkyl ether sulfate R - O - EO 1-3 -SO 3 Na with EO = ethylene oxideC 12-14 carbon chain; linear(LAS-Na) MARLON ATFLinear alkylbenzene sulfonic acid, sodium saltC 10-13 carbon chain; linearNACOL 10 FAS (C 10 FAS) Linear fatty alcohol sulfateC 10 carbon chain; linear, < 5 wt% branchedR - O - SO 3 -NaLIAL145 Sulfate (C 1415 PBAS) Partially branched alcohol sulfateC 14-15 carbon chain; 40 - 60 wt% branching (mono-methyl branched, mostly on the C2 atom)R - O - SO 3 -Na EXPERIMENTAL SECTIONPreparation of the alcohol sulfates:

[0033] Alcohol sulfates can be produced in different ways that are commonly known to a person skilled in the art. A well-known procedure is the sulfation of alcohols with sulfur trioxide in a falling film tube reactor (Kosswig, Kurt (2000). "Surfactants". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH). It is also possible to sulfate alcohols in a batch process with oleum or chlorosulfuric acid (Eduard Smulders et al. "Laundry Detergents" in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim; Klaus Noweck et al, "Fatty Alcohols" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim). All alcohol sulfates were produced using a falling film reactor. The alcohols were treated with sulfur trioxide / air mixture with subsequent neutralization with NaOH-solution. The addition of the NaOH-solution resulted in up to 0.5 wt.% additional salts.

[0034] The following experiments were carried out to demonstrate the advantages of surfactants as used in the powdered surfactant composition of the invention.Water solubility / stability in demineralised water

[0035] The appearance of the compositions dissolved in demineralised water at room temperature comprising the branched alcohol sulfates PBAS1 only was visually compared to the linear C 12-14 fatty alcohol sulfate C 1214 FAS,) at different concentrations of 1 g / l, 5 g / l, 10 g / l (all surfactant actives) in demineralised water, after storage for 72 h at 7 °C. Table 3: Appearance of a partially branched alcohol sulfate PBAS1 and linear C12-14 fatty alcohol sulfate (C1214 FAS) at different concentrations in demineralised water after 72 h at 7 °C .Surfactant type1 g / l5 g / l10 g / lPBAS 1ClearClearClearC12-14 FASSlightly turbid / sedimentationTurbid / sedimentationTurbid / sedimentation

[0036] PBAS1 provided a water-clear solutions at concentrations from 1 to 10 g / l, after 72 h stored at 7°C. Linear C 12-14 fatty alcohol sulfate (C 12-14 FAS), however, crystallized in typical shapes, such as needles or plates already at concentrations of 1 g / l, with an increasing amount of crystals at 5 g / l and 10 g / l causing a turbid / milky phase for more of 50% at 5 g / l and more of 75% (at 10 g / l) of the filling hight.

[0037] Partially branched alcohol sulfates different in branching were used for the comparison. The cold-water solubility test was done with PBAS2 at lower temperatures (4°C). Table 4: Appearances of PBAS1 and branched alcohol type 2 (PBAS2) at different concentrations in demineralised water, after 72 h at 4 C.Surfactant type1 g / l5 g / l10 g / lPBAS 1ClearClearSlightly precipitatedPBAS 2ClearClearSlightly precipitated

[0038] In Table 4, PBAS1 and PBAS2 were mixed at three different concentrations (1, 5 and 10 g / l alkanol sulfates according to structure [1] (without the inorganic salts) in demineralised water, stored for 2 days at 4°C). Excellent cold-water solubilities are demonstrated under these conditions, with only slight precipitation observed at the bottom of the glass containers and no turbid / milky phase.

[0039] The effect of longer carbon-chain length for R and of variations in the branching on solubility at low temperatures was demonstrated in the following experiment. Table 5: Appearances of FBAS3 (1), C 1415 PBAS (2) and C 10 FAS (3) at different concentrations in demineralised water, after 72 h at 4 C. (a: 1 g / l, b: 5 g / l and c: 10 g / l)Surfactant type1 g / l5 g / l10 g / lFBAS 3ClearClearClearC1415 PBASSlightly precipitatedTurbid / precipitatedTurbid / precipitatedC10 FASClearClearPrecipitated

[0040] Table 5 shows that a fully branched C 12-13 AS (FBAS3) demonstrated good solubility at 4°C, while a branched C 14-15 AS (C 1415 PBAS) precipitated and resulted in sedimentation. A linear C 10 AS (C 10 FAS) showed good solubility but precipitated at 10 g / l.

[0041] Although toilet temperatures of 4°C are unlikely for common households in Europe, the test results above demonstrate the advantage the claimed alcohol sulfates have at low temperatures. However, the suitability of the alcohol sulfates is not only a matter of their cold-water solubility but also depends on other factors such as foam formation and hard-water tolerance.Foaming behaviour

[0042] Foaming is an important property of toilet block formulations. In household applications tap water is used that generally ranges from soft to hard water. The surfactants used should, therefore, cause fast foam formation and high foaming across a wide range of conditions.

[0043] A SITA Foam Tester R-2000 was used to evaluate the foaming behaviour. All surfactants were dissolved at concentrations of 1 g / l (active matter) in water with 20 °dH [equivalent to 356 ppm CaCO 3 ]. Tests were carried out at 20°C. Foam volume values were measured after 15 s of stirring at 1100 rpm. For comparison, a commercially available C 12-14 -based ether sulfate (sodium laureth ether sulfate (SLES), MARLINAT 242 / 70 RSPO-MB) was used, which does not show precipitation in hard water.

[0044] Figure 1 shows the different foaming properties of the tested surfactants in hard water. The commercially available product, SLES, demonstrated a typical fast and high foaming behaviour using the described test method. LAS (sodium salts) are known to be sensitive to water hardness and show moderate foaming.

[0045] C 12-14 fatty alcohol sulfates (C 1214 FAS) displayed significantly lower foaming, which was not caused by solubility problems at low temperatures but rather resulted from the formation of insoluble Ca- / Mg- adducts. Surprisingly, the partly branched C 12-13 AS (PBAS1) showed similar high foaming behaviour compared to SLES. The velocity of foam formation was not as rapid as for SLES, but the anionic surfactant demonstrated a surprisingly good foam profile under these conditions.

[0046] To determine if variations in carbon-chain length or in the branching degree will have a positive or negative influence on the foaming behaviour in hard water (20°dH) at 20°C, the following sodium salts of the alcohol sulfates, were tested (see Table 6): Table 6: Variation in surfactant carbon-chain lengthC-chain cut Branching Abbreviation C 12-13 50 %PBAS1C 12-13 90-95 %FBAS3C 10 <5 %C 10 FASC 14-15 40-60 %C 1415 PBAS

[0047] The foam profile was again determined using the same method and parameters described before (see Figure 2).

[0048] Figure 2 shows the foam formation for the different alcohol sulfates of Table 6. In hard water (20 °dH), FBAS3 showed a slightly faster foam formation compared to PBAS1. The longer carbon-chain length alcohol sulfate C 14-15 PBAS showed foam foam . Shorter carbon-chain length surfactants, in this case C 10 FAS, showed some foam formation (but not as high as the C 12-13 types).Process to manufacture powdered alcohol sulfates / toilet block formulations

[0049] For the drying process of the liquid, branched alcohol sulfate slurry to the corresponding powder, a drum dryer is preferred. Spray-drying and other commonly known technologies are, however, feasible as well. The choice of drying techniques will determine further properties like morphology, bulk density and furthermore dissolving properties or capability for further processing. The specific drying technique chosen is therefore one factor to determine its suitability for the subsequent application and formulation type. The use of different inorganic salts, oxides or organic additives can adjust different properties like stickiness, flowability etc. as demanded, and can be suitably adjusted by the person skilled in the art.

[0050] In general, sodium salts of partially branched alcohol sulfates with active matters between 30 and 45 wt% or between 60 and 75 wt% can be mixed with inorganic salts to determine the properties of the resulting powder. According to one embodiment sodium citrate, sodium sulfate and / or sodium carbonate can be used alone or in combination. Sodium salts are generally preferred.

[0051] In the following examples, the premixes (slurries) were made by using PBAS1 with 40% active matter. The composition of such a premix is given in Table 7. Table 7: Slurry as premix for drum-drying to powderRaw material Slurry mix (g) Slurry mix (actives) (wt%) PBAS1 (40 wt% surfactant)10038sodium sulfate contributed by PBAS10.5Sodium sulfate33.5Sodium citrate22Sodium carbonate11Water (additional)-55.5Sum106100

[0052] The homogeneously stirred slurry is deposited between the two drums of a drum dryer. The heated rotating drums dry the slurry to a brittle mass which is thereafter removed by knives and transported to a mill to break the aggregates.

[0053] Typical concentration ranges of the components of the powder for making the solid toilet block formulation are shown in Table 8 after vaporizing the water to a water content of max. 2 wt% remaining. Table 8: Powdered branched alcohol sulfate compositionRaw material Actives (wt%) PBAS175-93Sodium sulfate2-8Sodium citrate2-8Sodium carbonate0-6Water0-2

[0054] Typically, the sum of the inorganic salts is between 3 and 15 wt% of the powdered surfactant composition. The resulting powder has a white to slightly yellowish appearance, and a bulk densities of 350 to 550 g / l.

[0055] In order to test the use of differently branched alcohol sulfates in toilet block formulations, the following formulations were used where the liquid components have to be adjusted to soft mixtures easily moldable. The consistency of the mixture is important for the shaping process in order to achieve the desired shape (see Table 9). Table 9: Test formulations for toilet blocksRaw material Test formulation (g) Sodium sulfate60PBAS 128C 1618 -ethoxylated (25 EO) alcohol)5Monopropylene glycol2Demineralised water2

[0056] All formulations were mixed to achieve a homogeneous soft dough-like substance within 30 min, using a lab kneader. In the test formulation, the liquid components were varied, starting with 2 ml total liquids, to get a soft mixture / "dough", which was manually formed into the shape of balls. The shaped balls were formed directly after the mixing process and were visually tested to observe whether closed balls without cracks were formed. This property is of importance for processing of the toilet blocks in an industrial manufacturing process: Table 10: Experiments to achieve sufficient softness for shaping / processing.Raw material A (comparative) B (comparative) C (inventive) wt% Sodium sulfate62.96061.9LAS-NA powder, 88% actives29.300C 1214 FAS0280PBAS10028.9C 16-18 -25 EO EMULDAC AS25 (linear ethoxylated alcohol)5.255.2Monopropylene glycol1.33.52Demineralised water1.33.52TOTALS:100100100

[0057] Formulation A from Table 10 contained LAS-Na powder, required the lowest amounts of liquid components (monopropylene glycol + water = 2.6 wt%) to be added, in order to achieve sufficient processability. This was followed by the branched alcohol sulfate (Formulation C = 4 wt% liquid components). For Formulation B (containing C 1214 FAS) the mass was very hard to form, and the addition of liquid components up to 7 wt% was required.

[0058] Compositions A and C with branched alcohol sulfate showed clear advantages when compared to composition B, which comprised linear fatty alcohol sulfates with regard to the processability of the mixtures. This property is important to avoid problems with automatic shaping devices in the production of shaped solid toilet block formulations.

[0059] To test the foaming behaviour of the toilet block formulations comprising PBAS 1 under conditions present in a toilet, it was assumed that the water temperature is 10°C, using synthetic hard water with 20°dH. The tests were carried in a SITA-Foam Tester R-2000 under the same conditions as for Figures 1 and 2 (except for the temperature being 10°C).

[0060] Figure 3 shows the effect of hard water and low temperature on the foamability of different toilet block formulations. Formulation B (C 1214 FAS-based) did not display favourable foaming behaviour. Due to its low hard-water tolerance, the resulting solution was turbid and foaming was depressed.

[0061] Formulation A based on LAS-Na showed better performance, but foaming was still limited to a maximum value of 150 ml. Formulation C, based on PBAS1, displayed superior foaming behaviour.Stability tests

[0062] Apart from the challenge of obtaining good foaming when used in hard- or cold-water conditions, precipitation of the anionic surfactants in the toilet bowl must be kept at a minimum. Tests were carried out storing different 1 wt% actives solutions (base formulations) (see Table 11) in tap water (12 °dH) for 72 h at 10°C and 23°C. The results are shown in Table 11 below. Table 11: Appearance of solutions of different surfactants in tap water (12 °dH) at 23 °C and 10 °C, stored for 72 h.Surfactant typeAppearance at 23°CAppearance at 10 °CLASClearClearC12-14 FASClearPrecipitation / turbidPBAS 1ClearClear

[0063] No precipitation occurred and at 23°C water-clear solutions were obtained for all base formulations.

[0064] At 10°C, the base formulation with C 1214 FAS showed precipitation and sedimentation of the anionic surfactant. The formulation based on LAS and PBAS1 did not show significant precipitation under these conditions at 10°C.

Examples

Embodiment Construction

[0029]The powdered surfactant composition of the current invention comprises anionic surfactants based on branched alcohol sulfates, together with inorganic salts, for application in solid toilet block formulations.

[0030]The invention is further described with reference to the figures:

Figure 1: Comparison of foaming properties of different anionic surfactants (1 g / l solutions) in hard water (20 °dH, °dH = German degree of hardness of water) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15 s stirring. Figure 2: Comparison of foaming properties of different alcohol sulfates with variations in carbon-chain length and branching degree (1 g / l solutions) in hard water (20 °dH) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15s stirring. Figure 3: Foam profiles of toilet block formulations with different anionic surfactants in 20 °dH water at 10°C.

Materials Used:

[0031]The following anionic surfactant were used to demonstrate the efficiency of powdered surfac...

[0001] The present invention relates to powdered surfactant compositions comprising branched alcohol sulfates and inorganic salts. Further, the invention relates to a process to produce toilet block formulations based on the powdered surfactant composition, the use of the powdered surfactant composition in a solid toilet block formulations for cleaning a toilet and toilet block formulations comprising the powdered surfactant composition and inorganic salts.BACKGROUND OF THE INVENTION AND DISCUSSION OF THE PRIOR ART

[0002] Due to rising demand from end users, toilet block formulations are of interest in the homecare industry. The commonly used powders used in toilet block formulations are based on linear alkylbenzene sulfonates (LAS) and / or alpha-olefin sulfonates (AOS). However, in view of sustainability and eco-toxicology sulfonate-based products are not ideal, specifically because they do not show good biodegradability under anaerobic conditions. Typical toilet block formulations, including solid toilet rim block formulations, can be produced in a variety of forms and types, containing one or more anionic surfactants, perfume, colourants, (chlorine) bleach, and other components. The content of typical formulations generally found in the market is shown in Table 1. Table 1: Typical formulation approach for solid toilet rim blocks, based on linear alkylbenzene sulfonates (LAS) and / or alpha olefin sulfonates (AOS) (* EO = ethylene oxide unit).Raw Materials Range (wt%) Sodium sulfate10 - 60LAS / AOS5 - 40C 16-18 alcohol with 20-30 EO* (e.g. ceteareth-25)0 - 10Paraffins0 - 10Polyethylene glycol 4000 - 80000 - 20Perfume0.1 - 10Bleach / Oxidising agents0 - 5Solvents1Colourants1 - 2

[0003] The main task of the anionic surfactant is to clean the toilet bowl and to achieve a high and stable foam during flushing. For solid formulations, anionic surfactants that can be powdered in an easy-to-manage and affordable process, e.g. by drum-drying, spray-drying or other processes, must be made available. Due to the particles shape so obtained and thus the processability, drum-dried powders are preferred for this application. In the market, linear alkylbenzene sulfonate-powders, based on sodium salts of C 10-13 alkylbenzene sulfonic acids and (alpha-)olefin sulfonates, commonly based on C 14-16 alkyl chains, are used as they are widely available in large volumes with an excellent price-performance ratio. The active content of such powders is typically between 80 and 90 wt.%.

[0004] One alternative to the sulfonates mentioned above, are alcohol sulfates (AS), typically obtained from alcohols derived from natural plant material. Such alcohols are linear alcohols. Linear alcohol sulfates, however, show disadvantages when used in toilet block formulations. Such disadvantages include low cold-water solubility, little hard water tolerance, and their processability, which is often compromised when forming solid toilet blocks.

[0005] The use of anionic surfactants in solid toilet block formulations is known, mostly as part of complex mixtures. In this context, US5939372 A describes, for instance, the use of a combination of fatty alcohol sulfates, fatty alcohol ether sulfates, alkyl or alkenyl oligoglycosides and / or fatty acid N-alkyl polyhydroxyalkyl amides.

[0006] It is known that surfactants with linear C 12-18 , C 16-18 or C 12-14 carbon-chains can be used in toilet block formulations. These compounds can be powdered using typical methods without addition of inorganic salts and overcome processability issues such as stickiness, especially in warm and humid regions. One problem when using toilet block formulations with these types of compounds is, however, their relatively high Krafft-point (temperature), leading to insufficient water solubility at low temperatures. Depending on sources, region and climate, the apparent water temperature can vary between 5°C and 20°C. Thus, for many of the above anionic surfactants, solubility problems, as well as low foaming, can be observed. Additionally, alcohol sulfates based on linear C 12-14 , C 12-18 or C 16-18 alcohol are sensitive towards calcium and magnesium ions (hard water) and tend to form sparingly soluble Ca- or Mg-alcohol sulfates that precipitate or crystallize in aqueous media. Precipitated surfactants are not "active" for cleaning and tend to suppress foam forming.

[0007] There is a rising demand to use raw materials with an appropriate eco-toxicity profile and biodegradability, and the need for new raw materials - specifically anionic surfactants that can be dried to free-flowing powders, is becoming increasingly important.OBJECT OF THE PRESENT INVENTION

[0008] It is one object of this invention to provide powdered surfactant compositions for use in solid toilet block formulations, where the formulations show enhanced solubility, stability, and foaming and a lack of precipitation. The invention's further object is to provide an enhanced manufacturing process for solid toilet block formulations, incorporating such powdered surfactant compositions.SUMMARY OF THE INVENTION

[0009] The present invention relates to powdered surfactant compositions, hereinafter also in short "surfactant compositions" or "surfactant composition comprising branched alcohol sulfates as anionic surfactants in combination with inorganic salts, in particular for use in solid toilet block formulations.

[0010] It was surprisingly found that simple surfactant compositions comprising branched alcohol sulfates with a specific carbon-chain length display significantly improved cold-water solubility, a very low tendency for precipitation and better hard-water tolerance when compared to state-of-the-art products. High foaming performance was also observed. Furthermore, it was found that by branched alcohol sulfates according to the invention, the processability of the premixes for making solid toilet blocks was significantly improved. Compared to LAS, the presently claimed surfactant compositions also have an enhanced biodegradability, in particular anaerobic biodegradability. The powdered surfactant compositions comprise anaerobically biodegradable alcohol sulfates and display enhanced foaming properties, excellent cold-water solubility and hard water tolerance, resulting in the avoidance of precipitation when used in toilet bowl applications.

[0011] The alcohol sulfates i) comprised in the surfactant compositions according to the invention have the following structure [I]:         R - O - SO 3 X     [I] wherein R = is an alkyl group having 12 or 13 atoms, wherein the average degree of branching in R is from 40 to 96 %; X = is an alkali metal, ammonium or C2- or C3-alkanolammonium ion, preferably sodium.

[0012] In addition, the surfactant composition also comprises one or more inorganic salts ii). The weight ratio of the inorganic salts ii) to alkanol sulfates i) is from 3 : 97 to 20 : 80; and at least 90 wt.%, preferably at least 95 wt.% and more preferably at least 98 wt.% of all anionic surfactants contained in the surfactant composition have structure I.

[0013] Preferably greater than 50 wt.%, more preferably greater than 80 wt.% of the surfactant compositions are alcohol sulfonates of structure [I].

[0014] Preferably, the surfactant composition does not contain alkylbenzene sulfonates and / or alpha-olefin sulfonates.

[0015] The surfactant composition preferably is further free from one or more of alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids; and alpha-olefin sulfonates.

[0016] According to one embodiment, the surfactant composition comprises alcohol sulfates according to structure [I], wherein the branching of R is mainly mono-branched, preferably mainly methyl branched and most preferably mainly methyl-branched on carbon 2 of the alkyl group. "mainly" means more than 60 mol% of all branched alcohol sulfates.

[0017] The alkyl group of the alcohol sulfates of structure [I] preferably have an average degree of branching of 40 to 60 wt%. This means that on average 40 to 60 wt% of all of the alcohol sulfates contained in the surfactant composition have branching. The average degree of branching is the number of all branches in the alcohol sulfates divided by the number of alcohol groups and this provided in percentage. As an example, if there are four molecules of alcohol sulfates and three of the alcohol groups are linear (no branches) and one has two branches, the degree of branching alcohol sulfates of structure [I] is 50 % (2 branches / 4 molecules).

[0018] The inorganic salt of the surfactant composition is selected from the group of sulfates, carbonates, citrates, chlorides and other halogenides, sulphides, oxides, nitrates, acetates, formiates, phosphates, with the counterion selected from the group of Na +< , K +< , NH 4 +< , Ca 2+< , Mg 2+< , Fe 2+< , Al 3+< , C2- to C3- alkanol-ammonium- and C1- to C3-alkylammonium- ions.

[0019] In a specific embodiment of the invention, the inorganic salt of the surfactant composition is or comprises sodium sulfate.

[0020] The surfactant composition may further comprise, besides the inorganic salts, one or more members selected from the group of alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, and / or salts of fatty acids.

[0021] The surfactant composition preferably does not contain alkylbenzene sulfonates und / or and alpha-olefin sulfonates.

[0022] A further embodiment of the invention is the use of the powdered surfactant composition in solid toilet block formulations.

[0023] In a typical embodiment of the use of the surfactant composition the weight ratio of the surfactant composition to the remainder of the solid toilet block formulation is from 10:90 to 40:60.

[0024] According to a further embodiment of the use of the powdered surfactant composition with in a solid toilet block formulation, the toilet block formulation is free from alkylbenzene sulfonates group of inorganic salts,

[0025] The solid toilet block formulation may comprise alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids; and alpha-olefin sulfonates.

[0026] The method for producing the solid toilet block formulations includes a first step of providing a powdered surfactant composition comprising at least one anionic surfactant and an inorganic salt. The surfactant composition is subsequently mixed with one or more components selected from the group of further inorganic salts, alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, salts of fatty acids.

[0027] The weight ratio of the surfactant composition to the remainder of the toilet block formulation is from 10:90 to 60:40, more preferably from 15:85 to 50:50 and most preferably from 20:80 to 40:60. The solid toilet block formulation is optionally free from alkylbenzene sulfonates and alpha-olefin sulfonates.

[0028] The solid toilet block formulation is finally subjected to a molding procedure to obtained a solid shaped article.DETAILED DESCRIPTION

[0029] The powdered surfactant composition of the current invention comprises anionic surfactants based on branched alcohol sulfates, together with inorganic salts, for application in solid toilet block formulations.

[0030] The invention is further described with reference to the figures: Figure 1: Comparison of foaming properties of different anionic surfactants (1 g / l solutions) in hard water (20 °dH, °dH = German degree of hardness of water) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15 s stirring. Figure 2: Comparison of foaming properties of different alcohol sulfates with variations in carbon-chain length and branching degree (1 g / l solutions) in hard water (20 °dH) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15s stirring. Figure 3: Foam profiles of toilet block formulations with different anionic surfactants in 20 °dH water at 10°C. Materials Used:

[0031] The following anionic surfactant were used to demonstrate the efficiency of powdered surfactant composition according to the invention, in comparison to state-of-the-art surfactants as used in conventional powdered surfactant compositions: The anionic surfactant used all were alcohol sulfates based on the general formula:         R-O-SO 3 -X

[0032] With R = alkyl carbon chain and X = Na +< . Table 2: Surfactant used to demonstrate efficiency comprising sodium sulfate as the inorganic saltSurfactants used TRADE NAME ANIONIC SURFACTANT NATURE OF R-GROUP SAFOL 23 Sulfate (PBAS1) Partially branched alcohol sulfateC 12-13 carbon chain; 50 wt% branching (methyl and other branching on any C-atom)R - O - SO 3 -NaLIAL123 Sulfate (PBAS2) Partially branched alcohol sulfateC 12-13 carbon chain; 40 - 60 wt% branching (mono-methyl branched, mostly on C2 atom)R - O - SO 3 -NaISALCHEM 123 Sulfate (FBAS3) Fully branched alcohol sulfateC 12-13 carbon chain; 90 - 95 wt% branching (mono-methyl branched, mostly on C2 atom)R - O - SO 3 -NaComparative Compositions C 12-14 fatty alcohol sulfate (C 1214 FAS) sodium saltLinear fatty alcohol sulfateC 12-14 carbon chain; linear, derived from palm kern oilR - O - SO 3 -NaMARLINAT 242 / 70 RSPO-MB (SLES) sodium laureth ether sulfateLinear alkyl ether sulfate R - O - EO 1-3 -SO 3 Na with EO = ethylene oxideC 12-14 carbon chain; linear(LAS-Na) MARLON ATFLinear alkylbenzene sulfonic acid, sodium saltC 10-13 carbon chain; linearNACOL 10 FAS (C 10 FAS) Linear fatty alcohol sulfateC 10 carbon chain; linear, < 5 wt% branchedR - O - SO 3 -NaLIAL145 Sulfate (C 1415 PBAS) Partially branched alcohol sulfateC 14-15 carbon chain; 40 - 60 wt% branching (mono-methyl branched, mostly on the C2 atom)R - O - SO 3 -Na EXPERIMENTAL SECTIONPreparation of the alcohol sulfates:

[0033] Alcohol sulfates can be produced in different ways that are commonly known to a person skilled in the art. A well-known procedure is the sulfation of alcohols with sulfur trioxide in a falling film tube reactor (Kosswig, Kurt (2000). "Surfactants". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH). It is also possible to sulfate alcohols in a batch process with oleum or chlorosulfuric acid (Eduard Smulders et al. "Laundry Detergents" in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim; Klaus Noweck et al, "Fatty Alcohols" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim). All alcohol sulfates were produced using a falling film reactor. The alcohols were treated with sulfur trioxide / air mixture with subsequent neutralization with NaOH-solution. The addition of the NaOH-solution resulted in up to 0.5 wt.% additional salts.

[0034] The following experiments were carried out to demonstrate the advantages of surfactants as used in the powdered surfactant composition of the invention.Water solubility / stability in demineralised water

[0035] The appearance of the compositions dissolved in demineralised water at room temperature comprising the branched alcohol sulfates PBAS1 only was visually compared to the linear C 12-14 fatty alcohol sulfate C 1214 FAS,) at different concentrations of 1 g / l, 5 g / l, 10 g / l (all surfactant actives) in demineralised water, after storage for 72 h at 7 °C. Table 3: Appearance of a partially branched alcohol sulfate PBAS1 and linear C12-14 fatty alcohol sulfate (C1214 FAS) at different concentrations in demineralised water after 72 h at 7 °C .Surfactant type1 g / l5 g / l10 g / lPBAS 1ClearClearClearC12-14 FASSlightly turbid / sedimentationTurbid / sedimentationTurbid / sedimentation

[0036] PBAS1 provided a water-clear solutions at concentrations from 1 to 10 g / l, after 72 h stored at 7°C. Linear C 12-14 fatty alcohol sulfate (C 12-14 FAS), however, crystallized in typical shapes, such as needles or plates already at concentrations of 1 g / l, with an increasing amount of crystals at 5 g / l and 10 g / l causing a turbid / milky phase for more of 50% at 5 g / l and more of 75% (at 10 g / l) of the filling hight.

[0037] Partially branched alcohol sulfates different in branching were used for the comparison. The cold-water solubility test was done with PBAS2 at lower temperatures (4°C). Table 4: Appearances of PBAS1 and branched alcohol type 2 (PBAS2) at different concentrations in demineralised water, after 72 h at 4 C.Surfactant type1 g / l5 g / l10 g / lPBAS 1ClearClearSlightly precipitatedPBAS 2ClearClearSlightly precipitated

[0038] In Table 4, PBAS1 and PBAS2 were mixed at three different concentrations (1, 5 and 10 g / l alkanol sulfates according to structure [1] (without the inorganic salts) in demineralised water, stored for 2 days at 4°C). Excellent cold-water solubilities are demonstrated under these conditions, with only slight precipitation observed at the bottom of the glass containers and no turbid / milky phase.

[0039] The effect of longer carbon-chain length for R and of variations in the branching on solubility at low temperatures was demonstrated in the following experiment. Table 5: Appearances of FBAS3 (1), C 1415 PBAS (2) and C 10 FAS (3) at different concentrations in demineralised water, after 72 h at 4 C. (a: 1 g / l, b: 5 g / l and c: 10 g / l)Surfactant type1 g / l5 g / l10 g / lFBAS 3ClearClearClearC1415 PBASSlightly precipitatedTurbid / precipitatedTurbid / precipitatedC10 FASClearClearPrecipitated

[0040] Table 5 shows that a fully branched C 12-13 AS (FBAS3) demonstrated good solubility at 4°C, while a branched C 14-15 AS (C 1415 PBAS) precipitated and resulted in sedimentation. A linear C 10 AS (C 10 FAS) showed good solubility but precipitated at 10 g / l.

[0041] Although toilet temperatures of 4°C are unlikely for common households in Europe, the test results above demonstrate the advantage the claimed alcohol sulfates have at low temperatures. However, the suitability of the alcohol sulfates is not only a matter of their cold-water solubility but also depends on other factors such as foam formation and hard-water tolerance.Foaming behaviour

[0042] Foaming is an important property of toilet block formulations. In household applications tap water is used that generally ranges from soft to hard water. The surfactants used should, therefore, cause fast foam formation and high foaming across a wide range of conditions.

[0043] A SITA Foam Tester R-2000 was used to evaluate the foaming behaviour. All surfactants were dissolved at concentrations of 1 g / l (active matter) in water with 20 °dH [equivalent to 356 ppm CaCO 3 ]. Tests were carried out at 20°C. Foam volume values were measured after 15 s of stirring at 1100 rpm. For comparison, a commercially available C 12-14 -based ether sulfate (sodium laureth ether sulfate (SLES), MARLINAT 242 / 70 RSPO-MB) was used, which does not show precipitation in hard water.

[0044] Figure 1 shows the different foaming properties of the tested surfactants in hard water. The commercially available product, SLES, demonstrated a typical fast and high foaming behaviour using the described test method. LAS (sodium salts) are known to be sensitive to water hardness and show moderate foaming.

[0045] C 12-14 fatty alcohol sulfates (C 1214 FAS) displayed significantly lower foaming, which was not caused by solubility problems at low temperatures but rather resulted from the formation of insoluble Ca- / Mg- adducts. Surprisingly, the partly branched C 12-13 AS (PBAS1) showed similar high foaming behaviour compared to SLES. The velocity of foam formation was not as rapid as for SLES, but the anionic surfactant demonstrated a surprisingly good foam profile under these conditions.

[0046] To determine if variations in carbon-chain length or in the branching degree will have a positive or negative influence on the foaming behaviour in hard water (20°dH) at 20°C, the following sodium salts of the alcohol sulfates, were tested (see Table 6): Table 6: Variation in surfactant carbon-chain lengthC-chain cut Branching Abbreviation C 12-13 50 %PBAS1C 12-13 90-95 %FBAS3C 10 <5 %C 10 FASC 14-15 40-60 %C 1415 PBAS

[0047] The foam profile was again determined using the same method and parameters described before (see Figure 2).

[0048] Figure 2 shows the foam formation for the different alcohol sulfates of Table 6. In hard water (20 °dH), FBAS3 showed a slightly faster foam formation compared to PBAS1. The longer carbon-chain length alcohol sulfate C 14-15 PBAS showed foam foam . Shorter carbon-chain length surfactants, in this case C 10 FAS, showed some foam formation (but not as high as the C 12-13 types).Process to manufacture powdered alcohol sulfates / toilet block formulations

[0049] For the drying process of the liquid, branched alcohol sulfate slurry to the corresponding powder, a drum dryer is preferred. Spray-drying and other commonly known technologies are, however, feasible as well. The choice of drying techniques will determine further properties like morphology, bulk density and furthermore dissolving properties or capability for further processing. The specific drying technique chosen is therefore one factor to determine its suitability for the subsequent application and formulation type. The use of different inorganic salts, oxides or organic additives can adjust different properties like stickiness, flowability etc. as demanded, and can be suitably adjusted by the person skilled in the art.

[0050] In general, sodium salts of partially branched alcohol sulfates with active matters between 30 and 45 wt% or between 60 and 75 wt% can be mixed with inorganic salts to determine the properties of the resulting powder. According to one embodiment sodium citrate, sodium sulfate and / or sodium carbonate can be used alone or in combination. Sodium salts are generally preferred.

[0051] In the following examples, the premixes (slurries) were made by using PBAS1 with 40% active matter. The composition of such a premix is given in Table 7. Table 7: Slurry as premix for drum-drying to powderRaw material Slurry mix (g) Slurry mix (actives) (wt%) PBAS1 (40 wt% surfactant)10038sodium sulfate contributed by PBAS10.5Sodium sulfate33.5Sodium citrate22Sodium carbonate11Water (additional)-55.5Sum106100

[0052] The homogeneously stirred slurry is deposited between the two drums of a drum dryer. The heated rotating drums dry the slurry to a brittle mass which is thereafter removed by knives and transported to a mill to break the aggregates.

[0053] Typical concentration ranges of the components of the powder for making the solid toilet block formulation are shown in Table 8 after vaporizing the water to a water content of max. 2 wt% remaining. Table 8: Powdered branched alcohol sulfate compositionRaw material Actives (wt%) PBAS175-93Sodium sulfate2-8Sodium citrate2-8Sodium carbonate0-6Water0-2

[0054] Typically, the sum of the inorganic salts is between 3 and 15 wt% of the powdered surfactant composition. The resulting powder has a white to slightly yellowish appearance, and a bulk densities of 350 to 550 g / l.

[0055] In order to test the use of differently branched alcohol sulfates in toilet block formulations, the following formulations were used where the liquid components have to be adjusted to soft mixtures easily moldable. The consistency of the mixture is important for the shaping process in order to achieve the desired shape (see Table 9). Table 9: Test formulations for toilet blocksRaw material Test formulation (g) Sodium sulfate60PBAS 128C 1618 -ethoxylated (25 EO) alcohol)5Monopropylene glycol2Demineralised water2

[0056] All formulations were mixed to achieve a homogeneous soft dough-like substance within 30 min, using a lab kneader. In the test formulation, the liquid components were varied, starting with 2 ml total liquids, to get a soft mixture / "dough", which was manually formed into the shape of balls. The shaped balls were formed directly after the mixing process and were visually tested to observe whether closed balls without cracks were formed. This property is of importance for processing of the toilet blocks in an industrial manufacturing process: Table 10: Experiments to achieve sufficient softness for shaping / processing.Raw material A (comparative) B (comparative) C (inventive) wt% Sodium sulfate62.96061.9LAS-NA powder, 88% actives29.300C 1214 FAS0280PBAS10028.9C 16-18 -25 EO EMULDAC AS25 (linear ethoxylated alcohol)5.255.2Monopropylene glycol1.33.52Demineralised water1.33.52TOTALS:100100100

[0057] Formulation A from Table 10 contained LAS-Na powder, required the lowest amounts of liquid components (monopropylene glycol + water = 2.6 wt%) to be added, in order to achieve sufficient processability. This was followed by the branched alcohol sulfate (Formulation C = 4 wt% liquid components). For Formulation B (containing C 1214 FAS) the mass was very hard to form, and the addition of liquid components up to 7 wt% was required.

[0058] Compositions A and C with branched alcohol sulfate showed clear advantages when compared to composition B, which comprised linear fatty alcohol sulfates with regard to the processability of the mixtures. This property is important to avoid problems with automatic shaping devices in the production of shaped solid toilet block formulations.

[0059] To test the foaming behaviour of the toilet block formulations comprising PBAS 1 under conditions present in a toilet, it was assumed that the water temperature is 10°C, using synthetic hard water with 20°dH. The tests were carried in a SITA-Foam Tester R-2000 under the same conditions as for Figures 1 and 2 (except for the temperature being 10°C).

[0060] Figure 3 shows the effect of hard water and low temperature on the foamability of different toilet block formulations. Formulation B (C 1214 FAS-based) did not display favourable foaming behaviour. Due to its low hard-water tolerance, the resulting solution was turbid and foaming was depressed.

[0061] Formulation A based on LAS-Na showed better performance, but foaming was still limited to a maximum value of 150 ml. Formulation C, based on PBAS1, displayed superior foaming behaviour.Stability tests

[0062] Apart from the challenge of obtaining good foaming when used in hard- or cold-water conditions, precipitation of the anionic surfactants in the toilet bowl must be kept at a minimum. Tests were carried out storing different 1 wt% actives solutions (base formulations) (see Table 11) in tap water (12 °dH) for 72 h at 10°C and 23°C. The results are shown in Table 11 below. Table 11: Appearance of solutions of different surfactants in tap water (12 °dH) at 23 °C and 10 °C, stored for 72 h.Surfactant typeAppearance at 23°CAppearance at 10 °CLASClearClearC12-14 FASClearPrecipitation / turbidPBAS 1ClearClear

[0063] No precipitation occurred and at 23°C water-clear solutions were obtained for all base formulations.

[0064] At 10°C, the base formulation with C 1214 FAS showed precipitation and sedimentation of the anionic surfactant. The formulation based on LAS and PBAS1 did not show significant precipitation under these conditions at 10°C.

Examples

Embodiment Construction

[0029]The powdered surfactant composition of the current invention comprises anionic surfactants based on branched alcohol sulfates, together with inorganic salts, for application in solid toilet block formulations.

[0030]The invention is further described with reference to the figures:

Figure 1: Comparison of foaming properties of different anionic surfactants (1 g / l solutions) in hard water (20 °dH, °dH = German degree of hardness of water) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15 s stirring. Figure 2: Comparison of foaming properties of different alcohol sulfates with variations in carbon-chain length and branching degree (1 g / l solutions) in hard water (20 °dH) at 20°C. Measured with SITA Foam Tester R-2000, 1100 rpm, 10x15s stirring. Figure 3: Foam profiles of toilet block formulations with different anionic surfactants in 20 °dH water at 10°C.

Materials Used:

[0031]The following anionic surfactant were used to demonstrate the efficiency of powdered surfac...

Claims

1. A powdered surfactant composition comprising i) alkanol sulfates having the following structure:         R-O-SO3X     [I] wherein R = alkyl group having 12 or 13 carbon atoms, wherein the degree of branching is 40 to 96 wt%; X = an alkali metal, ammonium or C2- or C3-alkanolammonium ion; and ii) one or more inorganic salts; wherein the weight ratio of the inorganic salts to the alkanol sulfates is from 3:97 to 20:80; and at least 90 wt.% of all anionic surfactants contained in the powdered surfactant composition have structure [I].

2. The composition of claim 1, wherein the weight ratio of inorganic salt to anionic surfactant is from 3:97 to 15:85, preferably from 6:94 to 12:88.

3. The composition of claim 1 or 2, wherein the branching is a mono-branching, preferably where the mono-branching is a methyl branching and most preferably methyl-branching on carbon 2 of the alkyl group only.

4. The composition according to any of the preceding claims, wherein the average degree of branching is from 40 to 60 wt%.

5. The composition according to any of the preceding claims, wherein X is a sodium ion.

6. The composition according to any of the preceding claims, wherein the inorganic salt is selected from one or more members of the group of: sulfates, carbonates, citrates, chlorides and other halogenides, sulphides, oxides, nitrates, acetates, formiates, phosphates, with the counterion selected from the group of Na+, K+, NH4+, Ca2+, Mg2+, Fe2+, Al3+, alkanolammonium- and alkylammonium-ions, preferably citrate and / or sulfates.

7. The composition according to any of the preceding claims , wherein the inorganic salt is an alkaline metal salt, preferably sodium sulfate.

8. The composition according to any of the preceding claims , wherein greater than 50 wt.%, more preferably greater than 80 wt.% of the surfactant compositions are alcohol sulfonates of structure [I].

9. The composition according to any of the preceding claims, wherein the surfactant composition does not contain alkylbenzene sulfonates and / or alpha-olefin sulfonates.

10. Use of the powdered surfactant composition according to any of the preceding claims, in solid toilet block formulations for cleaning a toilet bowl.

11. The use of claim 10, wherein the weight ratio of the surfactant composition to the remainder of the solid toilet block formulation is from 10:90 to 40:60.

12. The use of claims 10 or 11, wherein the toilet block formulation further comprises one or more components selected from the group of additional inorganic salts, alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, and salts of fatty acids, and wherein the toilet block formulation is free from alkylbenzene sulfonates and alpha-olefin sulfonates.

13. A method of producing a solid toilet block formulation, the method comprising at least the following steps: a) providing a powdered surfactant composition according to any of claims 1 to 09; b) mixing the powdered surfactant composition with one or more additional components selected from the group of inorganic salts, alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes and / or salts of fatty acid, and wherein the weight ratio of the powdered surfactant composition to remainder of the toilet block formulation is from 10:90 to 60:40, preferably from 15:85 to 50:50, most preferably from 20:80 to 40:60; and c) subjecting the product of step b) to a molding procedure, wherein the solid toilet block formulation preferably is free from alkylbenzene sulfonates and / or alpha-olefin sulfonates; and wherein preferably 50 - 80 wt.% of the solid toilet block formulation are the additional components b).

14. A solid toilet block formulation comprising from 10:90 to 40:60 of the powdered surfactant composition according to any of the preceding claims 1 to 09, further comprising one or more components selected from the group of inorganic salts, alkoxylated alcohols, alkyl glycols, water, solvents, builders, auxiliary agents, fragrances, dyes, polyethylene glycols, waxes, and / or salts of fatty acids; and wherein the weight ratio of the powdered surfactant composition to remainder of the toilet block formulation is from 10:90 to 60:40, preferably from 15:85 to 50:50, most preferably from 20:80 to 40:60; wherein the solid toilet block formulation is preferably free from alkylbenzene sulfonates and / or alpha-olefin sulfonates.

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