Process for making concentrated surfactant blends

Abstract

The need for concentrated surfactant blends containing alkyl sulfated anionic surfactants that do not require high pH to be hydrolytically stable and therefore do not contain high concentrations of salts or require the addition of high concentrations of organic solvents or structurants to be stable, and can be used to form detergent compositions with desired viscosity, dissolution, and foaming profiles is met by a process in which a buffer surfactant is added prior to or during the neutralization step of the alkyl sulfate stream to form the alkyl sulfated anionic surfactant.

Description

[Technical field]

[0001] The present invention relates to a process for making concentrated surfactant blends, particularly concentrated surfactant blends for use in making liquid detergent compositions, especially liquid hand dishwashing cleaning compositions. [Background technology]

[0002] Liquid hand dishwashing detergent compositions typically provide high foaming and long-lasting foam in addition to good grease removal to provide a high level of consumer satisfaction.Generally, such detergent compositions contain alkyl sulfated anionic surfactants to provide both long-lasting foam and good grease removal during use.Alkyl sulfated anionic surfactants include non-alkoxylated alkyl sulfate surfactants and alkoxylated alkyl sulfate surfactants, such as ethoxylated alkyl sulfate surfactants.

[0003] Liquid hand dishwashing detergent compositions typically include co-surfactants as part of the surfactant system to further enhance cleaning and foaming performance. Such co-surfactants can include amphoteric surfactants, such as amine oxide surfactants, zwitterionic surfactants, such as betaine surfactants, and mixtures thereof.

[0004] To convey to the user the "richness" of the formulation, liquid dishwashing detergent compositions should also have a high viscosity.

[0005] Such alkyl sulfated anionic surfactants (including alkoxylated and non-alkoxylated alkyl sulfate surfactants) are made by a process involving a sulfation step, followed by a neutralization step.

[0006] While various reagents have been used for the sulfation step, sulfur trioxide (SO3) is particularly preferred, at least in part, due to its low cost. Such processes are typically carried out using membrane reactors, such as annular falling film reactors, or multitubular membrane reactors, such as the "Ballestra" reactor. In such processes, the SO3 is typically first diluted with ambient air. Such ambient / SO3 sulfation processes are direct processes in which the SO3 gas is diluted with very dry ambient air and reacted directly with the alkyl alcohol feedstock. The reaction of gaseous SO3 with the alkyl alcohol is rapid and stoichiometric. Such processes are complicated by the possibility of side reactions, however, with strict process control very high purity alkyl sulfate surfactants can be achieved. However, the reaction typically does not go to completion. Thus, some acid residue remains, which needs to be neutralized to achieve the desired pH of the blend. The resulting blend therefore contains neutralized salt and unreacted alkyl alcohol. Both result in reduced phase stability, especially at low temperatures.

[0007] Alternatively, sulfamic acid can be used in the sulfation step to form the ammonium salt. Sulfamic acid is a mild and specific sulfation reagent suitable for making ammonium neutralized alcohol ethoxylates. The advantage of sulfamic acid is that it selectively sulfates the alcohol group and does not sulfonate the aromatic ring. It is therefore particularly suitable for sulfation of alkylphenol ethoxylates to prevent the formation of mixed sulfate-sulfonate compounds. The advantage of using sulfamic acid as a reagent is that a neutralized form of the sulfate surfactant is produced. However, sulfamic acid is an expensive reagent. Furthermore, when using sulfamic acid, only ammonium neutralized salts of alkyl sulfate surfactants can be made. The pH of compositions containing such ammonium salts of alkyl sulfate surfactants needs to be less than 8 to avoid an ammonia odor from the detergent composition, limiting the applications of surfactants made using this sulfation reagent. Alternatively, ion exchange processes can be used to replace the ammonium ions with sodium or other ions. However, such ion exchange processes are expensive and typically not cost-effective for applications such as household detergent compositions. Furthermore, such processes result in low surfactant concentrations in the resulting blends, typically less than 30%, limiting their use in low activity detergent compositions and increasing the costs of transporting the blends.

[0008] Chlorosulfuric acid (ClSO3H) can also be used to produce alkyl and alkyl ether sulfates. Chlorosulfuric acid is substantially less expensive than sulfamic acid, but is still substantially more expensive than other reagents. In addition, the use of such reagents adds additional equipment and complexity to the process, especially as the reaction moves toward completion, due to the release of hydrochloric acid (HCl). This acid must be washed or otherwise recovered.

[0009] In most commercial processes used to make alkyl sulfate surfactants, such as the air / SO3 process and the process using chlorosulfonic acid, the acid form of the alkyl sulfate surfactant is formed. However, this acid form of the alkyl sulfate surfactant is not stable and must be neutralized immediately after the sulfation step, since hydrolysis back to the alkyl alcohol and the starting acid is rapid at a pH below 7. Sodium hydroxide is the most common neutralizing agent used in the neutralization step. However, other neutralizing agents can be used, such as potassium hydroxide, ammonia, monoethanolamine, diethanolamine, and triethanolamine, among others. To reduce the hydrolysis of the neutralized alkyl sulfate back to the alkyl alcohol and sulfuric acid, an excess of neutralizing agent is typically added during the neutralization step. However, some hydrolysis still occurs, which leads to a downward trend in pH, since such prior art alkyl sulfate blends are only weakly buffered or not buffered at all. The resulting increase in sulfuric acid present autocatalyzes the hydrolysis reaction, resulting in an even more rapid drop in pH as more acid is formed. As a result, alkyl sulfate blends neutralized using sodium hydroxide or other alkali metal hydroxides are typically neutralized to a high pH, ​​between 11.0 and 13.0.

[0010] Typically, alkyl sulfate-containing surfactant blends are used to make detergent compositions with a pH of 7.0-9.0. Thus, the pH of the detergent composition needs to be "adjusted" using an acid such as citric acid or HCl. As a result, high concentrations of salt are typically present in the composition, which creates both viscosity and phase stability challenges, especially at low temperatures. Thus, more organic solvents or structuring agents need to be added to provide the desired low temperature stability and viscosity profile. This also makes the formulation of the final liquid detergent composition more complex, as high salt and high solvent concentrations can affect the solubility of other actives. High salt concentrations also make the detergent composition less soluble, resulting in greater dissatisfaction from users.

[0011] Prior to sulfation, the alkyl alcohol can be alkoxylated, particularly ethoxylated. The resulting alkyl alkoxylated sulfate surfactant provides improved low temperature stability to the resulting liquid detergent composition while also providing the desired level of grease and oil cleaning and foaming performance. When making alkoxylated, particularly ethoxylated, alkyl sulfate surfactants, 1,4-dioxane can be produced. Typically, both the alkoxylation, particularly ethoxylation, and sulfation steps require strict control of process conditions and feedstock composition to minimize the amount of 1,4-dioxane by-product in the alkoxylated, particularly ethoxylated alkyl sulfate. Even if the 1,4-dioxane by-product concentration is kept to a minimum in the freshly formed surfactant blend, the concentration of 1,4-dioxane by-product increases over time for many blends formed from prior art processes. It has been found that the formation of 1,4-dioxane is higher when the concentrated alkyl ethoxylated sulfate blend is stored at a higher pH.

[0012] Therefore, there is still a need for a process for forming concentrated surfactant blends containing alkyl sulfated anionic surfactants that do not require high pH to be hydrolytically stable, and therefore can be used to form detergent compositions that are stable and have desired viscosity profiles and do not require high salt concentrations or the addition of high organic solvents or structurants.Furthermore, there is a need for a process that makes concentrated surfactant blends that are more stable, especially at low temperatures.In addition, there is still a need for a process for forming concentrated surfactant blends containing alkyl alkoxylated sulfates that have low concentrations of 1,4-dioxane by-products and do not substantially increase 1,4-dioxane by-products over time.

[0013] US Patent Nos. 4,477,372(A), 4,476,044(A) and 4,476,045(A) relate to high actives content surfactants in which the anionic portion of the surfactant contains at least three carbon atoms bonded to the nitrogen atom of the amine, at least one alcoholic hydroxyl group therein, neutralized with a secondary or tertiary amine such that the amine is alpha or beta substituted to the nitrogen atom product. WO 9,418,160(A) relates to a process for producing a high activity alkyl sulfate solution comprising the steps of adding and mixing an alkyl sulfate having a chain length of C12-C18 with an organic amine to produce a neutralized product substantially free of water. EP 2,964,741(A) relates to a method for preparing a substantially anhydrous composition of alkyl (ethoxy) sulfate neutralized with an organic amine base, which composition is suitable for use as a surfactant in ecodoses. WO201472840(A) relates to a process for preparing a highly concentrated, flowable aqueous fatty alkyl sulfate solution, the process comprising: (i) ethoxylating a fatty alcohol with very low ethylene oxide of about 0.3 to about 0.8 moles; (ii) sulfating the ethoxylated fatty alcohol under specific reaction conditions; and (iii) neutralizing the sulfation product with an aqueous base, the resulting fatty alkyl sulfate solution comprising at least 65% by weight of a mixture of fatty alkyl sulfate and fatty alkyl ether sulfate in a weight ratio ranging from about 80:20 to about 50:50, the average moles of ethylene oxide (EO) of the mixture being 0.3 to 0.8, less than 3 ppm dioxane, and water, the solution being homogenous, flowable, and pumpable at 25°C without any antimicrobial or preservatives. WO 9738972(A) relates to a sulfation process for producing longer chain length alkyl sulfate and / or alkyl alkoxylated sulfate surfactant compositions, which process utilises the presence of significant amounts of mid-chain branched alcohols and / or polyoxyalkylene alcohols in the sulfation reaction to significantly reduce the reaction temperature, thereby improving product quality and saving energy.WO 9404640(A) relates to concentrated aqueous surfactant solutions comprising alkyl ether sulfates and an alkaline earth metal, preferably magnesium, the compositions being stable liquids suitable for making into cleaning products, especially dishwashing liquids, and the concentrated surfactant solutions can be prepared by partial neutralization of an acid precursor with an alkaline earth metal hydroxide or oxide, followed by further neutralization with an alkali metal or ammonium hydroxide. WO 9105764(A) relates to the sulfation of ethoxylated alkanols obtained by reaction of ethylene oxide with alcohols containing 8 to 22 C atoms in the presence of a hydrotalcite catalyst, giving alkyl polyethoxyether sulfates characterized by a low dioxane content and very good coagulation properties using normal electrolytes. US Patent Publication No. 20170158625(A) relates to a process for preparing alcohol ether sulfates comprising (a) sulfating an alkoxylated alcohol and (b) neutralizing the sulfated product of step (a) in the presence of a base and a co-solvent having a flash point of at least 60° C. GB Patent No. 977281(A) relates to surface active sulfates of alkyl ether alcohols, where the ether alcohols may be made by (a) reacting an olefin with ethylene glycol, (b) reacting an olefin with an ethylene halohydrin followed by hydrolysis of the halogen-containing product, or (c) reacting a secondary or tertiary alcohol with ethylene oxide, all of which are sulfated with chlorosulfonic acid. EP 3919594(A1) relates to a liquid detergent composition suitable for washing dishes, which is compatible with both in-sink and direct application methods, having good foam persistence, particularly under in-sink application methods, and good viscosity, while providing reduced smearing when used in direct application dishwashing methods, the liquid detergent composition comprising an alkyl sulfate anionic surfactant comprising a C13 alkyl sulfate anionic surfactant, the C13 alkyl sulfate anionic surfactant comprising a specific fraction of 2-branched C13 alkyl sulfate anionic surfactant with a specific distribution of 2-branched. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] U.S. Patent No. 4,477,372(A) [Patent Document 2] U.S. Patent No. 4,476,044(A) [Patent Document 3] U.S. Patent No. 4,476,045(A) [Patent Document 4] International Publication No. 9418160(A) [Patent Document 5] European Patent No. 2964741(A) [Patent Document 6] International Publication No. 201472840(A) [Patent Document 7] International Publication No. 9738972(A) [Patent Document 8] International Publication No. 9404640(A) [Patent Document 9] International Publication No. 9105764(A) [Patent Document 10] U.S. Patent Application Publication No. 20170158625(A) [Patent Document 11] British Patent No. 977281(A) [Patent Document 12] European Patent No. 3919594(A1) Summary of the Invention [Means for solving the problem]

[0015] The present invention relates to a process for making a concentrated surfactant blend, the concentrated surfactant blend comprising an alkyl sulfated anionic surfactant and a buffer surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, the process comprising the steps of providing an alkyl alcohol stream comprising at least one alkyl alcohol, a sulfation step, where at least one alkyl alcohol in the alkyl alcohol stream is sulfated to form an alkyl sulfate stream comprising at least one alkyl sulfate, providing a neutralization stream comprising at least one neutralizing agent, a neutralization step, where the alkyl sulfate stream and the neutralization stream are combined to neutralize the alkyl sulfate, the buffer surfactant being added before or during the neutralization step, the buffer surfactant being added at a concentration that provides the resulting concentrated surfactant blend with a reserve alkalinity of greater than 0.02 when measured as a 10 wt % solution of the concentrated surfactant blend in demineralized water at 20° C., and the resulting concentrated surfactant blend has a pH of 7.1 to 10 when measured as a 10 wt % solution of the concentrated surfactant blend in demineralized water at 20° C.

[0016] The present invention further relates to a concentrated surfactant blend comprising 30% to 70% by weight of the concentrated surfactant blend of an alkyl sulfated anionic surfactant, the alkyl sulfated anionic surfactant having an average degree of alkoxylation of less than 0.5, and 1.0% to 25% by weight of the concentrated surfactant blend of a buffer surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, the concentrated surfactant blend having a reserve alkalinity of greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C. using the method described herein, and the resulting concentrated surfactant blend having a pH of 7.1 to 10 when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] It has been found that adding a buffer surfactant before or during the neutralization step results in a concentrated surfactant blend that is more stable to hydrolysis and therefore can be maintained at a lower pH. Furthermore, when such concentrated surfactant blends are formulated into detergent compositions, less acid needs to be added to reach the desired pH. The resulting liquid detergent composition therefore contains less salt and is therefore more phase stable, especially at low temperatures, without the need for additional organic solvents. In addition, the desired viscosity can be achieved with little or no organic solvents and / or added structurants. It has also been found that the lower salt content in the final product composition promotes the dissolution of the final product and accordingly results in a faster onset of foam formation during washing. Furthermore, the concentrated surfactant blend can be maintained at a lower pH, reducing or eliminating the formation of 1,4-dioxane both during preparation and storage.

[0018] Although salt-based buffer systems can limit the pH trend of concentrated surfactant blends, they introduce additional salt into the final detergent composition, which adversely affects both low temperature stability and viscosity. In contrast, the buffered surfactants used herein provide cleaning and foaming benefits in addition to buffering, without adversely affecting the viscosity and physical product stability of the composition.

[0019] As used herein, articles such as "a" and "an" used in the claims are understood to mean one or more of what is claimed or described.

[0020] As used herein, the term "comprising" means that steps and ingredients other than those specifically mentioned can be added. This term encompasses the terms "consisting of" and "consisting essentially of." The compositions of the present invention can include, consist of, or consist essentially of the essential elements and limitations of the invention described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein.

[0021] As used herein, the term "dishware" includes, by way of non-limiting examples, cookware and tableware made from ceramic, china, metal, glass, plastic (e.g., polyethylene, polypropylene, polystyrene, etc.), and wood.

[0022] As used herein, the term "fat" or "oleaginous" means that the material comprises, at least in part (i.e., at least 0.5% fat by weight of the material), saturated and unsaturated fats and oils, preferably oils and fats derived from animal sources such as beef, pork, and / or chicken.

[0023] The terms "include / includes / including" are meant to be non-limiting.

[0024] As used herein, the term "particulate soil" refers to inorganic and especially organic solid soil particles, especially food particles, non-limiting examples of which include ultrafine particulate elemental carbon, baked grease particles, and meat particles.

[0025] As used herein, the term "suds profile" refers to the characteristics of a cleaning composition with respect to the foam properties during the dishwashing process. The term "suds profile" of a cleaning composition includes the initial foam volume generated upon dissolving and stirring the cleaning composition in an aqueous cleaning solution, typically by hand stirring, and the retention of foam during the dishwashing process. Preferably, a hand dishwashing cleaning composition characterized as having a "good suds profile" tends to have a high initial foam volume and / or a persistent foam volume, especially over a significant portion or the entire hand dishwashing process. This is important because consumers use high sudsing as an indicator that enough cleaning composition has been dispensed. Furthermore, consumers also use the persistent foam volume, even toward the end of the dishwashing process, as an indicator that enough active cleaning ingredients (e.g., surfactants) are present. Consumers typically refresh the cleaning solution when sudsing becomes low. Thus, low sudsing cleaning compositions tend to be replenished by consumers more frequently than necessary due to the low sudsing levels.

[0026] It will be understood that the test methods disclosed in the Test Methods section of this application must be used to determine the values ​​of each of the parameters of Applicants' inventions described and claimed herein.

[0027] Unless specifically stated otherwise, as is clear from the context, all percentages are by weight of the total composition, all ratios are by weight unless specifically stated otherwise, and all measurements are made at 25° C. unless otherwise specified.

[0028] Process for making concentrated surfactant blends The process is used to make a concentrated surfactant blend comprising an alkyl sulfated anionic surfactant and a buffering surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof.

[0029] The process is a) providing an alkyl alcohol stream comprising at least one alkyl alcohol; b) a sulfation step in which at least one alkyl alcohol in the alkyl alcohol stream is sulfated to form an alkyl sulfate stream comprising at least one alkyl sulfate; c) providing a neutralization stream comprising at least one neutralizing agent; d) combining the alkyl sulfate stream with the neutralization stream to neutralize the alkyl sulfate; A buffering detergent is added before or during the neutralization step.

[0030] The buffer surfactant is added at a concentration that provides a resulting concentrated surfactant blend with a reserve alkalinity of greater than 0.02, when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C., using the methods described herein, and the resulting concentrated surfactant blend has a pH of 7.1 to 10, when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C.

[0031] Buffer capacity is the ability to neutralize pH and resist changes in pH due to small amounts of acidity or base in or out. If a system is not well buffered, the addition of even a small amount of acid or base will change its pH significantly, whereas if a system is well buffered, the same addition will not change its pH very much.

[0032] Reserve alkalinity is a measure often used in industry to indicate the amount of alkaline components present in a product. In some compositions, such as the concentrated surfactant blends disclosed herein, it is more important to know the reserve alkalinity of the blend rather than the buffer capacity, since the reserve alkalinity provides a measure of the ability of the blend to neutralize any acid present or formed in situ, thus maintaining an alkaline pH.

[0033] Alkyl alcohol stream The process described herein includes a step in which an alkyl alcohol stream is provided. The alkyl alcohol stream comprises at least one alkyl alcohol. The alkyl alcohol stream itself can comprise one alkyl alcohol, or alternatively a blend of alkyl alcohols.

[0034] The molar average alkyl chain length of the alkyl alcohol or blend of alkyl alcohols may be from 8 to 18, preferably from 10 to 14, more preferably from 12 to 14, and most preferably from 12 to 13 carbon atoms to provide a combination of improved foaming and grease removal with improved cleaning speed from the resulting alkyl sulfate surfactant.

[0035] The alkyl chains of the alkyl alcohol or blend of alkyl alcohols may have a molar fraction of C12 and C13 chains of at least 50%, preferably at least 65%, more preferably at least 80%, most preferably at least 90%. When the C13 / C12 molar ratio of the alkyl chains in the alkyl alcohol or blend of alkyl alcohols used to prepare the alkyl sulfate surfactant is at least 57 / 43, preferably between 60 / 40 and 90 / 10, even more preferably between 60 / 40 and 80 / 20, most preferably between 60 / 40 and 70 / 30, foam persistence is particularly improved, especially in the presence of greasy soils, while at the same time foam persistence in the presence of particulate soils is not impaired.

[0036] The relative molar amount of C13 and C12 alkyl chains in an alkyl alcohol or blend of alkyl alcohols can be obtained from the carbon chain length distribution in the alkyl chain of the alkyl alcohol. The carbon chain length distribution of the alkyl chain of the alkyl alcohol can be obtained from the technical data sheet of the supplier of the constituent alkyl alcohol. Alternatively, the chain length distribution and average molecular weight of the alkyl alcohol used to make the alkyl sulfated anionic surfactant can be determined by methods known in the art. Such methods include capillary gas chromatography with a flame ionization detector on a medium polarity capillary column using hexane as the solvent.

[0037] The alkyl alcohol or blend of alkyl alcohols may be alkoxylated or not. If it is desired that the resulting concentrated surfactant blend contains alkyl alkoxylated sulfate, at least one alkyl alcohol in the alkyl alcohol stream is preferably alkoxylated before the sulfation step. The alkyl alcohols may be a blend of alkyl alcohols that are first blended together and then alkoxylated together to obtain the desired average alkoxylation degree. Alternatively, one or more alcohols may be alkoxylated first, and then the alkoxylated alcohol or alcohol blend may be mixed to achieve the desired average alkoxylation degree. In the first case, a monomodal distribution of alkoxylation is typically achieved, while in the second case, the alkoxylation distribution is typically multimodal.

[0038] If alkoxylated, the alkyl alcohol may have an average degree of alkoxylation of less than 3.5, preferably 0.3 to 2.0, more preferably 0.5 to 0.9, so that the resulting alkyl sulfate anionic surfactant improves the physical stability of the composition of the present invention at low temperatures and improves the foam persistence. However, the average degree of alkoxylation (particularly ethoxylation) of the starting alkyl alcohol is preferably less than 0.5, preferably less than 0.1, and more preferably the starting alkyl alcohol is not alkoxylated, so as to provide improved grease cleaning properties of the resulting alkyl sulfate anionic surfactant. If alkoxylated, ethoxylation is preferred.

[0039] The average degree of alkoxylation is the molar average of the degrees of alkoxylation of all alkyl alcohols (i.e., the molar average degree of alkoxylation). Thus, when calculating the molar average degree of alkoxylation, moles of non-alkoxylated alkyl alcohols are included; Molar average degree of alkoxylation = (x1 * Alkoxylation degree of alkyl alcohol 1 + x2 * Alkoxylation degree of alkyl alcohol 2 + ....) / (x1 + x2 + ....) where x1, x2, ... are the moles of each alkyl (or alkoxy) alcohol in the mixture, and the degree of alkoxylation is the number of alkoxy groups in each alkyl alcohol.

[0040] The preferred alkyl alkoxy alcohols for use in making the alkyl sulfate surfactants are the alkyl ethoxy alcohols.

[0041] Performance including grease cleaning, foaming, low temperature stability, and end product viscosity can be influenced by the breadth of the alkoxylation distribution of the resulting alkoxylated alkyl sulfate anionic surfactant. Through the selection of catalysts and process conditions when making the alkoxylated alkyl alcohol, the alkoxylation distribution can be varied, including its breadth.

[0042] Without being bound by theory, when alkoxylation, for example ethoxylation, of alkyl alcohol is desired, the amount of 1,4-dioxane by-product in alkoxylated, especially ethoxylated alkyl sulfate can be reduced by strictly controlling the process conditions and the composition of the raw materials during both the alkoxylation, especially ethoxylation, and sulfation steps. Based on recent technological advances, further reduction of 1,4-dioxane by-product can be achieved by subsequent stripping, distillation, solvent evaporation, centrifugation, microwave irradiation, molecular sieving, or catalytic or enzymatic decomposition steps. Processes for controlling 1,4-dioxane content in alkoxylated / ethoxylated alkyl sulfate are widely known in the art. Alternatively, control of 1,4-dioxane levels in detergent formulations by adding 1,4-dioxane inhibitors such as 5,6-dihydro-3-(4-morpholinyl)-1-[4-(2-oxo-1-piperidinyl)-phenyl]-2-(1-H)-pyridone, 3-alpha-hydroxy-7-oxo stereoisomeric mixture of cholanic acid, 3-(N-methylamino)-L-alanine and mixtures thereof to formulations containing 1,4-dioxane has also been described in the art.

[0043] The alkyl alcohol has a weight average branching degree of 15% to 50%, preferably 20% to 40%. The use of such branched alkyl alcohols can improve the low temperature stability of the resulting alkyl sulfate surfactant-containing composition and provide the desired grease cleaning performance.

[0044] It has been found that by tightly controlling the C2 branching of the alkyl alcohol, the resulting alkyl sulfate surfactant provides a liquid detergent composition with improved product stability even at low temperatures, without compromising foam persistence and grease cleaning properties, and provides a higher final product viscosity. Furthermore, by limiting the average alkoxylation (particularly ethoxylation) degree of the starting alkyl alcohol to less than 0.5, preferably less than 0.1, and more preferably not alkoxylated, the resulting liquid detergent composition can have reduced viscosity sensitivity to variations in the starting alcohol used to make the alkyl sulfate surfactant.

[0045] Such compositions require less solvent to achieve good physical stability at low temperature.More branched surfactants also result in faster initial foam generation, but typically lower foam durability.The weight average branching described herein has been found to improve low temperature stability, initial foam generation and foam life in liquid detergent compositions containing alkyl sulfate surfactants formed from such alkyl alcohols.

[0046] Thus, the branched alkyl alcohols used to make the alkyl sulfate surfactants can include C2 branched alkyl alcohols and non-C2 branched alkyl alcohols. The weight ratio of non-C2 branched alkyl alcohols to C2 branched alkyl alcohols can be greater than 0.5, preferably 1.0:1 to 5:1, more preferably 2:1 to 4:1.

[0047] C2 branched means that the alkyl branch is a single alkyl branch on the alkyl chain of the alkyl alcohol and is located at the C2 position as measured by counting carbon atoms from the hydroxyl group in the case of a non-alkoxylated alkyl alcohol, or from the alkoxy group furthest from the hydroxyl group in the case of an alkoxylated alkyl alcohol.

[0048] Non-C2 branched means that the alkyl chain contains branches at multiple carbon positions along the alkyl chain backbone, or a single branch group that is present at a branch position on the alkyl chain other than the C2 position.

[0049] The non-C2 branched alkyl alcohols may comprise less than 30% by weight of the non-C2 branched alkyl alcohols, preferably less than 20% by weight, more preferably less than 10% by weight of the C1 branched alkyl alcohols, and most preferably the non-C2 branched alkyl alcohols do not comprise any C1 branched alkyl alcohols.

[0050] The non-C2 branched alkyl alcohol may comprise at least 50% by weight, preferably 60-90% by weight, more preferably 70-80% by weight of the non-C2 branched alkyl alcohol, of isomers containing a single branch at branching positions greater than 2, that is, more than two carbon atoms away from the hydrophilic head group as defined above. The non-C2 alkyl alcohol may comprise 5% to 30% by weight, preferably 7% to 20% by weight, more preferably 10% to 15% by weight of the non-C2 branched alkyl alcohol of multi-branched isomers. The non-C2 alkyl alcohol may comprise 5% to 30% by weight, preferably 7% to 20% by weight, more preferably 10% to 15% by weight of the non-C2 branched alkyl alcohol of cyclic isomers. The acyclic branched groups, if any, may be selected from C1 to C5 alkyl groups, and mixtures thereof.

[0051] The weight average branching degree of the alkyl alcohol mixture can be calculated using the following formula: Weight average branching degree (%) = [(x1 * Weight percent of branched alkyl alcohol 1 in alcohol 1 + x2 * (wt% of branched alkyl alcohol 2 in alcohol 2 + ....) / (x1 + x2 + ....)] * 100 where x1, x2, ... are the weights (in grams) of each alkyl alcohol in the total alkyl alcohol mixture used as starting material prior to (alkoxylation and) sulfation to produce the alkyl(alkoxy)sulfate anionic surfactant. In calculating the weight average degree of branching, the weight of unbranched alkyl alcohols is also included.

[0052] The weight average degree of branching and branching distribution can usually be obtained from the technical data sheet of the surfactant or its constituent alkyl alcohol. Alternatively, branching can be determined through analytical methods known in the art, including capillary gas chromatography with a flame ionization detector on a medium polarity capillary column using hexane as the solvent. The weight average degree of branching and branching distribution are based on the starting alkyl alcohol used to produce the alkyl sulfated anionic surfactant.

[0053] Suitable examples of commercially available alkyl alcohols include those derived from alcohols sold by Shell under the trade name Neodol®, or by Sasol under the trade names Lial®, Isalchem®, and Safol®, or some of the natural alcohols produced by Procter & Gamble Chemicals. The alcohols (and alkoxylated alcohols) can be blended to achieve the desired mole fraction of C12 and C13 chains and the desired C13 / C12 ratio based on the relative fractions of C13 and C12 in the starting alcohol (and the desired degree of alkoxylation) obtained from technical data sheets from the supplier or from analysis using methods known in the art.

[0054] The alkyl alcohols may contain essentially linear or completely linear alkyl chains and are blended with branched alcohols to achieve the desired degree of branching. Preferred sources of naturally occurring alkyl chains include palm kernel and coconut derived alkyl chains, with palm kernel derived alkyl chains being more preferred. The naturally occurring alkyl chains may be fractionated to provide the desired average alkyl chain length as well as to tailor the alkyl chain length distribution. The C12-C14 fraction is often referred to as the mid-cut fraction within the naturally occurring alkyl chains. Alternatively, the essentially linear alkyl chains may be synthetically extracted using the Ziegler process or its derivatives, a process that uses organoaluminum compounds to produce aliphatic alcohols from ethylene. The reaction produces linear primary alcohols with even carbon chains. Again, the C12-C14 alkyl fraction is preferred and may be fractionated from the whole Ziegler alcohol.

[0055] Sulfation In the sulfation process, an alkyl alcohol stream containing at least one alkyl alcohol is sulfated to form an alkyl sulfate stream containing at least one alkyl sulfate. Sulfation involves the formation of a carbon-oxygen-sulfur bond. The resulting acid form of the alkyl sulfate is not hydrolytically stable. Unless neutralized, it will decompose to form sulfuric acid and other chemicals.

[0056] The sulfation of alcohols or alkoxylated alcohols to (alkoxylated) alkyl sulfuric acids has been widely described. Further details of such sulfation processes are given in "Sulf(on)ation Technology in the Detergent Industry" (W. Herman de Groot, Springer-Science+Business Media, BV, 1991, ISBN 978-90-481-4088-6).

[0057] Although a variety of reagents can be used for the sulfation step, sulfur trioxide (SO3) is particularly preferred, at least in part due to its low cost. SO3 is an electrophilic reagent that reacts rapidly with any organic compound that contains an electron donating group. The resulting reaction is highly exothermic. Effective cooling of the reactants is essential, since high temperatures promote side reactions that produce undesirable by-products. Also, precise control of the molar ratio of SO3 to alkyl alcohol is essential, since excess SO3 contributes to side reactions and by-product formation due to its reactivity. Thus, commercial scale sulfation reactions require special equipment and instrumentation that tightly control the molar ratio of SO3 to alkyl alcohol and allow for rapid removal of the heat of reaction.

[0058] The problem of SO3 reactivity has typically been solved by diluting and / or complexing the SO3 to mitigate the reaction rate. Commercially available diluents or complexing agents include ammonia (sulfamic acid), hydrochloric acid (chlorosulfonic acid), and dry air (air / SO3 membrane sulfation). Control of the ratio of SO3 to alkyl alcohol can be used to achieve improved product quality with the use of any of these reagents.

[0059] Air / SO3 membrane sulfation processes are typically carried out using membrane reactors such as annular falling film reactors, such as the "Chemithon" reactor, or multitubular membrane reactors, such as the "Ballestra" reactor. In such processes, the SO3 is first diluted with dry air. Such air / SO3 sulfation processes are direct processes in which the SO3 gas is diluted with very dry air and reacted directly with the alkyl alcohol feedstock. The reaction of gaseous SO3 with the alkyl alcohol is rapid and stoichiometric. Such processes are complicated by the possibility of side reactions, however, with strict process control very high purity alkyl sulfate surfactants can be achieved.

[0060] SO3 can be obtained by burning molten sulfur in excess oxygen to form SO2, which is then catalytically oxidized to SO3, for example at temperatures between 400°C and 470°C. The conversion of sulfur to SO2 is typically at least 95%, preferably at least 99%, more preferably at least >99.9% complete. Oxygen can be provided by ambient air that has been pre-dried to remove most of the water by condensation and subsequent drying with a desiccant until the ambient air has a maximum dew point of -60°C, preferably <-70°C. Considering the exothermic nature of the sulfur combustion reaction, the SO2 / air stream is cooled in an indirect air cooler before converting SO2 to SO3 by catalytic oxidation. The catalytic oxidation is typically carried out using at least one, preferably three to four, catalytic beds. An example of such a catalytic converter includes a converter tower packed with four packed beds of V2O5 catalyst on a silica support. Considering the exothermic nature of the oxidation of SO2 to SO3, inter-cooling of the resulting process gas is carried out between the various beds via an indirect air cooler, such as a vertical air-cooled shell-and-tube heat exchanger. Despite the atmospheric pre-drying step, some sulfuric / oleum mist still condenses, which is removed through a demister such as a Brink filter prior to the sulfation step. To ensure sufficient mist removal, the gas stream is cooled to at least 60°C at this point in the process, but most preferably the gas stream is cooled to a temperature of 30-55°C.

[0061] In the air / SO3 membrane sulfation process, the sulfation step is typically carried out in a liquid-gas interface reactor, preferably a falling film reactor. Suitable falling film reactors include annular gap falling film ("Chemithon") reactors, (multi)tubular ("Ballestra") reactors, etc.

[0062] The alkyl alcohol or a blend of alkyl alcohols is converted to alkyl sulfates via reaction with SO3 in a falling film reactor. Given the exothermic nature of the sulfonation reaction, cooling is again required after separating the air / gas from the liquid stream. Ideally, the reaction mixture is maintained at a temperature between 15°C and 50°C, preferably between 30°C and 40°C, at the reactor outlet.

[0063] The atmosphere / gas can be separated from the liquid using a liquid separator. If the separation does not remove enough gas from the liquid mixture, an additional degassing step can be performed, for example by using a "Fryma" rotating disk degasser.

[0064] The exhaust gas typically contains small amounts of unconverted SO2, unreacted SO3, and some entrained organic acids. Organic aerosols and trace amounts of SO3 / H2SO4 droplets are typically separated from the exhaust gas stream in an electrostatic precipitator, and gaseous SO2 gas is typically scrubbed from the process atmosphere in a scrubber using a dilute caustic solution.

[0065] To minimize the formation of sulfuric acid and maintain a low ionic strength, the alkyl alcohol stream fed to the sulfation reaction preferably contains less than 0.1%, preferably less than 0.05%, and more preferably is water-free.

[0066] The sulfation reaction typically results in a conversion of at least 90% by weight of the starting alkyl alcohol, preferably at least 95% by weight, more preferably at least 97% by weight. The presence of sulfuric acid in the liquid stream after sulfation is typically less than 1% by weight of the total liquid stream, preferably less than 0.75% by weight, more preferably less than 0.5% by weight.

[0067] Neutralization Considering the susceptibility of protonated alkyl sulfate to rehydrolysis to the starting alkyl alcohol, the neutralization step is necessary as a result. Without neutralization, rehydrolysis of the alkyl sulfate results in a reduction in the alkyl sulfated anionic surfactant content in the resulting concentrated surfactant blend, and an increase in the sulfuric acid content, which results in discoloration of the concentrated surfactant blend and the liquid detergent compositions made with the concentrated surfactant blend.

[0068] In the present process, a neutralization stream is provided that includes at least one neutralizing agent. During or after the neutralization step, the neutralizing agent may be added at a concentration that provides a resulting concentrated surfactant blend having a pH of from 7.1 to 10, preferably from 7.3 to 9.5, more preferably from 7.5 to 9.0, measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C.

[0069] Too low a pH may result in rehydrolysis of alkyl sulfated anionic surfactants, while too high a pH typically complicates the conversion of concentrated surfactant blends into final detergent product compositions, for example requiring a significant amount of acid to return the pH to the target final product pH. In addition, too high a pH may result in the generation of 1,4-dioxane over time, as well as the addition of more neutralizing agent, resulting in a corresponding increase in salt concentration in the concentrated surfactant blend. Concentrated surfactant blends containing high salt concentrations are more difficult to formulate into detergent compositions, resulting in reduced low temperature stability, as well as increased viscosity upon initial dissolution with water, which correspondingly slows the dissolution of the product.

[0070] The neutralizing agent is an alkali. Additional neutralizing agent can be added after the neutralization step to adjust the pH to a desired level. Suitable alkalis can be selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonia, monoethanolamine, diethanolamine, triethanolamine, and mixtures thereof, with sodium hydroxide being most preferred. Alternatively or in addition, other alkalis can be added as part of the neutralization step. Particularly suitable other alkalis are those that can be added to the resulting liquid detergent composition to improve performance. In particular, amines, especially cyclic polyamines with amine functional groups that aid in cleaning, as described below.

[0071] The neutralization step should be completed in less than 10 minutes, preferably less than 5 minutes, and most preferably less than 2 minutes after the sulfation step is completed.

[0072] Neutralization can be carried out by any suitable means, including in a batch reactor or by combining the alkyl sulfuric acid stream with the neutralization stream using a high shear mixer. In a preferred process, a loop reactor can be used. The loop reactor is a continuous tube or pipe, typically stainless steel, with the outlet of a recirculation pump connected to its inlet. The reactants are fed into the loop, where neutralization occurs, and an at least partially neutralized mixture is removed from the loop.

[0073] Therefore, the loop reactor typically includes a circulation pump, a breaker or high shear mixer, and a heat exchanger due to the exothermic nature of the neutralization reaction. Efficient mixing of the alkyl sulfate stream with the neutralization stream results in an instantaneous reaction, avoiding undesirable decomposition reactions in isolated spots and pH trends that arise during the neutralization process. Therefore, a high shear mixer is typically used, taking into account the high viscosity of the resulting paste, especially at low shear rates.

[0074] Because the neutralization reaction is exothermic, the mixture can be continuously cooled using a heat exchanger, such as a plate and frame heat exchanger, to achieve a temperature for the alkyl sulfate stream after neutralization below 70°C, preferably below 60°C, and most preferably in the range of 20-40°C.

[0075] Water or organic solvents can be added to control viscosity or improve homogenization during the neutralization step. Suitable organic solvents include C1-C4 alcohols, especially ethanol. Such organic solvents can be added as a separate stream during the neutralization step, or as part of the alkyl alcohol stream, or as part of the neutralization stream. Water can be added as a separate stream during the neutralization step, or as part of the neutralization stream.

[0076] Water may be added at a concentration such that the resulting concentrated surfactant blend contains water at a concentration of 20% to 50%, preferably 25% to 45%, more preferably 30% to 40% by weight of the concentrated surfactant blend. The concentration of water may be measured using any suitable means, such as via Karl Fischer titration.

[0077] The neutralization stream may contain water at a concentration of 35% to 80% by weight of the neutralization stream, preferably 45% to 75% by weight, and more preferably 55% to 65% by weight.

[0078] A buffering surfactant is preferably added during the neutralization step to ensure that the resulting mixture quickly reaches the desired pH to avoid the aforementioned hydrolysis.

[0079] The neutralization stream may contain other optional ingredients, such as non-ionic surfactants, polymers, and peroxides, such as those described below, and mixtures thereof.

[0080] After the neutralization step, the resulting neutralized surfactant paste can be transported to a storage tank via a transfer pump.

[0081] Buffer Surfactant: The buffer surfactant is preferably added as a separate buffer stream during the neutralization step, but is preferably added as part of the neutralization stream. Alternatively, the buffer surfactant can be added before the neutralization step. The alkyl sulfate and buffer surfactant can be combined in a weight ratio of alkyl sulfate to buffer surfactant of 10:1 to 1:1, preferably 8:1 to 2:1, more preferably 6:1 to 3:1.

[0082] The buffering surfactant reduces pH fluctuations and pH trends when small amounts of acid are added or formed, for example, through hydrolysis of alkyl sulfate surfactants, or even through absorption of carbon dioxide from the atmosphere. As a result, the resulting concentrated surfactant blend can be stored at a lower pH, resulting in less formation of 1,4-dioxane and less salts being present in detergent compositions containing the concentrated surfactant blend.

[0083] The buffer surfactant is an amphoteric surfactant, a zwitterionic surfactant, or a mixture thereof. Suitable buffer surfactants can be selected from the group consisting of amine oxide surfactants, betaine surfactants, and mixtures thereof, preferably amine oxide surfactants, more preferably C10-16 dimethylamine oxide surfactants. C12-14 dimethylamine oxide (lauryl dimethylamine oxide) is particularly preferred. Such buffer surfactants also contribute to the performance of the resulting liquid hand dishwashing detergent. In addition, the buffer surfactant results in the concentrated surfactant blend formed by the process described herein having reduced viscosity, especially when amine oxide surfactants are used as the buffer surfactant.

[0084] The buffer surfactant may be added at a concentration such that the resulting concentrated surfactant blend contains buffer surfactant at a concentration of 1.0% to 25% by weight of the concentrated surfactant blend, preferably 5.0% to 20% by weight, and more preferably 10% to 15% by weight.

[0085] Suitable amine oxide surfactants may be linear or branched, with linear being preferred. Suitable linear amine oxides are typically water-soluble and are characterized by the formula R1-N(R2)(R3)O, where R1 is a C8-18 alkyl and the R2 and R3 moieties are selected from the group consisting of C1-3 alkyl groups, C1-3 hydroxyalkyl groups, and mixtures thereof. For example, R2 and R3 may be selected from the group consisting of methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl, and 3-hydroxypropyl, and mixtures thereof, with one or both of R2 and R3 being preferably methyl. Linear amine oxide surfactants may include, in particular, linear C10-C18 alkyl dimethyl amine oxides and linear C8-C12 alkoxyethyl dihydroxyethyl amine oxides.

[0086] Preferably, the amine oxide surfactant is selected from the group consisting of alkyl dimethylamine oxide, alkyl amidopropyl dimethylamine oxide, and mixtures thereof. Particularly preferred are alkyl dimethylamine oxides such as C8-18 alkyl dimethylamine oxide or C10-16 alkyl dimethylamine oxide (such as cocodimethylamine oxide). Suitable alkyl dimethylamine oxides include C10 alkyl dimethylamine oxide surfactants, C10-12 alkyl dimethylamine oxide surfactants, C12-C14 alkyl dimethylamine oxide surfactants, and mixtures thereof. Particularly preferred are C12-C14 alkyl dimethylamine oxides, C12-14 alkyl amidopropyl amine oxides, and mixtures thereof.

[0087] Alternative suitable amine oxide surfactants include mid-branched amine oxide surfactants. As used herein, "mid-branched" means that the amine oxide has one alkyl moiety with n1 carbon atoms, and one alkyl branch in the alkyl moiety has n2 carbon atoms. The alkyl branch is located on the alpha carbon from the nitrogen on the alkyl moiety. This type of branching of amine oxides is also known in the art as internal amine oxides. The sum of n1 and n2 may be 10-24, preferably 12-20, more preferably 10-16 carbon atoms. The number of carbon atoms in one alkyl moiety (n1) is preferably the same or similar to the number of carbon atoms in one alkyl branch (n2), so that the one alkyl moiety and the one alkyl branch are symmetrical. As used herein, "symmetrical" means that in at least 50% by weight, more preferably at least 75% to 100% by weight of the mid-branched amine oxides used herein, |n1-n2| is 5 or less, preferably 4, most preferably 0-4 carbon atoms. The amine oxide further comprises two moieties independently selected from a C1-3 alkyl, a C1-3 hydroxyalkyl group, or a polyethylene oxide group containing an average of about 1 to about 3 ethylene oxide groups. Preferably, the two moieties are selected from a C1-3 alkyl, and more preferably, both are selected as a C1 alkyl.

[0088] Alternatively, the amine oxide surfactant may be a mixture of amine oxides, including a mixture of low cut and mid cut amine oxides. Thus, the amine oxide of the composition of the present invention may be: a) about 10% to about 45% by weight of an amine oxide of a low cut amine oxide of formula R1R2R3AO, where R1 and R2 are independently selected from hydrogen, C1-C4 alkyl, or mixtures thereof, and R3 is selected from C10 alkyl and mixtures thereof; b) 55% to 90% by weight of the amine oxide, a mid-cut amine oxide of formula R4R5R6AO, where R4 and R5 are independently selected from hydrogen, C1-C4 alkyl, or mixtures thereof, and R6 is selected from C12-C16 alkyl, or mixtures thereof.

[0089] In the low cut amine oxides preferred for use herein, R3 is n-decyl, and preferably R1 and R2 are both methyl. In the mid cut amine oxides of formula R4R5R6AO, preferably R4 and R5 are both methyl.

[0090] Preferably, the amine oxide comprises less than about 5% by weight of the amine oxide, more preferably less than 3% by weight of the amine oxide of formula R7R8R9AO, where R7 and R8 are selected from hydrogen, C1-C4 alkyl, and mixtures thereof, and R9 is selected from C8 alkyl, and mixtures thereof. By limiting the amount of amine oxide of formula R7R8R9AO, both physical stability and foam persistence are improved.

[0091] Suitable zwitterionic surfactants include betaine surfactants, including alkyl betaines, alkyl amido betaines, amido azolinium betaines, sulfo betaines (INCI sultaines), and phospho betaines, preferably satisfying formula (I): R 1 -[CO-X(CH2) n ] x -N + (R 2 )(R3)-(CH2) m -[CH(OH)-CH2] y -Y - In formula (I), R1 is selected from the group consisting of saturated or unsaturated C6-22 alkyl residues, preferably C8-18 alkyl residues, more preferably saturated C10-16 alkyl residues, and most preferably saturated C12-14 alkyl residues; X is selected from the group consisting of NH, NR4 (wherein R4 is a C1-4 alkyl residue), O, and S; n is an integer of 1 to 10, preferably 2 to 5, and more preferably 3; x is 0 or 1, preferably 1; R2 and R3 are independently selected from the group consisting of C1-4 alkyl residues, substituted hydroxy such as hydroxyethyl, and mixtures thereof, preferably both R2 and R3 are methyl; m is an integer from 1 to 4, preferably 1, 2, or 3; y is 0 or 1; Y is selected from the group consisting of COO, SO3, OPO(OR5)O, or P(O)(OR5)O, where R5 is H or a C1-4 alkyl residue.

[0092] Preferred betaines are the alkyl betaines of formula (Ia), the alkyl amidopropyl betaines of formula (Ib), the sulfo betaines of formula (Ic) and the amido sulfo betaines of formula (Id), R 1 -N + (CH3)2-CH2COO - (Ia) R 1 -CO-NH-(CH2)3-N + (CH3)2-CH2COO - (Ib) R 1 -N + (CH3)2-CH2CH(OH)CH2SO3 - (I C) R 1 -CO-NH-(CH2)3-N + (CH3)2-CH2CH(OH)CH2SO3 - (Id) In the formula, R1 has the same meaning as in formula (I). Particularly preferred are carbobetaines of formula (Ia) and (Ib) [i.e., in formula (I), Y- is COO-], and more preferred are alkylamidobetaines of formula (Ib).

[0093] Suitable betaines may be selected from the group consisting of capryl / capramidopropyl betaine, cetyl betaine, cetylamidopropyl betaine, cocamidoethyl betaine, cocamidopropyl betaine, coco betaine, decyl betaine, decylamidopropyl betaine, hydrogenated tallow betaine / amidopropyl betaine, isostearamidopropyl betaine, lauramidopropyl betaine, lauryl betaine, myristyl amidopropyl betaine, myristyl betaine, oleadopropyl betaine, oleyl betaine, palmamidopropyl betaine, palmitamidopropyl betaine, palm kernelamidopropyl betaine, stearamidopropyl betaine, stearyl betaine, tallowamidopropyl betaine, tallow betaine, undecylenamidopropyl betaine, undecyl betaine, and mixtures thereof, or [named according to INCI]. Preferred betaines are selected from the group consisting of cocamidopropyl betaine, coco betaine, lauramidopropyl betaine, lauryl betaine, myristyl amidopropyl betaine, myristyl betaine, and mixtures thereof. Cocamidopropyl betaine is particularly preferred.

[0094] In the neutralization step, the at least one alkyl sulfate and the buffer surfactant may be combined in a weight ratio of 10:1 to 1:1, preferably 8:1 to 2:1, and more preferably 6:1 to 3:1.

[0095] Thus, the concentration of unreacted alkyl alcohol and / or alkoxylated alcohol is preferably less than 3% by weight, more preferably less than 2.5% by weight, and most preferably less than 2% by weight of the starting alkyl sulfate at the start of the neutralization step. The amount of unreacted alkyl (alkoxylated) alcohol can be determined by GC analysis (after neutralization of the alkyl sulfate).

[0096] A buffer surfactant may be added to the stream further comprising peroxide, particularly when an amine oxide is used as the buffer surfactant. The peroxide may be present such that the buffer surfactant-containing stream has a residual peroxide concentration of 5.0 ppm to 300 ppm, preferably 40 ppm to 80 ppm, per part by weight of buffer surfactant. When the concentrated surfactant blend comprises an ethoxylated alkyl sulfate surfactant, the presence of peroxide is believed to further limit the formation and growth of 1,4-dioxane within the concentrated surfactant blend formed by the present process.

[0097] Optional Further Steps If desired, for example, to simplify the preparation of the final liquid detergent composition, before, during or after neutralization, auxiliary components such as those described below can also be added.Other optional components include water, organic solvent, pH adjuster, additional surfactant, polymer, amine, preservative, and mixtures thereof.Suitable additional surfactants include additional anionic surfactants, nonionic surfactants, and mixtures thereof.

[0098] Concentrated surfactant blend containing alkyl sulfates The resulting concentrated surfactant blend comprises 30% to 70%, preferably 40% to 60%, more preferably 45% to 55% by weight of the resulting concentrated surfactant blend of an alkyl sulfated anionic surfactant, and 1.0% to 25%, preferably 5.0% to 20%, more preferably 10% to 15% by weight of the resulting concentrated surfactant blend of a buffer surfactant. The concentrated surfactant blend comprises an alkyl sulfated anionic surfactant, the alkyl sulfated anionic surfactant having an average degree of alkoxylation of less than 0.5, preferably less than 0.1, more preferably not alkoxylated. If alkoxylated, the alkoxylation is preferably ethoxylated.

[0099] The buffering surfactant buffers the pH of the concentrated surfactant blend without the need to introduce additional salts into the blend. Thus, the concentrated surfactant blend resists changes in pH due to the addition or formation of acids (or bases). The resulting buffering, for example, reduces the alkyl sulfate concentration upon aging in contact with the atmosphere, but reduces the by-products (e.g., HSO4) that cause browning of the concentrated surfactant blend. - The buffer also reduces the risk of alkyl sulfate surfactant hydrolysis due to a drop in pH, which also results in the formation of alkyl sulfate surfactants. Furthermore, a higher pH is required for concentrated surfactant blends to avoid a drop in pH over time to a level where, without buffering, alkyl sulfate surfactant hydrolysis occurs fairly quickly. The need to add additional alkali results in a higher ionic strength of the non-buffered concentrated surfactant blends. This results in reduced processability of the concentrated surfactant blends, as well as reduced dispersibility upon dilution, reduced viscosity, and reduced foaming and foam persistence of compositions containing such non-buffered concentrated surfactant blends.

[0100] A buffer for a particular application must be effective at the desired pH and must also provide sufficient buffering capacity to maintain the desired pH, if necessary. To inhibit hydrolysis and minimize the formation of 1,4-dioxane, the resulting concentrated surfactant blends formed by the processes described herein preferably have a buffer window of pH between 7.0 and 7.8.

[0101] A measure of the effectiveness of a buffer system is provided by reserve alkalinity, which is essentially the ability of the composition to neutralize acidic residues formed in the composition, such as by hydrolysis of the alkyl sulfate surfactant. The buffer surfactant is added at a concentration that provides the resulting concentrated surfactant blend, using the methods described herein, with a reserve alkalinity of greater than 0.02, preferably between 0.04 and 0.50, and more preferably between 0.06 and 0.30, when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20°C.

[0102] The alkyl sulfated anionic surfactant and the buffer surfactant may be present in the concentrated surfactant mixture in a weight ratio of from 10:1 to 1:1, preferably from 8:1 to 2:1, more preferably from 6:1 to 3:1.

[0103] It has been found that the present process utilizing buffered surfactants allows for a lower pH of the concentrated surfactant blend. As a result, a lower concentration of 1,4-dioxane is present in the concentrated surfactant blend. Furthermore, the resulting alkyl sulfate-containing concentrated surfactant blend exhibits a lower rate of increase in 1,4-dioxane by-product concentration due to degradation. Thus, the dioxane concentration in the concentrated surfactant blend formed by the process of the present invention can be less than 40 ppm, preferably less than 30 ppm, and most preferably less than 15 ppm.

[0104] The concentrated surfactant blend can include additional surfactants.Suitable additional surfactants include additional anionic surfactants, such as sulfonate anionic surfactants, such as HLAS, or sulfosuccinate anionic surfactants.However, in a preferred process, the amount of such additional anionic surfactants is kept low.In a more preferred process, no additional anionic surfactants are added.Thus, the concentrated surfactant blend can include at least 70% by weight of anionic surfactant, preferably at least 85% by weight, more preferably 100% by weight of alkyl sulfated anionic surfactant.The concentrated surfactant blend preferably does not include fatty acid or its salt, because such fatty acid hinders foam generation.

[0105] Suitable additional surfactants include non-ionic surfactants. The concentrated surfactant blend may further comprise a non-ionic surfactant. Suitable non-ionic surfactants include alkoxylated alcohol non-ionic surfactants, alkyl polyglucoside non-ionic surfactants, and mixtures thereof.

[0106] The concentrated surfactant blend may comprise from 1% to 25%, preferably from 1.25% to 20%, more preferably from 1.5% to 15%, and most preferably from 1.5% to 5% of an alkoxylated alcohol nonionic surfactant by weight of the total surfactant in the concentrated surfactant blend.

[0107] Preferably, the alkoxylated alcohol nonionic surfactant is a linear or branched primary or secondary alkyl alkoxylated nonionic surfactant, preferably an alkyl ethoxylated nonionic surfactant, preferably containing an average of 9 to 15, preferably 10 to 14 carbon atoms in its alkyl chain and an average of 5 to 12, preferably 6 to 10, most preferably 7 to 8 units of ethylene oxide per mole of alcohol.

[0108] The concentrated surfactant blend may include an alkyl polyglucoside ("APG") surfactant. The addition of an alkyl polyglucoside surfactant has been found to improve foaming over comparable nonionic surfactants such as alkyl ethoxylated nonionic surfactants. When present, the alkyl polyglucoside may be present in the concentrated surfactant blend at a concentration of 0.5% to 20%, preferably 0.75% to 15%, more preferably 1% to 10%, and most preferably 1% to 5% by weight of the total surfactant in the concentrated surfactant blend. Preferably, the alkyl polyglucoside surfactant is a C8-C16 alkyl polyglucoside surfactant, preferably a C8-C14 alkyl polyglucoside surfactant. The alkyl polyglucoside preferably has an average degree of polymerization of 0.1 to 3, more preferably 0.5 to 2.5, and even more preferably 1 to 2. Most preferably, the alkyl polyglucoside surfactant has an average alkyl carbon chain length of 10 to 16, preferably 10 to 14, most preferably 12 to 14, and an average degree of polymerization of 0.5 to 2.5, preferably 1 to 2, most preferably 1.2 to 1.6.

[0109] C8-C16 alkyl polyglucosides are commercially available from several sources (e.g., Simusol® surfactants from Seppic Corporation, and Glucopon® 600 CSUP, Glucopon® 650 EC, Glucopon® 600 CSUP / MB, and Glucopon® 650 EC / MB from BASF Corporation).

[0110] The resulting concentrated surfactant blend can have a pH of 7.1 to 10, preferably 7.3 to 9.5, more preferably 7.5 to 9.0, measured as a 10 wt. % solution of the concentrated surfactant blend in demineralized water at 20° C. A pH that is too low can result in rehydrolysis of alkyl sulfates, while a pH that is too high typically complicates the conversion of the concentrated surfactant blend into a final detergent product composition, for example requiring significant amounts of acid to return the pH to the target final product pH. In addition, a pH that is too high can result in the generation of 1,4-dioxane over time, plus the need to add more neutralizing agent, resulting in a corresponding increase in salt concentration in the concentrated surfactant blend. Concentrated surfactant blends containing high salt concentrations are more difficult to formulate into detergent compositions, leading to reduced low temperature stability as well as increased viscosity upon initial dissolution with water, slowing the dissolution of the product.

[0111] The concentrated surfactant mixture can be Newtonian or non-Newtonian, preferably Newtonian. The surfactant blend is -1 The viscosity, measured at a shear rate of 5,000 mPa·s to 25,000 mPa·s, preferably 7,500 mPa·s to 20,000 mPa·s, and most preferably 10,000 mPa·s to 15,000 mPa·s, is measured at a shear rate of 5,000 mPa·s to 25,000 mPa·s, and at a temperature of 20° C.

[0112] The concentrated surfactant blend may have a flow index of 0.1 to 1.0, preferably 0.2 to 0.5, more preferably 0.2 to 0.4. The concentrated surfactant blend may have a yield stress of 5.0 Pa to 30 Pa, preferably 10 Pa to 25 Pa, more preferably 15 Pa to 20 Pa. The aforementioned flow index and yield stress result in improved processability of the concentrated surfactant blend.

[0113] The melting point of the concentrated surfactant blend is preferably below 20° C., more preferably below 15° C., and most preferably below 10° C., so that the concentrated surfactant blend can be stored at ambient temperature and does not require heating to be processed into a detergent composition. The melting point may be measured using differential scanning calorimetry (DSC).

[0114] The concentrated surfactant blend has a viscosity of 500 kg / m2, measured at a temperature of 20°C. 3 ~1,500kg / m 3 , preferably 750 kg / m 3 ~1,250kg / m 3 , more preferably 1,000 kg / m 3 ~1,100kg / m 3 The density may range from 0.01 to 0.05 μm. The density may be measured using any suitable means, such as using a pycnometer.

[0115] Liquid hand dishwashing composition The concentrated surfactant blends described herein can be used to make liquid detergent compositions, particularly liquid hand dishwashing detergent compositions.

[0116] As used herein, the terms "dishware" and "tableware" include, by way of non-limiting examples, cookware and tableware made from ceramic, china, metal, glass, plastic (e.g., polyethylene, polypropylene, polystyrene, etc.), and wood.

[0117] The cleaning composition is a liquid cleaning composition, preferably a liquid hand dishwashing cleaning composition, and is therefore in liquid form. The liquid cleaning composition is preferably an aqueous cleaning composition. Thus, the composition may contain 50% to 85% by weight, preferably 50% to 75% by weight of water by weight of the total composition.

[0118] The liquid cleaning composition has a pH of greater than 6.0, or from 6.0 to 12.0, preferably from 7.0 to 11.0, more preferably from 8.0 to 10.0, measured as a 10% aqueous solution in demineralised water at 20°C.

[0119] When the pH is above pH 7.0, the reserve alkalinity may be 0.1 to 1.0, more preferably 0.1 to 0.5. Reserve alkalinity is expressed herein as grams (NaOH) / 100 ml (composition) required to titrate the product from pH 7.0 to the pH of the final composition. This pH and reserve alkalinity further contribute to the cleaning of stubborn food soils.

[0120] The liquid cleaning compositions of the present invention may be Newtonian or non-Newtonian, but are preferably Newtonian. Preferably, the compositions have a viscosity of from 10 mPa·s to 10,000 mPa·s, preferably from 100 mPa·s to 5,000 mPa·s, more preferably from 300 mPa·s to 2,000 mPa·s, or most preferably from 500 mPa·s to 1,500 mPa·s, or alternatively a combination thereof. Viscosity is measured at 20° C. using a Brookfield RT viscometer with spindle 31 and the RPM of the viscometer adjusted to achieve 40% to 60% torque.

[0121] The liquid cleaning composition may include a concentrated surfactant blend and any additional surfactants such that the composition comprises from 5.0% to 50%, preferably from 6.0% to 40%, and most preferably from 15% to 35% of the surfactant system by weight of the total composition.

[0122] The liquid hand dishwashing detergent composition comprises an anionic surfactant contained in the concentrated surfactant blend used to make the detergent composition. Preferably, the liquid hand dishwashing detergent composition does not comprise any additional anionic surfactant.

[0123] The liquid hand dishwashing detergent composition comprises a co-surfactant that comprises or consists of a buffer surfactant that is contained in the concentrated surfactant blend used to make the detergent composition. In addition to the co-surfactant that is contained in the concentrated surfactant blend, additional co-surfactants can be added. The liquid hand dishwashing detergent composition may also comprise a non-ionic surfactant. Suitable non-ionic surfactants include alkoxylated alcohol non-ionic surfactants, alkyl polyglucoside non-ionic surfactants, and mixtures thereof, as described above. Such non-ionic surfactants can be added as part of the concentrated surfactant blend used to make the detergent composition, or can be added separately in addition to the concentrated surfactant blend, or both.

[0124] The composition can include additional components such as those selected from amphiphilic alkoxylated polyalkyleneimines, cyclic polyamines, triblock copolymers, inorganic monovalent, divalent, or trivalent salts, hydrotropes, organic solvents, other adjunct components such as those described herein, and mixtures thereof. Such components can be added as part of the surfactant blend or can be added separately in addition to the surfactant blend.

[0125] Amphiphilic alkoxylated polyalkyleneimines: The composition of the present invention may further comprise 0.05% to 2% by weight, preferably 0.07% to 1% by weight of the total composition, of an amphiphilic polymer. Suitable amphiphilic polymers may be selected from the group consisting of amphiphilic alkoxylated polyalkyleneimines and mixtures thereof. Amphiphilic alkoxylated polyalkyleneimine polymers have been found to improve grease removal.

[0126] Preferred amphiphilic alkoxylated polyethyleneimine polymers have the general structure of formula (I):

[0127] [ka] wherein the polyethyleneimine backbone has a weight average molecular weight of 600, n in formula (I) is an average of 10, m in formula (I) is an average of 7, and R in formula (I) is selected from hydrogen, C1-C4 alkyl, and mixtures thereof, preferably hydrogen. The permanent degree of quaternization in formula (I) may be 0%-22% of the nitrogen atoms of the polyethyleneimine backbone. The molecular weight of this amphiphilic alkoxylated polyethyleneimine polymer is preferably 10,000-15,000 Da.

[0128] More preferably, the amphiphilic alkoxylated polyethyleneimine polymer has the general structure of formula (I), but the polyethyleneimine backbone has a weight average molecular weight of 600 Da, n in formula (I) is an average of 24, m in formula (I) is an average of 16, and R in formula (I) is selected from hydrogen, C1-C4 alkyl, and mixtures thereof, preferably hydrogen. The permanent degree of quaternization of formula (I) may be 0%-22% of the nitrogen atoms of the polyethyleneimine backbone, preferably 0%. The molecular weight of this amphiphilic alkoxylated polyethyleneimine polymer is preferably 25,000-30,000, most preferably 28,000 Da.

[0129] Amphiphilic alkoxylated polyethyleneimine polymers can be made by the methods described in more detail in WO 2007 / 135645.

[0130] Cyclic Polyamines The composition may include a cyclic polyamine having an amine functionality to aid in cleaning. The composition of the present invention preferably comprises from 0.1% to 3%, more preferably from 0.2% to 2%, especially from 0.5% to 1% of a cyclic polyamine by weight of the composition.

[0131] Cyclic polyamines have at least two primary amine functional groups. The primary amine may be present at any position in the cyclic amine, but it has been found that better performance is obtained from the standpoint of grease cleaning when the primary amine is present at the 1,3 positions. It has also been found that cyclic amines in which one of the substituents is -CH3 and the remaining are H provide improved grease cleaning performance.

[0132] Thus, the most preferred cyclic polyamines for use in the cleaning compositions of the present invention are those selected from the group consisting of 2-methylcyclohexane-1,3-diamine, 4-methylcyclohexane-1,3-diamine, and mixtures thereof. These particular cyclic polyamines, when formulated with the surfactant system of the compositions of the present invention, function to improve the foam and grease cleaning profile throughout the dishwashing process.

[0133] Suitable cyclic polyamines may be supplied by BASF under the trade name Baxxodur, with Baxxodur ECX-210 being particularly preferred.

[0134] A combination of a cyclic polyamine and magnesium sulfate is particularly preferred. Thus, the composition may further comprise magnesium sulfate at a concentration of 0.001% to 2.0% by weight of the composition, preferably 0.005% to 1.0% by weight, more preferably 0.01% to 0.5% by weight.

[0135] Triblock Copolymer The composition of the present invention may comprise a triblock copolymer. The triblock copolymer may be present at a concentration of 0.1% to 10%, preferably 0.5% to 7.5%, more preferably 1% to 5% by weight of the total composition. Suitable triblock copolymers include alkylene oxide triblock copolymers, defined as triblock copolymers having alkylene oxide moieties according to formula (I): (EO)x(PO)y(EO)x, where EO represents ethylene oxide and each x represents the number of EO units in the EO block. Each x may independently be on average 5 to 50, preferably 10 to 40, more preferably 10 to 30. Preferably, x is the same for both EO blocks, where "same" means that the difference in x between the two EO blocks is within a maximum of 2 units, preferably within a maximum of 1 unit, more preferably both x are the same number of units. PO represents propylene oxide and y represents the number of PO units in the PO block. Each y can be set to an average of 28 to 60, preferably 30 to 55, and more preferably 30 to 48.

[0136] Preferably, the ratio of y to each x in the triblock copolymer is 3:1 to 2:1. The ratio of y to the average x of the two EO blocks in the triblock copolymer is preferably 3:1 to 2:1. Preferably, the triblock copolymer has an average weight percentage of total EO that is 30% to 50% by weight of the triblock copolymer. Preferably, the triblock copolymer has an average weight percentage of total PO that is 50% to 70% by weight of the triblock copolymer. It is understood that the average total weight percentage of EO and PO for the triblock copolymer sums to 100%. The triblock copolymer can have an average molecular weight of 2060 to 7880, preferably 2620 to 6710, more preferably 2620 to 5430, most preferably 2800 to 4700. The average molecular weight is determined using 1H NMR spectroscopy (see Thermo scientific application note No. AN52907).

[0137] Triblock copolymers have the basic structure ABA, where A and B are different homopolymeric and / or monomeric units. In this case, A is ethylene oxide (EO) and B is propylene oxide (PO). Those skilled in the art will recognize that the phrase "block copolymer" is synonymous with this definition of "block polymer."

[0138] Triblock copolymers according to formula (I) having specific EO / PO / EO configurations and respective homopolymer lengths have been found to enhance the foam persistence performance of liquid hand dishwashing detergent compositions in the presence of greasy soils and / or foam consistency throughout dilution in the cleaning process.

[0139] Suitable EO-PO-EO triblock copolymers are commercially available from BASF, e.g., under the Pluronic® PE series, and from Dow Chemical Company, e.g., under the Tergitol® L series. Particularly preferred triblock copolymers from BASF are sold under the trade names Pluronic® PE6400 (MW about 2900, about 40 wt. % EO) and Pluronic® PE9400 (MW about 4600, 40 wt. % EO). Particularly preferred triblock copolymers from Dow Chemical Company are sold under the trade name Tergitol® L64 (MW about 2700, about 40 wt. % EO).

[0140] Preferred triblock copolymers are readily biodegradable under aerobic conditions.

[0141] The compositions of the present invention may further comprise at least one active agent selected from the group consisting of salts, hydrotropes, organic solvents, and mixtures thereof.

[0142] salt: The composition of the present invention may contain from 0.05% to 2% by weight of the total composition, preferably from 0.1% to 1.5% by weight, or more preferably from 0.5% to 1% by weight of a salt, preferably a monovalent or divalent inorganic salt or mixtures thereof, more preferably selected from sodium chloride, sodium sulfate and mixtures thereof, with sodium chloride being most preferred.

[0143] Hydrotropes: The compositions of the present invention may comprise from 0.1% to 10%, or preferably from 0.5% to 10%, or more preferably from 1% to 10% by weight of the total composition of a hydrotrope or mixture thereof, preferably sodium cumene sulfonate.

[0144] Organic solvents: The composition may contain 0.1% to 10% by weight of the organic solvent, or preferably 0.5% to 10% by weight, or more preferably 1% to 10% by weight of the total composition. Suitable organic solvents include organic solvents selected from the group consisting of alcohols, glycols, glycol ethers, and mixtures thereof, preferably alcohols, glycols, and mixtures thereof. Ethanol is a preferred alcohol. Polyalkylene glycols, especially polypropylene glycol (PPG), are preferred glycols. The polypropylene glycol may have a molecular weight of 400 to 3000, preferably 600 to 1500, more preferably 700 to 1300. The polypropylene glycol is preferably poly-1,2-propylene glycol.

[0145] Supplementary ingredients The cleaning composition may optionally contain builders (preferably citrates), as well as many other adjunct ingredients such as chelating agents, conditioning polymers, other cleaning polymers, surface modifying polymers, structurants, emollients, humectants, skin rejuvenation actives, enzymes, carboxylic acids, scrubbing particles, fragrances, malodor control agents, pigments, dyes, opacifiers, pearlescent particles, inorganic cations such as alkaline earth metals such as Ca / Mg ions, antimicrobial agents, preservatives, antioxidants, viscosity modifiers (e.g., salts such as NaCl and other mono-, di-, and trivalent salts), and pH adjusters and buffering means (e.g., carboxylic acids such as citric acid, HCl, NaOH, KOH, alkanolamines, carbonates such as sodium carbonate, bicarbonates, sesquicarbonates, and the like).

[0146] When present, the compositions will contain from 0.01% to 2.0%, preferably from 0.05% to 1.5%, or more preferably from 0.1% to 1.0% by weight of alkaline earth metal ions, with magnesium and / or calcium ions being especially preferred. Lower concentrations of transition metal ions may also be present in liquid detergent compositions, such as up to 1.0%, or up to 0.5% by weight of the composition.

[0147] Packaged product The hand dishwashing detergent composition can be packaged in a container, typically a plastic container. A suitable container includes an orifice. Typically, the container includes a cap, and the orifice is typically provided on the cap. The cap can include an inlet, and the orifice is at the outlet of the inlet. The inlet can have a length of 0.5 mm to 10 mm.

[0148] The orifice is 3mm at the outlet. 2 ~20mm 2 , preferably 3.8 mm 2 ~12mm 2 , more preferably 5 mm 2 ~10mm 2 and the container further comprises a composition according to the present invention, the cross-sectional area being measured perpendicular to the liquid outlet from the container (i.e. perpendicular to the liquid flow during dispensing).

[0149] The container can typically contain 200 ml to 5,000 ml, preferably 350 ml to 2000 ml, more preferably 400 ml to 1,000 ml of the liquid hand dishwashing detergent composition.

[0150] Alternatively, the hand dishwashing detergent composition can be packaged in an inverted container. Such an inverted container typically comprises a cap at the bottom of the container, the cap comprising either a lid or a self-sealing valve, or a combination thereof. The cap preferably comprises a self-sealing valve. Suitable self-sealing valves include slit valves. The self-sealing valve defines an orifice that recoils open when pressure applied to the inside of the valve exceeds pressure applied to the outside of the valve. The bottom-shaped pouring container can comprise an impact-resistant system, such as that described in WO2019108293A1.

[0151] Cleaning Method The resulting liquid detergent composition can be used for manual washing. A suitable method includes providing such a liquid detergent composition to a volume of water to form a washing solution, and immersing the dishware in the washing solution. The dishware is washed with the composition in the presence of water. The dishware may be rinsed. As used herein, "rinsing" refers to contacting the dishware washed in the process according to the invention with a substantial amount of a suitable solvent, typically water. "Substantial amount" typically means about 1 to about 20 L or under running water.

[0152] The compositions herein may be applied in their diluted form. The soiled dishes are contacted with an effective amount, typically about 0.5 mL to about 20 mL, preferably about 3 mL to about 10 mL (per about 25 dishes to be treated), of the detergent composition of the present invention diluted with water, preferably in liquid form. The actual amount of cleaning composition used is at the discretion of the user and typically depends on factors such as the particular product formulation of the cleaning composition, including the concentration of active ingredients in the cleaning composition, the number of soiled dishes to be cleaned, and the degree of soiling of the dishes. Generally, about 0.01 mL to about 150 mL, preferably about 3 mL to about 40 mL, of the cleaning composition of the present invention is combined with about 2,000 mL to about 20,000 mL, more typically about 5,000 mL to about 15,000 mL of water in a sink. After immersing the soiled dishes in the sink containing the diluted cleaning composition thus obtained, the soiled surface of the dishes is contacted with a cloth, sponge, or similar cleaning implement. The cloth, sponge, or similar cleaning implement may be immersed in the mixture of cleaning composition and water prior to contacting with the dishware, typically for a period of time ranging from about 1 to about 10 seconds, although the actual period of time will vary with each application and user. Contacting the cloth, sponge, or similar cleaning implement with the dishware involves simultaneously scrubbing the dishware.

[0153] Preferably, the composition is applied in its undiluted form to the tableware to be treated. "In its undiluted form" means herein that the composition is applied directly to the surface to be treated or to a cleaning device or implement, such as a brush, sponge, nonwoven or woven material, without any significant dilution by the user prior to (immediately prior to) application. Application using a sponge is preferred. "In its undiluted form" also includes slight dilution, for example due to the presence of water on the surface of the cleaning device, or the addition of water by the consumer to remove residual amounts of the composition from a bottle. Thus, the composition in undiluted form includes a mixture having the composition and water in a ratio ranging from 50:50 to 100:0, preferably 70:30 to 100:0, more preferably 80:20 to 100:0, even more preferably 90:10 to 100:0, depending on the user's habits and cleaning tasks.

[0154] Test Method A) pH: pH is measured as a 10% aqueous solution in demineralized water at 20° C. using a pH meter such as an Orion Model 720A equipped with an Ag / AgCl electrode (e.g. Orion sure flow electrode model 9172BN) and calibrated using standardized pH 7 and pH 10 buffer solutions.

[0155] B) Reserve Alkalinity: Reserve Alkalinity is defined as the grams (NaOH) / 100 g (composition) required to titrate a test composition at pH 7.0 to the pH of the test composition. The reserve alkalinity of a solution is measured as follows:

[0156] Reserve alkalinity is measured on a 10% solution of concentrated surfactant blend in deionized water at 20° C. Thus, 50 g of concentrated surfactant blend is diluted to 10% with deionized water and mixed for 5 minutes until completely homogenized. 100 g of the 10% solution is then titrated using an automated titrator such as the Omnis sample robot and Omnis titrator supplied by Metrohm with 0.1 N hydrochloric acid (HCl) and a pH meter (as described above) until an endpoint of pH 4 is achieved or the maximum titration volume of the titrator is reached (25 ml for the titrator described above). The volume of titrant required to reach pH 7.0 is recorded or, if the maximum titration volume is reached, the final pH and volume of titrant are recorded.

[0157] Reserve alkalinity is calculated as follows: Reserve alkalinity = ml 0.1N HCl needed to reach a pH of 7.0 x 0.1 (equivalents / liter) x equivalents NaOH (g / equivalent) x 10.

[0158] When the maximum titer from the titrator is reached, record the final pH and calculate the reserve alkalinity for this pH. The reserve alkalinity up to pH 7.0 can then be estimated by linear extrapolation to pH 7.0 of the "pH vs. volume of titrant" titration curve obtained between 20 ml and 25 ml of added titrant volume.

[0159] C) Concentrated Surfactant Blend Viscosity: The rheological profile is measured using a "TA instruments DHR1" rheometer (TA instruments, serial number: SN999393) using a cone and plate configuration (flat steel Peltier plate and 2.008° cone with a diameter of 40 mm). The viscosity measurement procedure includes a conditioning step at 20°C and a sweep step. The conditioning step is 10 seconds at zero shear at 20°C, followed by a 10 second sweep. -1 This consisted of pre-shearing at 400° C. for 10 seconds followed by equilibrating the sample at zero shear for 30 seconds.

[0160] The upward shear rate sweep was performed for 0.1 s -1 ~100s -1 The shear rate was measured in increments of 10 points, with each increment being performed automatically by the rheometer after the measurement had stabilized. Unless otherwise stated, the viscosity was measured at 10 s -1 The measurements are performed at a shear rate of 100 Hz and at a temperature of 20°C.

[0161] D) Flow index and yield stress of concentrated surfactant blends: Similar to the viscosity measurements of concentrated surfactant blends, the rheological profile is measured using a "TA instruments DHR1" rheometer (TA instruments, serial number: SN999393) using a cone and plate configuration (flat steel Peltier plate and 2.008° cone with a diameter of 40 mm). The viscosity measurement procedure includes a conditioning step at 20°C and a sweep step. The conditioning step is 10 seconds at zero shear at 20°C, followed by a 10 second sweep. -1 This consisted of pre-shearing at 400° C. for 10 seconds followed by equilibrating the sample at zero shear for 30 seconds.

[0162] The upward shear rate sweep was performed for 0.1 s -1 ~100s -1From a shear rate of 100, 10 point increments are performed, with each incremental step being automatically performed by the rheometer after the measurement has stabilized.

[0163] The shear stress is recorded by the rheometer as a function of shear rate. Then, according to the Herschley Buckley model: τ = τ0 + Kγ n where "τ" is the shear stress, "τ0" is the yield stress, and γ is the shear rate. "K" is the consistency index, and "n" is the flow index.

[0164] E) Viscosity change with temperature of concentrated surfactant blends: Rheological variations with temperature were measured using a TA instruments DHR1 rheometer (TA instruments, serial number: SN999393) using a cone and plate configuration (flat steel Peltier plate and a 2.026° cone with a diameter of 40 mm) for 10 s. -1 A temperature sweep from 60 °C to 5 °C using a shear rate of 10 s at 60 °C and a temperature gradient of 2 °C / min. -1 The measurement is performed after an equilibration step of 100 seconds at a shear rate of 100 s.

[0165] F) Viscosity measurement of detergent compositions: The viscosity of the detergent compositions is measured at 20° C. using a Brookfield RT viscometer using spindle 31 with the RPM of the viscometer adjusted to achieve a torque of 40% to 60%.

[0166] G) Foaming properties of detergent compositions: The initial foaming of the composition is evaluated using a KRUSS DFA100 dynamic foam analyzer. The detergent composition is diluted to 50% with water having a hardness of 2.67 mmol / l equivalent of CaCO3 at 22°C. 50 ml of the diluted solution is injected using a syringe into a standard glass column (CY4501) mounted on a Quick Fit Unit (SH4512) for stirring, equipped with a standard impeller (SR4501). The initial solution height is recorded.

[0167] The solution is then stirred at 5000 RPM for 5 seconds. 20 seconds after stirring has stopped, the total height of the sample (foam + liquid solution) is recorded. To calculate the foam height, subtract the initial solution height from the total height measured.

[0168] H) Foam Durability Index: The purpose of the foam persistence test is to compare the change in foam volume produced over time for different test agents at specified water hardness, solution temperature and formulation concentration while under the influence of intermittent soil injection. The data is compared and expressed as a foam persistence index relative to a reference composition (the reference composition has a foam persistence index of 100). The steps of the method are as follows: 1. Using a plastic pipette at a flow rate of 0.67 mL / sec into a stream of water with water hardness of 0.36 mmol / L (2.0 gpg) of calcium carbonate, 1.25 mmol / L (7.0 gpg) of calcium carbonate, and 2.67 mmol / L (15 gpg) of calcium carbonate, and a water temperature of 35° C., 0.12 wt. % of the test composition is dispensed at a height of 37 cm above the bottom of a sink (dimensions: diameter 300 mm, height 288 mm) and the sink is filled to 4 L at a constant pressure of 4 bar. 2. Initial foam volume generated (measured as the average foam volume X above the liquid in the sink (cm 3 (expressed as ) is recorded immediately after filling is completed. 3. Immediately pour a fixed volume (6 mL) of the stain containing the specified composition below into the center of the sink. The resulting solution is mixed using a metal blade (10 cm x 5 cm) positioned at a 45° angle to the air-liquid interface in the center of the sink, rotating 20 times at 4.85 RPM. 5. Another measurement of the total lather volume is recorded immediately after the blade rotation has finished. 6. The measured total foam volume is 400 cm 3 Repeat steps 3-5 until you reach a level of 400cm 3 The amount of soil added required to reach a level of foam persistence is considered the foam persistence of the test composition. 7. Each test composition is tested four times per test condition (i.e., water temperature, composition concentration, water hardness, soil type). 8. Calculate the average foam persistence as the average of four replicates per sample for the stated test conditions. 9. Compare the average persistence of the test composition samples to the reference composition samples and calculate the Lather Persistence Index. The calculation is as follows:

[0169]

number

[0170] The greasy soil compositions used for testing are prepared by standard mixing of the ingredients set out in Table A.

[0171] [Table 1] EXAMPLES

[0172] The effect of alkyl sulfate neutralization in the presence (invention) and absence (comparison) of amine oxide buffer surfactant on the rheology of the resulting concentrated surfactant blend, as well as the dilution, foaming, and physical stability of the final product, was studied according to the test methods described herein. The buffered concentrated surfactant blend was made at pilot plant scale by sulfated and neutralized the material in a falling film reactor using SO3 gas as described herein.

[0173] In the inventive examples, the neutralization stream was an aqueous solution of sodium hydroxide and C12-C14 dimethylamine oxide (as a buffer surfactant) at the concentrations shown in Table 1. In the comparative examples, the neutralization stream was an aqueous solution of sodium hydroxide with no added buffer surfactant.

[0174] The blend of Example 1 (invention) contained a branched alkyl sulfate having a weight average degree of branching of 50% and an amine oxide buffer surfactant in a ratio of 4.4:1. The blend of Comparative Example A was similar to Example 1, but contained a weight average degree of branching of 55% (higher than required by the invention). The blend of Comparative Example B was similar to Example 1, except that a linear alkyl sulfate was used.

[0175] Comparative Blends D-E used the same alkyl sulfates as Inventive Example 1 and Comparative Examples A and B, respectively, but did not include a buffering surfactant. Thus, a higher concentration of sodium hydroxide was required to ensure a high enough pH to achieve a robust reserve alkalinity (to avoid rehydrolysis of the alkyl sulfates).

[0176] [Table 2] * comparison 1 50% branched C12-C13 alkyl sulfate produced from Safol™ 23 alcohol, a Fischer-Tropsch derived alcohol supplied by Sasol 2 55% branched C12-C13 alkyl sulfate produced from Lial™ 123 alcohol, an OXO alcohol supplied by Sasol 3 Linear C12-C14 Alkyl Sulfates Produced by P&G Chemicals from Naturally Occurring Alkyl Chains Distilled from Palm Kernel Oil 4 C12-C14 Dimethylamine Oxide produced by P&G Chemicals

[0177] As can be seen from the results in Table 1a above, the compositions of the present invention containing buffered surfactants had higher reserve alkalinity and therefore stronger robustness to rehydrolysis of alkyl sulfates, despite using less alkali (sodium hydroxide). In addition, the lower amount of alkali resulted in less salt being present in the concentrated surfactant blend, resulting in a more stable and pourable viscosity.

[0178] Furthermore, as can be seen from the viscosity data, the concentrated surfactant blends of the present invention, which include a buffered surfactant, have a more easily processable viscosity profile, as opposed to the comparative compositions which do not include a buffered surfactant. Small differences in surfactant concentration between the inventive and comparative examples do not result in appreciable differences in the measured viscosity.

[0179] In fact, the concentrated surfactant blends of Comparative Compositions C and D had a viscosity that was almost a solid gel, and the viscosity was not measurable. When water was added to these compositions to reach the same activity levels as inventive composition 1 and comparative compositions A and B, composition C entered a gel phase, and composition D remained in a highly viscous gel phase, and the viscosity of both was not measurable.

[0180] Example 2 is a further example of the invention, and Examples FH are further comparative examples (having degrees of branching outside the scope of the invention) using different ratios of anionic surfactant to buffer surfactant.

[0181] [Table 3] 5 Extrapolated value (reach the titration limit)

[0182] The surfactant blend of Comparative Example B (see Table 1 above) was recreated (Comparative Example H) and formulated into a detergent composition (Comparative Detergent Example B). Comparative Detergent Example A was formulated using a commercially available concentrated alkyl sulfate blend (Tensopol® S30LSHPH, available from KLK Oleo) that does not contain a buffering surfactant. Tensopol® S30LSHPH is a liquid form of 30% active sodium lauryl sulfate with a high pH (above pH 11.0). The pH of Detergent Composition B was adjusted (using sodium hydroxide) to reach a pH of 9.2. The pH of Comparative Detergent Composition A was adjusted (using citric acid) to reach the same pH of 9.2. The resulting compositions are shown in Table 3 below. The concentration of amine oxide shown for Detergent Composition B includes the portion added with the concentrated surfactant blend of Comparative Example H and the portion added later when making the composition. It is not known how much alkali was in the Tensopol® S30LSHPH starting material for Detergent Composition A, so this is marked as "unknown."

[0183] [Table 4]

[0184] To evaluate the dispersibility of the detergent compositions, detergent composition B (made using the process of the present invention but with comparative surfactant blend H made with alcohols having linear alkyl chains) and detergent composition A (which is comparative and made using a different process) were diluted with demineralized water to the concentrations shown in Table 3 below and the viscosity was measured using the Brookfield Viscosity Test Method described herein. The lower the viscosity upon dilution, the more easily the composition will disperse when added to a sink full of water.

[0185] [Table 5]

[0186] As can be seen from the data above, compositions produced from concentrated surfactant blends made using the process of the present invention are more easily dispersed, even though they contain the same concentration of active ingredients and have essentially the same starting viscosity. Although Comparative Detergent Composition B above was made using a comparative surfactant blend having a degree of branching greater than that required for the present invention (55%), the improvement in viscosity upon dilution can be interpolated for surfactant blends made by the present process using alkyl alcohols having the degree of branching required for the present invention.

[0187] In addition, the foaming properties of Comparative Detergent Composition B and Comparative Detergent Composition A were evaluated. The foaming properties of the two compositions were measured according to the Foaming Test Method described herein. The amount of foam generated is summarized in Table 4.

[0188] [Table 6]

[0189] As can be seen from the data above, compositions produced from concentrated surfactant blends made using the present process, albites containing anionic surfactants with a degree of branching greater than that required by the present invention, foam more readily even though they contain the same concentration of active ingredient. Again, although Comparative Detergent Composition B above was made using a comparative surfactant blend with a degree of branching greater than that required by the present invention (55%), the foaming improvement can be extrapolated to surfactant blends made by the present process using alkyl alcohols with the degree of branching required by the present invention.

[0190] The surfactant blend of Comparative Example H (made by this process but using an alkyl alcohol having a weight average degree of branching of 55%, see Table 3 above) was formulated to form Comparative Detergent Composition C. Comparative Detergent Example D was formulated using the same commercially available concentrated alkyl sulfate blend (Tensopol® S30LSHPH available from KLK Oleo) used to make Comparative Detergent Composition A. In both cases, the pH was adjusted to pH 9.2. The resulting detergent compositions are shown below in Table 6.

[0191] [Table 7] ** Averaged across water hardness levels of 2, 7, and 15 gpg

[0192] As can be seen from the above data, the composition produced by the process of the present invention but using an alkyl alcohol having a weight average degree of branching of 55% (Detergent Composition C) foams more readily than comparable detergent compositions made using surfactant blends formed from conventional processes, has improved freeze-thaw recovery, and does not adversely affect foam persistence in the presence of greasy soils, even though they contain the same concentration of active ingredients. Although Comparative Detergent Composition C above was made using a comparative surfactant blend having a degree of branching greater than that required for the present invention (55%), the improvement in low temperature stability can be interpolated for surfactant blends made by the present process using alkyl alcohols having the degree of branching required for the present invention.

[0193] The effect of branching of the alkyl alcohol in the present process is illustrated by the following comparative test. Three alcohol blends were used: Alcohol Blend 1 had a branching degree of 42.1%. Alcohol Blend A had a higher branching degree of 62.5% (again mainly C2 branching), while Alcohol Blend B had a higher branching degree of 86.6%. Alcohol Blends 1 (used in the present invention) and A and B were mainly branched at the C2 position.

[0194] All blends contained the same C13 branched (non-ethoxylated) alcohol, C13 branched ethoxylated (up to 3.0 degrees) alcohol, and C12-14 linear (non-ethoxylated) alcohol, mixed in different ratios to achieve an average degree of ethoxylation of 0.6 and the desired degree of branching.

[0195] The sulfation process was carried out at pilot plant scale by sulfating the material in a falling film reactor using SO3 gas.

[0196] C12-C14 dimethylamine oxide was added as a buffering surfactant during the neutralization step to provide a weight ratio of alkyl sulfate to buffering surfactant of 4.4:1.

[0197] The sulfation reaction completion rate was determined for each alcohol blend.

[0198] [Table 8] + is the weight of the starting C13 alcohol, the remainder is linear alcohol

[0199] As can be seen from the above data, in the process of the present invention, limiting the branching degree of the starting alcohol required in the present invention leads to an improvement in the reaction completion rate. As a result, in addition to improved reaction yield, there is less unreacted alcohol. Improved reaction yield leads to a more cost-effective process. The reduction in unreacted alcohol provides the additional benefit of improved low temperature stability of both concentrated surfactant blends and detergent compositions made with such blends. This is because unreacted alcohol is more hydrophobic than sulfated surfactants and acts as a seed for precipitation of other ingredients, thus resulting in reduced phase stability, especially at low temperatures.

[0200] It is known in the art that higher concentrations of SO3 are required to increase the completeness of the reaction.Thus, operating at high completeness is economically beneficial and results in a reduction in the concentration of unreacted alkyl alcohol, but in conventional processes, the molar ratio of SO3 to alcohol must be increased beyond the stoichiometric ratio, which usually results in a higher sulfuric acid concentration in the acid blend after sulfation.In conventional processes, this typically meant that more alkali was required in the neutralization step, resulting in a higher salt concentration in the resulting concentrated surfactant blend.

[0201] In contrast, in the process of the present invention, which adds buffer surfactant before or during the neutralization step, this additional salt is at least reduced.As a result, the process of the present invention leads to higher reaction yields, less unreacted alkyl alcohol, and less salt.Both the reduction in unreacted alkyl alcohol and the reduction in salt concentration lead to improved stability, especially at low temperatures, of the resulting concentrated surfactant blend and the detergent composition made with them.

[0202] Dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​recited. Instead, unless otherwise indicated, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

Claims

1. 1. A process for making a concentrated surfactant blend, the concentrated surfactant blend comprising an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, the process comprising: a. providing an alkyl alcohol stream comprising at least one alkyl alcohol, wherein the alkyl alcohol in the alkyl alcohol stream has a weight average degree of branching of from 15% to 50%; b. a sulfation step in which the at least one alkyl alcohol in the alkyl alcohol stream is sulfated to form an alkyl sulfate stream comprising at least one alkyl sulfate; c. providing a neutralization stream comprising at least one neutralizing agent; d. a neutralization step of combining said alkyl sulfate stream with said neutralization stream to neutralize said alkyl sulfate; the buffering surfactant is added before or during the neutralization step; the buffer surfactant is added at a concentration that provides the resulting concentrated surfactant blend with a reserve alkalinity of greater than 0.02, when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20° C.; wherein the resulting concentrated surfactant blend has a pH of from 7.1 to 10 when measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20°C.

2. 10. The process of claim 1, wherein the alkyl alcohol in the alkyl alcohol stream comprises a blend of alkyl alcohols.

3. 3. The process of claim 1 or 2, wherein the alkyl alcohol in the alkyl alcohol stream has a molar average alkyl chain length of from 8 to 18, preferably from 10 to 14, and most preferably from 12 to 13 carbon atoms.

4. 4. The process of any one of claims 1 to 3, wherein the alkyl alcohol in the alkyl alcohol stream has a weight average degree of branching of from 20% to 40%.

5. 5. The process of any one of claims 1 to 4, wherein the alkyl alcohol in the alkyl alcohol stream prior to the sulfation step has an average degree of alkoxylation of less than 0.5, preferably less than 0.1, and more preferably is not alkoxylated.

6. the alkyl alcohol comprises a branched alkyl alcohol; a. the branched alkyl alcohol comprises a C2 branched alkyl alcohol and a non-C2 branched alkyl alcohol, wherein the weight ratio of the non-C2 branched alkyl alcohol to the C2 branched alkyl alcohol is greater than 0.5, preferably from 1.0:1 to 5:1, more preferably from 2:1 to 4:1; b. The process of claim 5, wherein the non-C2 branched alkyl alcohol comprises less than 30% by weight of the non-C2 branched alkyl alcohol, preferably less than 20% by weight, more preferably less than 10% by weight of the non-C2 branched alkyl alcohol, and most preferably the non-C2 branched alkyl alcohol does not comprise any C1 branched alkyl alcohol.

7. 5. The process of any one of claims 1 to 4, wherein the at least one alkyl alcohol in the alkyl alcohol stream is alkoxylated to an average degree of alkoxylation of less than 3.5, preferably from 0.3 to 2.0, more preferably from 0.5 to 0.

9.

8. A process according to any one of claims 1 to 7, wherein the sulfation step is carried out in a liquid-gas interface reactor, preferably a falling film reactor.

9. The process of any one of claims 1 to 8, wherein the buffering surfactant is added during the neutralization step.

10. 10. The process according to any one of claims 1 to 9, wherein the buffering surfactant is selected from the group consisting of amine oxide surfactants, betaine surfactants, and mixtures thereof, preferably amine oxide surfactants, more preferably C12-C14 alkyl dimethyl amine oxide, C12-14 alkyl amido propyl amine oxide, and mixtures thereof.

11. 11. The process of any one of claims 1 to 10, wherein the alkyl sulfate and the buffer surfactant are combined in a weight ratio of the alkyl sulfate to the buffer surfactant of from 10:1 to 1:1, preferably from 8:1 to 2:1, more preferably from 6:1 to 3:

1.

12. 12. A process according to any one of the preceding claims, wherein during or after the neutralisation step, the neutralising agent is added in a concentration to provide the resulting concentrated surfactant blend having a pH of from 7.3 to 9.5, more preferably from 7.5 to 9.0, measured as a 10% by weight solution of the concentrated surfactant blend in demineralised water at 20°C.

13. 13. The process of any one of claims 1 to 12, wherein the buffer surfactant is added at a concentration to provide the resulting concentrated surfactant blend with a reserve alkalinity of from 0.04 to 0.50, more preferably from 0.06 to 0.30, measured as a 10% by weight solution of the concentrated surfactant blend in demineralized water at 20°C.

14. 1. A concentrated surfactant blend comprising: a. from 30% to 70% by weight of the concentrated surfactant blend of an alkyl sulfated anionic surfactant, said alkyl sulfated anionic surfactant having an average degree of alkoxylation of less than 0.5, and a weight average degree of branching of from 15% to 50%; b. 1.0% to 25% by weight of said concentrated surfactant blend of a buffering surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof. Including, 1. A concentrated surfactant blend, wherein said buffering surfactant is present in a concentration that provides said resulting concentrated surfactant blend with a reserve alkalinity of greater than 0.02, when measured as a 10% by weight solution of said concentrated surfactant blend in demineralized water at 20° C., and said resulting concentrated surfactant blend has a pH of from 7.1 to 10, measured as a 10% by weight solution of said concentrated surfactant blend in demineralized water at 20° C.

15. The blend is a. 40% to 60%, preferably 45% to 55%, by weight of said concentrated surfactant blend of said alkyl sulfated anionic surfactant; b. 5.0% to 20%, preferably 10% to 15%, by weight of said concentrated surfactant blend of said buffer surfactant.

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