Process for creating concentrated surfactant blends

Abstract

The present invention provides a concentrated surfactant blend containing an alkyl sulfated anionic surfactant that does not require a high pH for hydrolysis stability, and therefore does not contain high concentrations of salts, nor does it require the addition of high concentrations of organic solvents or structuring agents for stability, and can be used to form detergent compositions having a desired viscosity, solubility, and foaming profile. [Solution] A process for producing a concentrated surfactant blend, wherein the blend comprises an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, wherein the process involves adding the buffered surfactant before 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 producing concentrated surfactant blends, particularly for use in producing liquid detergent compositions, and especially liquid hand-washing dishwashing detergent compositions. [Background technology]

[0002] Liquid hand-washing dishwashing detergent compositions typically provide high foaming and long-lasting foam in addition to good grease removal, in order 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. Examples of alkyl sulfated anionic surfactants include non-alkoxylated alkyl sulfate surfactants and alkoxylated alkyl sulfate surfactants, such as ethoxylated alkyl sulfate surfactants.

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

[0004] In order to suggest to the user the "richness" of the ingredients, liquid dishwashing detergent compositions should also have high viscosity.

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

[0006] Various reagents have been used in the sulfation process, but 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 cyclic flow-down membrane reactors, or multi-tube membrane reactors, such as "Ballestra" reactors. In such processes, SO3 is typically first diluted with air. Such air / SO3 sulfation processes are direct processes in which gaseous SO3 is diluted with very dry air and reacted directly with the alkyl alcohol feedstock. The reaction between gaseous SO3 and 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 is typically incomplete. Therefore, some acidic residue remains and needs to be neutralized to achieve the desired pH of the blend. Thus, the resulting blend contains neutralized salts and unreacted alkyl alcohols. Both result in reduced phase stability, especially at low temperatures.

[0007] Alternatively, sulfamic acid may be used in the sulfation step to form ammonium salts. Sulfamic acid is a mild and specific sulfating reagent suitable for producing ammonium-neutralized alcohol ethoxylates. An advantage of sulfamic acid is that it selectively sulfates alcohol groups and does not sulfonate aromatic rings. Therefore, it is particularly suitable for the sulfation of alkylphenol ethoxylates to prevent the formation of mixed sulfate-sulfonate compounds. An 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 sulfamic acid is used, only ammonium-neutralized salts of alkyl sulfate surfactants can be prepared. The pH of a composition comprising such ammonium salts of alkyl sulfate surfactants needs to be less than 8 to avoid ammonia odor from the detergent composition, which limits the use of surfactants prepared using this sulfating reagent. Alternatively, an ion exchange process may be used to replace 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, in such processes, the surfactant concentration in the resulting blend is typically as low as less than 30%, which limits their use in low-activity detergent compositions and increases the transportation cost of the blend.

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

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

[0010] Typically, alkyl sulfate-containing surfactant blends are used to produce detergent compositions with a pH of 7.0–9.0. Therefore, 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 causes challenges in both viscosity and phase stability, especially at low temperatures. Therefore, more organic solvents or structuring agents need to be added to provide the desired low-temperature stability and viscosity profile. High salt and solvent concentrations also complicate the formulation of the final liquid detergent composition, as they can affect the solubility of other active substances. High salt concentrations also make the detergent composition less soluble, leading to greater user dissatisfaction.

[0011] Before 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 cleaning and foaming performance. When producing alkoxylated, especially ethoxylated alkyl sulfate surfactants, 1,4-dioxane may be generated. Typically, strict control of processing conditions and raw material compositions is required in both the alkoxylation, particularly ethoxylation, and sulfation steps, so as to minimize the amount of 1,4-dioxane by-product in the alkoxylated, particularly ethoxylated alkyl sulfate. Even when the concentration of 1,4-dioxane by-product is kept at a minimum in a newly formed surfactant blend, for many blends formed by prior art processes, the concentration of 1,4-dioxane by-product increases over time. It has been found that the formation of 1,4-dioxane is higher when concentrated alkyl ethoxylated sulfate blends are stored at higher pH.

[0012] Accordingly, there remains a need for a process for forming an alkyl sulfated anionic surfactant-containing concentrated surfactant blend that does not require a high pH to be stable to hydrolysis, and thus can be used to form a detergent composition that is stable and does not contain high concentrations of salt or require addition of high concentrations of organic solvents or structuring agents to achieve a desired viscosity profile. Furthermore, there is a need for a process for producing concentrated surfactant blends that are more stable, particularly at low temperatures. In addition, there remains a need for a process for forming an alkyl alkoxylated sulfate-containing concentrated surfactant blend that has a low concentration of 1,4-dioxane by-product, and the 1,4-dioxane by-product does not substantially increase over time.

[0013] U.S. Patents 4,477372(A), 4,476044(A), and 4476045(A) relate to highly active surfactants containing a high concentration of active substances, wherein the anionic portion of the surfactant comprises at least three carbon atoms bonded to the nitrogen atom of the amine, with at least one alcoholic hydroxyl group, and the amine is neutralized with a secondary or tertiary amine such that the amine is alpha- or beta-substituted with respect to the nitrogen atom product. International Publication 9418160(A) relates to a process for producing a highly active alkyl sulfate solution, comprising the step of adding and mixing an alkyl sulfate having a chain length of C12-C18 with an organic amine to produce a substantially water-free neutralization product. European Patent 2,964741(A) relates to a method for preparing a substantially anhydrous composition of alkyl (ethoxy) sulfate neutralized with an organic amine base, the composition being suitable for use as a surfactant in ecodose. International Publication No. 201472840(A) relates to a process for preparing a high-concentration, fluid aqueous fatty alkyl sulfate solution, the process comprising: (i) ethoxylation of a fatty alcohol with a very low amount of about 0.3 to about 0.8 moles of ethylene oxide; (ii) sulfation of the ethoxylated fatty alcohol under specific reaction conditions; and (iii) neutralization of the sulfation product with an aqueous base, wherein the resulting fatty alkyl sulfate solution comprises a mixture of fatty alkyl sulfate and fatty alkyl ether sulfate in a weight ratio of about 80:20 to about 50:50, with an average mole count of ethylene oxide (EO) of 0.3 to 0.8, a mixture, less than 3 ppm of dioxane, and water, the solution is free of any antimicrobial or preservative agents, is homogeneous at 25°C, is fluid, and can be pumped. International Publication No. 9738972(A) relates to a sulfation method for producing longer-chain alkyl sulfate and / or alkylalkoxylated sulfate surfactant compositions, the method utilizing the presence of a large amount of medium-chain branched alcohol and / or polyoxyalkylene alcohol in the sulfation reaction to significantly lower the reaction temperature, thereby improving the quality of the product and saving energy.International Publication No. 9404640(A) relates to a concentrated aqueous surfactant solution containing an alkyl ether sulfate and an alkaline earth metal, preferably magnesium, wherein the composition is a stable liquid suitable for use in cleaning products, particularly dishwashing solutions, and the concentrated surfactant solution can be prepared by partially neutralizing an acid precursor with an alkaline earth metal hydroxide or oxide, followed by further neutralization with an alkali metal or ammonium hydroxide. International Publication No. 9105764(A) relates to the sulfation of ethoxylated alkanols obtained by the reaction of ethylene oxide with an alcohol containing 8 to 22 carbon atoms in the presence of a hydrotalcite catalyst, providing an alkyl polyethoxy ether sulfate characterized by a low dioxane content and excellent coagulation properties using conventional electrolytes. U.S. Patent Application Publication No. 20170158625(A) relates to a process for preparing an alcohol ether sulfate, comprising (a) sulfating an alkoxylated alcohol and (b) neutralizing the sulfation product of step (a) in the presence of a base and a cosolvent having a flash point of at least 60°C. British Patent No. 977281(A) relates to a surface-active sulfate of alkyl ether alcohols, wherein the ether alcohol may be prepared by (a) a reaction of an olefin with ethylene glycol, (b) a reaction of an olefin with ethylene halohydrin followed by hydrolysis of the halogen-containing product, or (c) a reaction of a secondary or tertiary alcohol with ethylene oxide, all of which are sulfated with chlorosulfonic acid. European Patent No. 3919594(A1) relates to a liquid detergent composition suitable for washing dishes, which is suitable for both in-sink and direct application methods, and which has good foam persistence and good viscosity, particularly under in-sink application methods, while providing reduced smearing when used in a direct application dishwashing method, wherein the liquid detergent composition comprises an alkyl sulfate anionic surfactant, which includes a C13 alkyl sulfate anionic surfactant, and the C13 alkyl sulfate anionic surfactant comprises a specific fraction of a 2-branched C13 alkyl sulfate anionic surfactant, along with a specific distribution of 2-branching. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] U.S. Patent No. 4,477,372(A) [Patent Document 2] U.S. Patent No. 4476044(A) [Patent Document 3] U.S. Patent No. 4476045(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) [Overview of the project] [Means for solving the problem]

[0015] The present invention relates to a process for producing a concentrated surfactant blend, wherein the concentrated surfactant blend comprises an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, and the process comprises a step of providing an alkyl alcohol stream containing at least one alkyl alcohol, a sulfation step of sulfating at least one alkyl alcohol in the alkyl alcohol stream to form an alkyl sulfuric acid stream containing at least one alkyl sulfuric acid, a step of providing a neutralization stream containing at least one neutralizing agent, and a neutralization step of combining the alkyl sulfuric acid stream and the neutralization stream to neutralize the alkyl sulfuric acid, wherein the buffered surfactant is added before or during the neutralization step, and the buffered surfactant is added at a concentration that provides a concentrated surfactant blend having a pre-alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C, and the 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 desalted water at 20°C.

[0016] The present invention further relates to a concentrated surfactant blend comprising 30% to 70% by weight of an alkyl sulfated anionic surfactant, wherein the alkyl sulfated anionic surfactant has an average degree of alkoxylation of less than 0.5, and 1.0% to 25% by weight of a buffering surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, wherein the concentrated surfactant blend has a preliminary alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C using the method 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 desalted water at 20°C. [Modes for carrying out the invention]

[0017] It has been found that adding a buffering surfactant before or during the neutralization process results in a more hydrolyzable concentrated surfactant blend, and therefore, the concentrated surfactant blend can be kept at a lower pH. Furthermore, when such a concentrated surfactant blend is incorporated into a detergent composition, less acid needs to be added to reach the desired pH. Consequently, the resulting liquid detergent composition 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 to no organic solvents and / or added structuring agents. It has also been found that a lower salt content in the final product composition promotes the dissolution of the final product, resulting in a faster onset of foam formation during washing. Furthermore, since the concentrated surfactant blend can be maintained at a lower pH, the formation of 1,4-dioxane is reduced or eliminated both during preparation and storage.

[0018] While salt-based buffering systems can limit the pH tendency of concentrated surfactant blends, they introduce additional salts into the final detergent composition, which negatively impacts both low-temperature stability and viscosity. In contrast, the buffered surfactants used herein offer the advantages of washing and foaming in addition to buffering, without negatively affecting the viscosity and physical product stability of the composition.

[0019] When used herein, articles such as "a" and "an" used in the claims are understood to mean one or more of the claims or descriptions.

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

[0021] As used herein, the term “dishware” includes, in a non-limiting sense, cookware and tableware made from ceramics, porcelain, metal, glass, plastics (e.g., polyethylene, polypropylene, polystyrene, etc.) and wood.

[0022] As used herein, the terms “oils and fats” or “oil-based” mean that the substance contains, at least partially (i.e., at least 0.5% by weight of oils and fats in the substance), saturated and unsaturated fats and oils, preferably oils and fats derived from animal raw materials such as beef, pork, and / or chicken.

[0023] The term "include / includes / including" means that something is not restrictive.

[0024] As used herein, the term “particulate matter” means inorganic and, in particular, organic solid contaminant particles, in particular food particles, and, in non-limiting examples, ultrafine elemental carbon particles, calcined fat particles, and meat particles.

[0025] As used herein, the term “foaming profile” refers to the properties of a cleaning composition relating to the nature of the foam during the dishwashing process. The “foaming profile” of a cleaning composition includes the dissolution and agitation of the cleaning composition in an aqueous cleaning solution, the initial foam volume typically generated during manual agitation, and the retention of foam during the dishwashing process. Preferably, a hand-washing dishwashing cleaning composition characterized by having a “good foaming profile” tends to have a large initial foam volume and / or persistent foam volume, particularly over a significant portion or the entirety of the hand-washing process. This is important because consumers use high foaming as an indicator that a sufficient amount of cleaning composition has been added. Furthermore, consumers also use the persistence of foam volume, even towards the end of the dishwashing process, as an indicator that sufficient active cleaning components (e.g., surfactants) are present. Consumers typically refresh the cleaning solution when foaming decreases. Therefore, low-foaming cleaning compositions tend to be replenished more frequently than necessary by consumers due to their low foaming level.

[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 parameter of the applicant's invention described herein and claimed.

[0027] Unless otherwise specifically stated, all proportions are based on the total weight of the composition, as is evident from the context. Unless otherwise specifically stated, all ratios are weight ratios, and all measurements are taken at 25°C unless otherwise specified.

[0028] Process for creating concentrated surfactant blends This process is used to produce a concentrated surfactant blend. The concentrated surfactant blend comprises an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof.

[0029] The process is a) A step of providing an alkyl alcohol stream containing at least one alkyl alcohol, b) A sulfation step in which at least one alkyl alcohol in an alkyl alcohol stream is sulfated to form an alkyl sulfuric acid stream containing at least one alkyl sulfuric acid, c) A step of providing a neutralizing stream containing at least one neutralizing agent, d) A neutralization step is included in which the alkyl sulfate stream and the neutralization stream are combined to neutralize the alkyl sulfate, A buffering surfactant is added before or during the neutralization process.

[0030] The buffering surfactant is added in a concentration that provides a concentrated surfactant blend having a pre-alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalinated water at 20°C using the method 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 desalinated water at 20°C.

[0031] Buffering capacity is the ability to neutralize pH and its resistance to pH changes caused by small amounts of acidic or basic inflow or outflow. If a system is not sufficiently buffered, even the addition of a small amount of acid or base will significantly change its pH, but if the system is sufficiently buffered, the same addition will hardly change its pH.

[0032] Pre-alkalinity is a commonly used industrial measure to indicate the amount of alkaline components present in a product. In some compositions, such as the concentrated surfactant blends disclosed herein, knowing the pre-alkalinity of a blend is more important than its buffering capacity, as it provides a measure of the blend's ability to neutralize any acids present or formed in the insights and thus maintain an alkaline pH.

[0033] Alkyl alcohol flow The processes described herein include a step of providing an alkyl alcohol stream. The alkyl alcohol stream comprises at least one alkyl alcohol. The alkyl alcohol stream itself may contain one alkyl alcohol, or alternatively, a blend of alkyl alcohols.

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

[0035] The alkyl chains of an alkyl alcohol or a 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%, and 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 produce the alkyl sulfate surfactant is at least 57 / 43, preferably 60 / 40 to 90 / 10, more preferably 60 / 40 to 80 / 20, and most preferably 60 / 40 to 70 / 30, foam persistence is particularly improved, especially in the presence of oily contaminants, while foam persistence in the presence of particulate matter is not impaired.

[0036] The relative molar amounts of C13 and C12 alkyl chains in an alkyl alcohol or a 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 alkyl alcohols used to prepare alkyl sulfated anionic surfactants can also 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] Alkyl alcohols or blends of alkyl alcohols may be alkoxylated or not. If it is desirable that the resulting concentrated surfactant blend contains alkylalkoxylated sulfates, at least one alkyl alcohol in the alkyl alcohol stream is preferably alkoxylated before the sulfation step. The alkyl alcohols may be blends of alkyl alcohols that are first blended together and then alkoxylated together to obtain the desired average degree of alkoxylation. Alternatively, one or more alcohols may be alkoxylated first, and then the alkoxylated alcohols or alcohol blend may be mixed to achieve the desired average degree of alkoxylation. In the first case, a unimodal distribution of alkoxylation is typically achieved, while in the second case, the alkoxylation distribution is typically multimodal.

[0038] When alkoxylylated, 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, in order for the resulting alkyl sulfate anionic surfactant to improve the physical stability at low temperatures and improve foam persistence of the composition of the present invention. However, in order to provide improved oil-cleaning properties of the resulting alkyl sulfate anionic surfactant, the average degree of alkoxylylation (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 alkoxylylated. When alkoxylylated, 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). Therefore, when calculating the molar average degree of alkoxylation, the moles of non-alkoxylated alkyl alcohols are included. Molar average degree of alkoxylation = (x1 * Degree of alkoxylation of alkyl alcohol 1 +x2 * Degree of alkoxylation of alkyl alcohol 2 + ....) / (x1 + x2 + ....) In the formula, x1, x2, ... are the number of 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 alkylalkoxy alcohol preferred for use in preparing alkyl sulfate surfactants is alkylethoxy alcohol.

[0041] The performance characteristics, including oil and grease cleaning, foaming, low-temperature stability, and viscosity of the final product, may be influenced by the width of the alkoxylation distribution of the resulting alkoxylated alkyl sulfate anionic surfactant. The alkoxylation distribution, including its width, can be altered through the selection of catalysts and process conditions when producing alkoxylated alkyl alcohols.

[0042] While not bound by theory, when alkoxylation of alkyl alcohols, such as ethoxylation, is desired, the amount of 1,4-dioxane byproducts in the alkoxylated, particularly ethoxylated alkyl sulfate, can be reduced by strictly controlling the processing conditions and raw material composition during both the alkoxylation, especially the ethoxylation and sulfation steps. Based on recent technological advances, further reduction of 1,4-dioxane byproducts can be achieved by subsequent stripping, distillation, solvent evaporation, centrifugation, microwave irradiation, molecular sieving, or catalytic or enzymatic decomposition steps. Processes for controlling the 1,4-dioxane content in alkoxylated / ethoxylated alkyl sulfates are widely known in the art. Alternatively, control of the 1,4-dioxane concentration 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, a mixture of 3-alpha-hydroxy-7-oxo stereoisomers of cholanaic 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 degree of branching of 15% to 50%, preferably 20% to 40%. The use of such branched alkyl alcohol can improve the low-temperature stability of the resulting alkyl sulfate surfactant composition and provide the desired oil and grease cleaning performance.

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

[0045] Such compositions require less solvent to achieve good physical stability at low temperatures. While greater branching of the surfactant also leads to faster initial foam formation, it typically results in lower foam persistence. The weight-average branching described herein has been found to improve low-temperature stability, initial foam formation, and foam life in liquid detergent compositions containing alkyl sulfate surfactants formed from such alkyl alcohols.

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

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

[0048] Non-C2 branching means that the alkyl chain has branching at multiple carbon positions along the alkyl chain backbone, or that it contains a single branching group located at a branching position on the alkyl chain other than the C2 position.

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

[0050] Non-C2 branched alkyl alcohols may contain isomers with single branches at more than 2-position branches, comprising at least 50% by weight, preferably 60-90% by weight, and more preferably 70-80% by weight of the non-C2 branched alkyl alcohol. This means that the branch is more than two carbon atoms away from the hydrophilic head group as defined above. Non-C2 alkyl alcohols may contain polybranched isomers of 5%-30% by weight, preferably 7%-20% by weight, and more preferably 10%-15% by weight of the non-C2 branched alkyl alcohol. Non-C2 alkyl alcohols may contain cyclic isomers of 5%-30% by weight, preferably 7%-20% by weight, and more preferably 10%-15% by weight of the non-C2 branched alkyl alcohol. The acyclic branching group can be selected from C1-C5 alkyl groups and mixtures thereof, if applicable.

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

[0052] The weight-average degree of branching and branching distribution can usually be obtained from the technical data sheet of the surfactant or the alkyl alcohol that constitutes it. Alternatively, branching can also 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 trademark Neodol®, or by Sasol under the trademarks Lial®, Isalchem®, and Safol®, or some of the natural alcohols produced by Procter & Gamble Chemicals. Alcohols (and alkoxylated alcohols) can be blended to achieve desired mole fractions of C12 and C13 chains and desired C13 / C12 ratios, 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] Alkyl alcohols can contain essentially linear or perfectly linear alkyl chains, which are blended with branched alcohols to achieve a desired degree of branching. Preferred sources of naturally occurring alkyl chains include those derived from palm kernels and coconuts, with palm kernel-derived alkyl chains being more preferred. Naturally occurring alkyl chains can be fractionated to yield a desired mean alkyl chain length and to adjust the alkyl chain length distribution. The C12-C14 fraction is often referred to as the mid-cut fraction within naturally occurring alkyl chains. Alternatively, essentially linear alkyl chains can be synthetically extracted using the Ziegler process or its derivatives, methods for producing aliphatic alcohols from ethylene using organoaluminum compounds. The reaction produces linear primary alcohols having even carbon chains. Here again, the C12-C14 alkyl fraction is preferred and can be fractionated from the whole Ziegler alcohol.

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

[0056] The sulfation of alcohols or alkoxylated alcohols to (alkoxylated) alkyl sulfates is widely described. Further details of such sulfation processes are described 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] While various reagents can be used in the sulfation process, sulfur trioxide (SO3) is particularly preferred, at least in part, due to its low cost. SO3 is an electrophile that reacts rapidly with any organic compound containing an electron-donating group. The resulting reaction is highly exothermic. Effective cooling of the reactants is essential, as high temperatures promote side reactions that produce undesirable byproducts. Precise control of the molar ratio of SO3 to alkyl alcohol is also crucial, as excess SO3 contributes to side reactions and byproduct formation due to its reactivity. Therefore, commercial-scale sulfation reactions require special equipment and instrumentation that allow for strict control of the molar ratio of SO3 to alkyl alcohol and rapid removal of reaction heat.

[0058] Problems with SO3 reactivity have typically been solved by diluting and / or complexing SO3 to slow the reaction rate. Commercially available diluents or complexing agents include ammonia (sulfamic acid), hydrochloric acid (chlorosulfonic acid), and dry air (air / SO3 film sulfation). Improved product quality can be achieved by using any of these reagents, by controlling the ratio of SO3 to alkyl alcohol.

[0059] The air / SO3 membrane sulfation process is typically carried out using membrane reactors such as a cyclic drip-through membrane reactor, such as a "Chemithon" reactor, or a multi-tube membrane reactor, such as a "Ballestra" reactor. In such processes, SO3 is first diluted with dry air. This air / SO3 sulfation process is a direct process in which gaseous SO3 is diluted with very dry air and reacted directly with the alkyl alcohol feedstock. The reaction between gaseous SO3 and alkyl alcohol is rapid and stoichiometric. Although such processes are complicated by the possibility of side reactions, very high-purity alkyl sulfate surfactants can be achieved with strict process control.

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

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

[0062] Alkyl alcohols or blends of alkyl alcohols are converted to alkyl sulfuric acid via reaction with SO3 in a bottom-flow membrane reactor. Given the exothermic nature of the sulfonation reaction, further cooling is required after separating the atmosphere / gas from the liquid flow. Ideally, the reaction mixture is maintained at a temperature of 15°C to 50°C, preferably 30°C to 40°C, at the reactor outlet.

[0063] Atmosphere / gas can be separated from the liquid using a liquid separator. If sufficient gas is not removed from the liquid mixture by separation, an additional degassing step can be performed, for example, by using a "Fryma" rotary disk degasser.

[0064] The exhaust gas typically contains small amounts of unconverted SO2, unreacted SO3, and some contaminating 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 washed away from the process atmosphere in a scrubber using a dilute caustic solution.

[0065] To minimize sulfuric acid formation and maintain low ionic strength, the alkyl alcohol stream supplied to the sulfation reaction preferably contains less than 0.1%, preferably less than 0.05%, of water, and more preferably contains no water.

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

[0067] Neutralization Given the sensitivity of protonated alkyl sulfates to rehydrolysis of starting alkyl alcohols, a neutralization step is consequently required. Without neutralization, rehydrolysis of alkyl sulfates results in a decrease in the alkylsulfated anionic surfactant content in the resulting concentrated surfactant blend, and an increase in sulfate content, leading to discoloration of the concentrated surfactant blend and the liquid detergent composition prepared using the concentrated surfactant blend.

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

[0069] Too low a pH can lead to the re-hydrolysis of alkyl sulfated anionic surfactants, while too high a pH typically complicates the conversion of concentrated surfactant blends to the final detergent product composition, requiring, for example, a significant amount of acid to return the pH to the target final product pH. In addition, too high a pH can lead to the generation of 1,4-dioxane over time, along with the addition of more neutralizing agents, resulting in a corresponding increase in the salt concentration in the concentrated surfactant blend. Concentrated surfactant blends with high salt concentrations are more difficult to incorporate into detergent compositions, resulting in reduced low-temperature stability and increased viscosity upon initial dissolution in water, which in turn slows the dissolution of the product.

[0070] The neutralizing agent is an alkali. Further neutralizing agents may 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 the most preferred. Alternatively, or in addition, other alkalis may be added as part of the neutralization step. Particularly preferred other alkalis are those that can be added to the resulting liquid detergent composition to improve performance. In particular, amines, especially cyclic polyamines having amine functional groups that aid in cleaning, as will be discussed later.

[0071] The neutralization step must 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 preferred 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 may be used. A loop reactor is typically a continuous tube or pipe of stainless steel, with the outlet of a recirculation pump connected to its inlet. The reactants are fed into the loop where neutralization takes place, and the mixture, at least partially neutralized, is removed from the loop.

[0073] Therefore, loop reactors typically include a circulation pump, a crusher or high-shear mixer, and a heat exchanger due to the exothermic nature of the neutralization reaction. Efficient mixing of the alkyl sulfuric acid stream and the neutralization stream results in an instantaneous reaction, avoiding undesirable decomposition reactions in isolated spots and pH tendencies that occur during the neutralization process. For this reason, high-shear mixers are typically used, especially considering the high viscosity of pastes obtained at low shear rates.

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

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

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

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

[0078] Buffering surfactants are preferably added during the neutralization step to ensure that the resulting mixture quickly reaches the desired pH and avoids the aforementioned hydrolysis.

[0079] The neutralizing flow may include other optional components, such as nonionic surfactants, polymers, and peroxides, as described below, as well as mixtures thereof.

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

[0081] Buffering surfactants: The buffering surfactant is preferably added as a separate buffering stream during the neutralization step, but is also preferably added as part of the neutralization stream. Alternatively, the buffering surfactant can be added before the neutralization step. The alkyl sulfate and buffering surfactant can 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.

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

[0083] Buffering surfactants are amphoteric surfactants, zwitterionic surfactants, or mixtures thereof. Preferred buffering 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 buffering surfactants also contribute to the performance of the resulting liquid handwashing dishwashing detergent. In addition, buffering surfactants result in a concentrated surfactant blend formed by the processes described herein, having reduced viscosity, especially when amine oxide surfactants are used as buffering surfactants.

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

[0085] Suitable amine oxide surfactants may be linear or branched, but linear is preferred. Suitable linear amine oxides are typically water-soluble and characterized by the formula R1-N(R2)(R3)O (wherein R1 is a C8-18 alkyl group, and the R2 and R3 portions are selected from the group consisting of C1-3 alkyl groups, C1-3 hydroxyalkyl groups, and mixtures thereof). For example, R2 and R3 can be selected from the group consisting of methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl, and 3-hydroxypropyl, and mixtures thereof, but it is preferable that one or both of R2 and R3 are methyl. Examples of linear amine oxide surfactants include linear C10-C18 alkyldimethylamine oxides and linear C8-C12 alkoxyethyl dihydroxyethylamine oxides.

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

[0087] A suitable alternative amine oxide surfactant is a moderately branched amine oxide surfactant. As used herein, “moderately branched” means that the amine oxide has one alkyl moiety having n1 carbon atoms, and one alkyl branch in the alkyl moiety has n2 carbon atoms. The alkyl branch is located on the nitrogen to alpha carbon on the alkyl moiety. This type of branching of amine oxide is also known in the art as internal amine oxide. The sum of n1 and n2 may be 10 to 24, preferably 12 to 20, more preferably 10 to 16 carbon atoms. The number of carbon atoms in one alkyl moiety (n1) is preferably the same as or similar to the number of carbon atoms in one alkyl branch (n2), so that the alkyl moiety and its 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 moderately branched amine oxide used herein, |n1-n2| has 5 or fewer, preferably 4, and most preferably 0 to 4 carbon atoms. The amine oxide further comprises two portions independently selected from a C1-3 alkyl group, a C1-3 hydroxyalkyl group, or a polyethylene oxide group containing an average of about 1 to about 3 ethylene oxide groups. Preferably, these two portions are selected from C1-3 alkyl groups, and more preferably, both are selected as C1 alkyl groups.

[0088] Alternatively, the amine oxide surfactant may be a mixture of amine oxides, including a mixture of low-cut amine oxides and mid-cut amine oxides. Therefore, the amine oxides in the composition of the present invention are a) A low-cut amine oxide of formula R1R2R3AO in an amount of approximately 10% to approximately 45% by weight of amine oxide, 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% by weight to 90% by weight of the total amine oxide of a mid-cut amine oxide of formula R4R5R6AO, wherein 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 oxide preferred for use herein, R3 is n-decyl, and preferably both R1 and R2 are methyl. In the mid-cut amine oxide of formula R4R5R6AO, preferably both R4 and R5 are methyl.

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

[0091] Suitable zwitterionic surfactants include betaine surfactants. Such betaine surfactants include alkyl betaines, alkylamidobetaines, amidoazolinium betaines, sulfobetaines (INCI sultaines), and phosphobetaines, 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 between 1 and 10, preferably between 2 and 5, more preferably between 3. x is 0 or 1, preferably 1. R2 and R3 are independently selected from the group consisting of C1-4 alkyl residues, substituted hydroxyl such as hydroxyethyl, and mixtures thereof, preferably both R2 and R3 are methyl. m is an integer between 1 and 4, preferably 1, 2, or 3. y is either 0 or 1. Y is selected from the group consisting of COO, SO3, OPO(OR5)O, or P(O)(OR5)O (wherein R5 is H or a C1-4 alkyl residue).

[0092] Preferred betaines are alkylbetaine of formula (Ia), alkylamidopropylbetaine of formula (Ib), sulfobetaine of formula (Ic), and amidesulfobetaine 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 the carbobetaines of formulas (Ia) and (Ib) [i.e., in formula (I), Y- is COO-], and more preferred is the alkylamide betaine of formula (Ib).

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

[0094] In the neutralization step, at least one alkyl sulfate and a buffering surfactant can 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] Therefore, 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 sulfuric acid at the start of the neutralization step. The amount of unreacted alkyl (alkoxylated) alcohol can be determined by GC analysis (after neutralization of alkyl sulfuric acid).

[0096] Buffering surfactants can be added to a flow further containing peroxides, particularly when amine oxides are used as buffering surfactants. The peroxides may be present such that the flow containing the buffering surfactant has a residual peroxide concentration of 5.0 ppm to 300 ppm, preferably 40 ppm to 80 ppm, per 1 part by weight of the buffering surfactant. If the concentrated surfactant blend contains ethoxylated alkyl sulfate surfactants, the presence of peroxides is considered to further limit the formation and growth of 1,4-dioxane in the concentrated surfactant blend formed by this process.

[0097] Any further steps If desired, auxiliary components such as those described below may be added before, during, or after neutralization to simplify the preparation of the final liquid detergent composition. Other optional components include water, organic solvents, pH adjusters, further surfactants, polymers, amines, preservatives, and mixtures thereof. Preferred further surfactants include further anionic surfactants, nonionic surfactants, and mixtures thereof.

[0098] Alkyl sulfate-containing concentrated surfactant blend The resulting concentrated surfactant blend comprises 30% to 70% by weight, preferably 40% to 60% by weight, more preferably 45% to 55% by weight of alkyl sulfated anionic surfactant and 1.0% to 25% by weight, preferably 5.0% to 20% by weight, more preferably 10% to 15% by weight of buffering surfactant. The concentrated surfactant blend contains alkyl sulfated anionic surfactant, which has an average degree of alkoxylation of less than 0.5, preferably less than 0.1, and more preferably is not alkoxylated. If alkoxylation occurs, the alkoxylation is preferably ethoxylation.

[0099] Buffered surfactants buffer the pH of concentrated surfactant blends without the need to introduce additional salts during blending. Therefore, concentrated surfactant blends resist pH changes caused by the addition or formation of acids (or bases). The resulting buffer reduces alkyl sulfate concentrations, for example, when degraded by contact with air, but also prevents the formation of by-products (e.g., HSO4) that cause browning of the concentrated surfactant blend. - This reduces the risk of hydrolysis of alkyl sulfate surfactants due to a decrease in pH, which also leads to the formation of ions. Furthermore, without buffering, a higher pH is required for concentrated surfactant blends to avoid the pH decreasing over time to a level where the hydrolysis of alkyl sulfate surfactants occurs quite rapidly. The need to add additional alkali results in a higher ionic strength for unbuffered concentrated surfactant blends. This leads to a decrease in the processability of concentrated surfactant blends, as well as decreased dispersibility and viscosity upon dilution, and reduced foaming and foam persistence of compositions containing such unbuffered concentrated surfactant blends.

[0100] A buffer for a specific application must be effective at the desired pH and, if necessary, also provide sufficient buffering capacity to maintain the desired pH. To inhibit hydrolysis and minimize the formation of 1,4-dioxane, the resulting concentrated surfactant blend formed by the process described herein preferably has a buffering range of pH 7.0–7.8.

[0101] The effectiveness of the buffering system is measured by its pre-alkalinity. Pre-alkalinity is essentially the ability of the composition to neutralize acidic residues formed in the composition by the hydrolysis of alkyl sulfate surfactants, etc. The buffering surfactant is added at a concentration that provides the resulting concentrated surfactant blend having a pre-alkalinity greater than 0.02, preferably 0.04 to 0.50, and more preferably 0.06 to 0.30, when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C using the method described herein.

[0102] Alkyl sulfated anionic surfactants and buffering surfactants can be present in the concentrated surfactant mixture in a weight ratio of 10:1 to 1:1, preferably 8:1 to 2:1, and more preferably 6:1 to 3:1.

[0103] This process, utilizing buffered surfactants, has been found to enable a lower pH in the concentrated surfactant blend. As a result, lower concentrations of 1,4-dioxane are present in the concentrated surfactant blend. Furthermore, the resulting alkyl sulfate-containing concentrated surfactant blend exhibits a low rate of increase in 1,4-dioxane byproduct concentration due to degradation. Therefore, the dioxane concentration in the concentrated surfactant blend formed by the process of the present invention may be less than 40 ppm, preferably less than 30 ppm, and most preferably less than 15 ppm.

[0104] The concentrated surfactant blend may contain further surfactants. Suitable further surfactants include additional anionic surfactants, such as sulfonate anionic surfactants like HLAS, or sulfosuccinate anionic surfactants. However, in preferred processes, the amount of such further anionic surfactants is kept low. In more preferred processes, no further anionic surfactants are added. Therefore, the concentrated surfactant blend may contain at least 70% by weight, preferably at least 85% by weight, and more preferably 100% by weight of alkylsulfated anionic surfactants, relative to the anionic surfactant. Since such fatty acids interfere with foam formation, the concentrated surfactant blend preferably does not contain fatty acids or their salts.

[0105] Further suitable surfactants include nonionic surfactants. The concentrated surfactant blend may further contain nonionic surfactants. Suitable nonionic surfactants include alkoxylated alcohol nonionic surfactants, alkyl polyglucoside nonionic surfactants, and mixtures thereof.

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

[0107] Preferably, the alkoxylated alcohol nonionic surfactant is a linear or branched primary or secondary alkylalkoxylated nonionic surfactant, preferably an alkylethoxylated nonionic surfactant, which preferably contains an average of 9 to 15 carbon atoms, preferably 10 to 14 carbon atoms, 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 contain alkyl polyglucoside ("APG") surfactants. The addition of alkyl polyglucoside surfactants has been shown to improve foaming beyond that of comparative nonionic surfactants such as alkyl ethoxylated nonionic surfactants. If present, alkyl polyglucoside may be present in the concentrated surfactant blend at a concentration of 0.5% to 20% by weight, preferably 0.75% to 15% by weight, more preferably 1% to 10% by weight, and most preferably 1% to 5% by weight of the total surfactants 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 has an average degree of polymerization of preferably 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 suppliers (for example, Simusol® surfactant 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 may have a pH of 7.1–10, preferably 7.3–9.5, more preferably 7.5–9.0, when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C. Too low a pH can lead to re-hydrolysis of alkyl sulfates, while too high a pH typically complicates the conversion of the concentrated surfactant blend into the final detergent product composition, requiring, for example, a considerable amount of acid to return the pH to the target final product pH. In addition, too high a pH can lead to the generation of 1,4-dioxane over time, requiring the addition of more neutralizing agents, which in turn can lead to an increase in the salt concentration in the concentrated surfactant blend. Concentrated surfactant blends with high salt concentrations are more difficult to incorporate into detergent compositions, resulting in reduced low-temperature stability and increased viscosity upon initial dissolution in water, thus slowing the dissolution of the product.

[0111] The concentrated surfactant mixture can be Newtonian or non-Newtonian, and is preferably Newtonian. The surfactant blend is 10s -1 When measured at a shear rate and a temperature of 20°C, it can have a viscosity 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.

[0112] The concentrated surfactant blend may have a flow index of 0.1 to 1.0, preferably 0.2 to 0.5, and 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, and 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. As a result, 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 can be measured using differential scanning calorimetry (DSC).

[0114] The concentrated surfactant blend measured at a temperature of 20°C and yielded 500 kg / m³. 3 ~1,500 kg / m 3 Preferably 750 kg / m 3 ~1,250 kg / m 3 , comfortably 1,000 kg / m 3 ~1,100 kg / m 3 It can have a density within the range of [this range]. The density can be measured using any preferred means, such as using a pycnometer.

[0115] Liquid dishwashing composition for hand washing The concentrated surfactant blends described herein can be used to prepare liquid detergent compositions, in particular liquid handwashing dishwashing detergent compositions.

[0116] As used herein, the terms “dishes” and “tableware” include, in a non-limiting sense, cookware and tableware made from ceramics, porcelain, metal, glass, plastics (e.g., polyethylene, polypropylene, polystyrene, etc.) and wood.

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

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

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

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

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

[0122] A liquid hand-washing dishwashing detergent composition contains an anionic surfactant included in a concentrated surfactant blend used to prepare the detergent composition. Preferably, the liquid hand-washing dishwashing detergent composition does not contain any further anionic surfactants.

[0123] A liquid hand-washing dishwashing detergent composition contains a buffering surfactant, or a cosurfactant comprising such a buffering surfactant, which is included in the concentrated surfactant blend used to prepare the detergent composition. Further cosurfactants may be added in addition to the cosurfactants included in the concentrated surfactant blend. The liquid hand-washing dishwashing detergent composition may also contain a nonionic surfactant. Suitable nonionic surfactants include, as mentioned above, alkoxylated alcohol nonionic surfactants, alkyl polyglucoside nonionic surfactants, and mixtures thereof. Such nonionic surfactants may be added as part of the concentrated surfactant blend used to prepare the detergent composition, or added separately in addition to the concentrated surfactant blend, or both.

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

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

[0126] A preferred amphiphilic alkoxylated polyethyleneimine polymer has the general structure of formula (I),

[0127] [ka] In the formula, the polyethyleneimine main chain has a weight-average molecular weight of 600, n in formula (I) is average 10, m in formula (I) is average 7, 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% to 22% of the nitrogen atoms in the polyethyleneimine backbone. The molecular weight of this amphiphilic alkoxylated polyethyleneimine polymer is preferably 10,000 to 15,000 Da.

[0128] More preferably, the amphiphilic alkoxylated polyethyleneimine polymer has the general structure of formula (I), wherein the polyethyleneimine skeleton has a weight-average molecular weight of 600 Da, n in formula (I) is average 24, m in formula (I) is average 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% to 22% of the nitrogen atoms of the polyethyleneimine skeleton, preferably 0%. The molecular weight of this amphiphilic alkoxylated polyethyleneimine polymer is preferably 25,000 to 30,000, most preferably 28,000 Da.

[0129] Amphiphilic alkoxylated polyethyleneimine polymers can be prepared by the method described in detail in International Publication No. 2007 / 135645.

[0130] Cyclic polyamines The composition may contain a cyclic polyamine having an amine functional group that aids in cleaning. The composition of the present invention preferably contains 0.1% to 3% by weight, more preferably 0.2% to 2% by weight, and particularly 0.5% to 1% by weight of a cyclic polyamine.

[0131] Cyclic polyamines have at least two primary amine functional groups. While the primary amines may be located at any position within the cyclic amine, it has been found that better performance is obtained when the primary amines are located at positions 1 and 3, from the viewpoint of grease and oil cleaning. It has also been found that cyclic amines in which one substituent is -CH3 and the rest are H atoms provide improved grease and oil cleaning performance.

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

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

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

[0135] Triblock copolymer The compositions of the present invention may contain triblock copolymers. The triblock copolymer may be present in a concentration of 0.1% to 10% by weight, preferably 0.5% to 7.5% by weight, and more preferably 1% to 5% by weight of the whole 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 x represents the number of EO units in each EO block. Each x can be independently 5 to 50 on average, preferably 10 to 40, and 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 at most 2 units, preferably at most 1 unit, and more preferably both x have the same number of units. PO represents propylene oxide and y represents the number of PO units in the PO block. Each of the values ​​of y can be on average 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. Preferably, the ratio of y to the average x of the two EO blocks in the triblock copolymer is 3:1 to 2:1. Preferably, the triblock copolymer has an average weight percentage of all EO that is 30% to 50% by weight of the triblock copolymer. Preferably, the triblock copolymer has an average weight percentage of all 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 in the case of the triblock copolymer is 100%. The triblock copolymer can have an average molecular weight of 2060 to 7880, preferably 2620 to 6710, more preferably 2620 to 5430, and most preferably 2800 to 4700. The average molecular weight is determined using 1H NMR spectroscopy (see Thermo Scientific Application Note No. AN52907).

[0137] A triblock copolymer has a basic structure ABA, where A and B are different homopolymer and / or monomer units. In this case, A is ethylene oxide (EO) and B is propylene oxide (PO). Those skilled in the art will recognize that the term “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 retention performance and / or foam consistency throughout dilution in liquid hand-washing dishwashing detergent compositions in the presence of oily stains.

[0139] Suitable EO-PO-EO triblock copolymers are commercially available, for example, from BASF as the Pluronic® PE series and from Dow Chemical Company as the Tergitol® L series. Particularly preferred triblock copolymers from BASF are sold under the trademark names Pluronic® PE6400 (approximately 2900 MW, approximately 40% by weight EO) and Pluronic® PE9400 (approximately 4600 MW, approximately 40% by weight EO). Particularly preferred triblock copolymers from Dow Chemical Company are sold under the trademark name Tergitol® L64 (approximately 2700 MW, approximately 40% by weight EO).

[0140] Preferred triblock copolymers readily biodegrade under aerobic conditions.

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

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

[0143] Hydrotrope: The composition of the present invention may contain 0.1% to 10% by weight, preferably 0.5% to 10% by weight, or more preferably 1% to 10% by weight, of hydrotrope or a mixture thereof, preferably sodium cumenesulfonate.

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

[0145] auxiliary ingredients The cleansing composition may optionally contain a builder (preferably citrate), and many other auxiliary components such as chelating agents, conditioning polymers, other cleansing polymers, surface modifying polymers, structuring agents, emollients, wetting agents, skin rejuvenating active substances, enzymes, carboxylic acids, scrub particles, fragrances, odor suppressants, pigments, dyes, opacifiers, pearlescent particles, inorganic cations such as alkaline earth metals like Ca / Mg ions, antibacterial agents, preservatives, antioxidants, viscosity modifiers (e.g., salts such as NaCl and other monovalent, divalent, and trivalent salts), and pH adjusters and buffering means (e.g., carboxylic acids such as citric acid, HCl, NaOH, KOH, alkanolamines, sodium carbonate, bicarbonates, sesquicarbonates, and other carbonates).

[0146] If present, the composition contains 0.01% to 2.0% by weight, preferably 0.05% to 1.5% by weight, or more preferably 0.1% to 1.0% by weight of alkaline earth metal ions, with magnesium ions and / or calcium ions being particularly preferred. The liquid detergent composition may also contain transition metal ions at lower concentrations, such as up to 1.0% by weight or up to 0.5% by weight of the composition.

[0147] Packaged Products The dishwashing detergent composition for hand washing can be packaged in a container, typically a plastic container. A suitable container includes an orifice. Typically, the container has a cap, and the orifice is typically located on the cap. The cap may have a spout, and the orifice is located at the outlet of the spout. The spout may have a length of 0.5 mm to 10 mm.

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

[0149] The container can typically contain a liquid hand-washing dishwashing detergent composition in an amount of 200 ml to 5,000 ml, preferably 350 ml to 2,000 ml, and more preferably 400 ml to 1,000 ml.

[0150] Alternatively, hand-washing dish soap compositions can be packaged in inverted containers. Such inverted containers typically have a cap at the bottom of the container, which includes either a lid or a self-sealing valve, or a combination thereof. The cap preferably includes a self-sealing valve. A suitable self-sealing valve is a slit valve. The self-sealing valve defines an orifice that opens in reaction when the pressure inside the valve exceeds the pressure outside the valve. Bottom-shaped dispensing containers may include an impact-resistant system, such as that described in International Publication No. 2019108293(A1).

[0151] Cleaning method The resulting liquid detergent composition can be used for manual cleaning. A preferred method includes the steps of supplying such a liquid detergent composition to a certain volume of water to form a cleaning solution, and immersing the dishes in the cleaning solution. The dishes are cleaned with the composition in the presence of water. The dishes may also be rinsed. In this specification, “rinsing” means bringing the dishes cleaned by the process according to the present invention into contact with a considerable amount of a suitable solvent, typically water. “Considerable amount” usually means about 1 to about 20 liters or under running water.

[0152] The compositions described herein may be applied in their diluted form. Soiled dishes are brought into contact with an effective amount, typically about 0.5 mL to about 20 mL, preferably about 3 mL to about 10 mL, of the detergent composition of the present invention diluted with water (for about 25 dishes to be processed), preferably in liquid form. The actual amount of cleaning composition used is at the user's discretion and typically depends on factors such as the formulation of specific products of the cleaning composition, including the concentration of the 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 thus diluted cleaning composition, the soiled surfaces of the dishes are brought into contact with a cloth, sponge, or similar cleaning tool. The cloth, sponge, or similar cleaning tool may be immersed in a mixture of the cleaning composition and water before contact with the dishes, typically for a period ranging from about 1 to about 10 seconds, although the actual time will vary depending on the application and user. Contacting the cloth, sponge, or similar cleaning tool with the dishes involves simultaneously scrubbing the dishes.

[0153] Preferably, the composition in its undiluted form is applied to the dishes to be processed. “In its undiluted form” means, as used herein, that the composition is applied directly to the surface to be processed, or to a cleaning device or tool such as a brush, sponge, nonwoven or woven material, without any significant dilution by the user before application (immediately before). Application using a sponge is preferred. “In its undiluted form” also includes, for example, slight dilution due to the presence of water on the surface of the cleaning device, or the addition of water by the consumer to remove any remaining amount of the composition from the bottle. Therefore, the composition in its undiluted form includes a mixture of 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, and even more preferably 90:10 to 100:0, depending on the user’s habits and cleaning operations.

[0154] Test method A) pH: pH is measured as a 10% aqueous solution in desalinated water at 20°C using a pH meter such as the 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 buffers.

[0155] B) Preliminary alkalinity: Preliminary alkalinity is defined as the amount of grams (NaOH) per 100g (composition) required to titrate a pH 7.0 test composition to the pH of the test composition. The preliminary alkalinity of the solution is measured as follows:

[0156] Preliminary alkalinity is measured using a 10% solution of the concentrated surfactant blend in deionized water at 20°C. Thus, 50 g of the concentrated surfactant blend is diluted to 10% with deionized water and mixed for 5 minutes until completely homogenized. Then, 100 g of the 10% solution is 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 the endpoint of pH 4 is achieved, or until the maximum titration volume of the titrator (25 ml in the titrator described above) is reached. 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] The preliminary alkalinity is calculated as follows: Preliminary alkalinity = 0.1N HCl × 0.1 (equivalents / liter) × equivalent NaOH (g / equivalent) × 10, which is the amount of HCl needed to reach a pH of 7.0 ml.

[0158] When the maximum titration volume from the titrator is reached, the final pH is recorded, and the preliminary alkalinity relative to this pH is calculated. Subsequently, the preliminary alkalinity up to pH 7.0 can be estimated by linear extrapolation of the "pH vs. volume titrator" titration curve obtained between 20 ml and 25 ml of added titrant volumes to pH 7.0.

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

[0160] The upward shear rate sweep is 0.1s -1 ~100s -1 The measurement is performed in increments of 10 points every 10 seconds from the shear rate, with each increment automatically executed by the rheometer after the measurement stabilizes. Unless otherwise specified, viscosity is measured in 10s. -1 The shear rate is measured at a temperature of 20°C.

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

[0162] The upward shear rate sweep is 0.1s -1 ~100s -1The measurement is performed in increments of 10 points every 10 units of the shear rate, with each increment automatically executed by the rheometer after the measurement has stabilized.

[0163] The shear stress is recorded as a function of shear rate by a rheometer. Next, the Herschley-Buckley model: τ = τ0 + Kγ n Applying this to the formula, 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 of concentrated surfactant blend with temperature: The rheological variation due to temperature was measured using a "TA instruments DHR1" rheometer (TA instruments, serial number: SN999393) with a cone and plate configuration (flat steel Peltier plate and a 40mm diameter cone with a 2.026° angle) for 10 seconds. -1 Using a shear rate of 2°C / min and a temperature sweep from 60°C to 5°C, at 60°C for 10 seconds -1 Measurements are taken after a 100-second equilibrium process at the specified shear rate.

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

[0166] G) Foaming properties of the detergent composition: The initial foaming properties of the composition are 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 height of the solution is recorded.

[0167] Next, stir the solution at 5000 RPM for 5 seconds. 20 seconds after stirring stops, record the total height of the sample (foam + liquid solution). To calculate the foam height, subtract the initial solution height from the measured total height.

[0168] H) Foam persistence index: The purpose of the foam persistence test is to compare the change over time of foam volume generated for different test agents at specified water hardness, solution temperature, and formulation concentration while under the influence of intermittent fouling. The data are compared and expressed as a foam persistence index relative to a reference composition (the reference composition has a foam persistence index of 100). The procedure is as follows: 1. Dispense a 0.12% by weight test composition into a water stream at 35°C with water hardness levels of 0.36 mmol / L equivalent (2.0 gpg) of calcium carbonate, 1.25 mmol / L equivalent (7.0 gpg) of calcium carbonate, and 2.67 mmol / L equivalent (15 gpg) of calcium carbonate at a flow rate of 0.67 mL / second using a plastic pipette at a height of 37 cm above the bottom of a sink (dimensions: diameter 300 mm, height 288 mm). Fill the sink with this mixture until it reaches 4 L under 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 The value (represented by ) is recorded immediately after filling is complete. 3. Immediately pour a fixed amount (6 mL) of the following composition into the center of the sink. The resulting solution is mixed using a metal blade (10cm x 5cm) that rotates 20 times at 4.85 RPM and is positioned at a 45° angle to the gas-liquid interface in the center of the sink. 5. Record another measurement of the total foam volume immediately after the blade rotation ends. 6. The total measured foam volume is 400 cm³. 3 Repeat steps 3-5 until the following level is reached: 400cm 3 The amount of dirt added required to reach that level is considered to be the foam persistence of the test composition. 7. Each test composition is tested four times under the same test conditions (i.e., water temperature, composition concentration, water hardness, and type of dirt). 8. The average foam persistence is calculated by taking the average of four tests performed for each sample under the specified test conditions. 9. The average persistence of the test composition sample is compared to that of the reference composition sample, and the foam persistence index is calculated. The calculation is as follows:

[0169]

number

[0170] The grease stain composition used in the test is prepared by mixing the components listed in Table A in a standard manner.

[0171] [Table 1] [Examples]

[0172] The effects of alkyl sulfate neutralization in the presence of an amine oxide buffered surfactant (invention) and in the absence of an amine oxide buffered surfactant (comparison) on the rheology of the resulting concentrated surfactant blends, as well as on the dilution, foaming, and physical stability of the final product, were studied according to the test methods described herein. The buffered concentrated surfactant blends were prepared on a pilot plant scale by sulfating and neutralizing the substances in a fall membrane reactor using SO3 gas as described herein.

[0173] In the embodiments of the present invention, the neutralization stream was an aqueous solution of sodium hydroxide and C12-C14 dimethylamine oxide (as a buffering surfactant) at the concentrations shown in Table 1. In the comparative example, the neutralization stream was an aqueous solution of sodium hydroxide without the addition of a buffering surfactant.

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

[0175] Comparative Examples C to E used the same alkyl sulfuric acid as in Example 1 and Comparative Examples A and B of the present invention, but did not contain a buffering surfactant. Therefore, a higher concentration of sodium hydroxide was required to ensure a sufficiently high pH to achieve a strong preliminary alkalinity (to avoid re-hydrolysis of the alkyl sulfuric acid).

[0176] [Table 2] * comparison 1 50% branched C12-C13 alkyl sulfate produced from Safol® 23 alcohol, a Fischer-Tropsh derived alcohol supplied by Sasol. 2 55% branched C12-C13 alkyl sulfate produced from Lial (trademark) 123 alcohol, an OXO alcohol supplied by Sasol. 3 Linear C12-C14 alkyl sulfates produced by P&G Chemicals from naturally derived 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 buffering surfactants had higher pre-alkalinity and therefore stronger robustness against re-hydrolysis of alkyl sulfate, despite the use of less alkali (sodium hydroxide). In addition, the smaller amount of alkali resulted in fewer salts present in the concentrated surfactant blend, resulting in a more stable and injectable viscosity.

[0178] Furthermore, as can be seen from the viscosity data, the concentrated surfactant blend of the present invention, which contains a buffering surfactant, has a viscosity profile that is easier to process, in contrast to the comparative composition that does not contain a buffering surfactant. Small differences in surfactant concentration between the examples of the present invention and the comparative examples do not result in a significant difference in the measured viscosity.

[0179] In fact, the concentrated surfactant blends of Comparative Examples D and E had a viscosity that was almost like a solid gel, and the viscosity was immeasurable. When water was added to these compositions to reach the same activity levels as Composition 1 of the present invention and Comparative Compositions A and B, Composition C entered the gel phase, while Composition D remained in the highly viscous gel phase, and the viscosity of both was immeasurable.

[0180] Example 2 is a reference example, and Comparative Examples F to H are further comparative examples (with a degree of branching outside the scope of the present invention) using different ratios of anionic surfactant and buffering surfactant.

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

[0182] The surfactant blend of Comparative Example B (see Table 1 above) was recreated (Comparative Example H) and incorporated into a detergent composition (Comparative Detergent Example B). Comparative Detergent Example A was formulated using a commercially available concentrated alkyl sulfate blend (Tensopol® S30LSHPH, commercially available from KLK Oleo) that does not contain buffering surfactants. Tensopol® S30LSHPH is a 30% activated sodium lauryl sulfate in liquid form with a high pH (pH greater than 11.0). The pH of detergent composition B was adjusted to 9.2 (using sodium hydroxide). The pH of comparative detergent composition A was adjusted to the same pH of 9.2 (using citric acid). The resulting compositions are shown in Table 3 below. The amine oxide concentrations shown for detergent composition B include the portion added with the concentrated surfactant blend of Comparative Example H and the portion added during subsequent composition preparation. Since the amount of alkali contained in the Tensopol(registered trademark) S30LSHPH starting material for detergent composition A is unknown, this has been marked as "unknown".

[0183] [Table 4]

[0184] To evaluate the dispersibility of the detergent compositions, detergent composition B (prepared using the process of the present invention but with comparative surfactant blend H made using an alcohol having a linear alkyl chain) and detergent composition A (comparative and prepared using a different process) were diluted with demineralized water to the concentrations shown in Table 3 below, and their viscosity was measured using the Brookfield viscosity test method described herein. The lower the viscosity at dilution, the more easily the composition disperses when added to a sink filled with water.

[0185] [Table 5]

[0186] As can be seen from the data above, compositions produced from concentrated surfactant blends prepared using the process of the present invention disperse more easily, even if they contain the same concentration of active ingredients and have essentially the same starting viscosity. Comparative detergent composition B above was prepared using a comparative surfactant blend with a degree of branching greater than the degree of branching required in the present invention (55%), but the improvement in viscosity upon dilution can be compensated for by using alkyl alcohols with the degree of branching required in the present invention for surfactant blends prepared using this process.

[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 this process, including albite containing anionic surfactants with a degree of branching exceeding the degree of branching required in the present invention, foam more easily, even if they contain the same concentration of active ingredients. Here again, comparative detergent composition B was made using a comparative surfactant blend with a degree of branching exceeding the degree of branching required in the present invention (55%), but the improvement in foaming can be extrapolated to surfactant blends made using this process with alkyl alcohols having the degree of branching required in the present invention.

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

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

[0192] As can be seen from the data above, the composition (detergent composition C) produced by the process of the present invention, using an alkyl alcohol with a weight-average degree of branching of 55%, foams more easily than comparable detergent compositions made using surfactant blends formed by conventional processes, exhibits improved freeze-thaw recovery despite containing the same concentration of active ingredients, and does not adversely affect foam persistence in the presence of grease and oil stains. Although comparative detergent composition C above was made using a comparative surfactant blend with a degree of branching exceeding the degree of branching required in the present invention (55%), the improvement in low-temperature stability can be compensated for by using an alkyl alcohol with the degree of branching required in the present invention for surfactant blends produced by this process.

[0193] The effect of branching with alkyl alcohols in this process is demonstrated 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 an even higher branching degree of 86.6%. Alcohol blends 1 (used in this invention), 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%) alcohol, and C12-14 linear (non-ethoxylated) alcohol, mixed in different ratios to achieve an average ethoxylation degree of 0.6 and the desired branching degree.

[0195] The sulfation process was carried out on a pilot plant scale by sulfating the material in a drip-feed reactor using SO3 gas.

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

[0197] The completion rate of the sulfation reaction was measured for each alcohol blend.

[0198] [Table 8] + The starting weight is C13 alcohol, and the remainder is linear alcohol.

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

[0200] It is known in the art that higher concentrations of SO3 are required to enhance the integrity of the reaction. Therefore, operation with high integrity is economically beneficial and results in a reduction in the concentration of unreacted alkyl alcohols. However, in conventional processes, the molar ratio of SO3 to alcohol must be increased beyond the stoichiometric ratio, which typically leads to 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, in which a buffering surfactant is added before or during the neutralization step, this additional salt is reduced to at least a small extent. As a result, the process of the present invention results in a higher reaction yield, less unreacted alkyl alcohol, and less salt. Both the reduction in unreacted alkyl alcohol and the reduction in salt concentration result in improved stability, particularly at low temperatures, of the resulting concentrated surfactant blends and the detergent compositions prepared using them.

[0202] The dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​listed. Instead, unless otherwise indicated, each such dimension is intended to mean both the listed value and the functionally equivalent range encompassing that value. For example, a dimension disclosed as "40 mm" is intended to mean "approximately 40 mm." [1] A process for producing a concentrated surfactant blend, wherein the concentrated surfactant blend comprises an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, and the process is a. A step of providing an alkyl alcohol stream containing at least one alkyl alcohol, wherein the alkyl alcohol in the alkyl alcohol stream has a weight-average branching degree of 15% to 50%. b. A sulfation step in which at least one alkyl alcohol in the alkyl alcohol stream is sulfurized to form an alkyl sulfuric acid stream containing at least one alkyl sulfuric acid, c. A step of providing a neutralizing stream containing at least one neutralizing agent. d. A neutralization step is included in which the alkyl sulfuric acid stream and the neutralization stream are combined in order to neutralize the alkyl sulfuric acid. The buffering surfactant is added before or during the neutralization step. The buffering surfactant is added at a concentration that provides the resulting concentrated surfactant blend having a preliminary alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C. The process wherein 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 desalinated water at 20°C. [2] The process according to [1], wherein the alkyl alcohol in the alkyl alcohol stream comprises a blend of alkyl alcohols. [3] The process according to [1] or [2], wherein the alkyl alcohol in the alkyl alcohol stream has a molar-average alkyl chain length of 8 to 18, preferably 10 to 14, and most preferably 12 to 13 carbon atoms. [4] The process according to any one of [1] to [3], wherein the alkyl alcohol in the alkyl alcohol stream has a weight-average branching degree of 20% to 40%. [5] The process according to any one of [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 includes 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 1.0:1 to 5:1, and more preferably 2:1 to 4:1. b. The process according to [5], wherein the non-C2 branched alkyl alcohol comprises less than 30% by weight, preferably less than 20% by weight, and more preferably less than 10% by weight of a C1 branched alkyl alcohol, and most preferably the non-C2 branched alkyl alcohol does not contain a C1 branched alkyl alcohol. [7] The process according to any one of [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 0.3 to 2.0, and more preferably 0.5 to 0.9. [8] The process according to any one of [1] to [7], wherein the sulfation step is carried out in a liquid-gas interface reactor, preferably a flow-through membrane reactor. [9] The process according to any one of [1] to [8], wherein the buffering surfactant is added during the neutralization step.

[10] The process according to any one of [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 alkyldimethylamine oxide, C12-14 alkylamidopropylamine oxide, and mixtures thereof.

[11] The process according to any one of [1] to

[10] , wherein the alkyl sulfuric acid and the buffering surfactant are 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.

[12] The process according to any one of [1] to

[11] , wherein during or after the neutralization step, the neutralizing agent is added in a concentration that provides the resulting concentrated surfactant blend having a pH of 7.3 to 9.5, more preferably 7.5 to 9.0, as measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C.

[13] The process according to any one of [1] to

[12] , wherein the buffering surfactant is added at a concentration that provides the resulting concentrated surfactant blend having a preliminary alkalinity of 0.04 to 0.50, more preferably 0.06 to 0.30, when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C.

[14] It is a concentrated surfactant blend, a. 30% to 70% by weight of alkyl sulfated anionic surfactant in the concentrated surfactant blend, wherein the alkyl sulfated anionic surfactant has an average degree of alkoxylation of less than 0.5 and a weight-average degree of branching of 15% to 50%. b. 1.0% to 25% by weight of a buffering surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, in the concentrated surfactant blend. Includes, A concentrated surfactant blend wherein the buffering surfactant is present at a concentration that provides the resulting concentrated surfactant blend having a pre-alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalinated water at 20°C, 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 desalinated water at 20°C.

[15] The aforementioned blend, a. The alkyl sulfated anionic surfactant in 40% to 60% by weight, preferably 45% to 55% by weight of the concentrated surfactant blend, b. The concentrated surfactant blend according to

[14] , comprising 5.0% to 20% by weight, preferably 10% to 15% by weight, of the concentrated surfactant blend, the buffered surfactant.

Claims

1. A process for producing a concentrated surfactant blend, wherein the concentrated surfactant blend comprises an alkyl sulfated anionic surfactant and a buffered surfactant selected from the group consisting of amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, and the process is a. A step of providing an alkyl alcohol stream containing at least one alkyl alcohol, wherein the alkyl alcohol in the alkyl alcohol stream has a weight-average branching degree of 15% to 50%. b. A sulfation step in which at least one alkyl alcohol in the alkyl alcohol stream is sulfurized to form an alkyl sulfuric acid stream containing at least one alkyl sulfuric acid, c. A step of providing a neutralizing stream containing at least one neutralizing agent. d. A neutralization step is included in which the alkyl sulfuric acid stream and the neutralization stream are combined in order to neutralize the alkyl sulfuric acid. The buffering surfactant is added before or during the neutralization step. The buffering surfactant is added at a concentration that provides the resulting concentrated surfactant blend having a preliminary alkalinity greater than 0.02 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C. The concentrated surfactant blend obtained, when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C, has a pH of 7.1 to 10. A process in which the buffered surfactant is added in a concentration that provides the resulting concentrated surfactant blend having a buffered pH range of 7.0 to 7.

8.

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

3. The process according to claim 1 or 2, wherein the alkyl alcohol in the alkyl alcohol stream has a molar-average alkyl chain length of 8 to 18 carbon atoms.

4. The process according to claim 1 or 2, wherein the alkyl alcohol in the alkyl alcohol stream has a molar-average alkyl chain length of 12 to 13 carbon atoms.

5. The process according to claim 1 or 2, 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.

6. The alkyl alcohol includes 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. b. The process according to claim 5, wherein the non-C2 branched alkyl alcohol comprises less than 30% by weight of a C1 branched alkyl alcohol.

7. The process according to claim 1 or 2, wherein at least one alkyl alcohol in the alkyl alcohol stream is alkoxylated to an average degree of alkoxylation of less than 3.

5.

8. The process according to claim 1 or 2, wherein the buffering surfactant is added during the neutralization step.

9. The process according to claim 1 or 2, wherein the buffering surfactant comprises an amine oxide surfactant.

10. The process according to claim 9, wherein the amine oxide surfactant is an alkyldimethylamine oxide surfactant.

11. The process according to claim 1 or 2, wherein the obtained concentrated surfactant blend has a pH of 7.3 to 9.5 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C.

12. The process according to claim 10, wherein the obtained concentrated surfactant blend has a pH of 7.3 to 9.5 when measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C.

13. The process according to claim 1 or 2, wherein the alkyl sulfuric acid and the buffering surfactant are combined in a weight ratio of 10:1 to 1:1 between the alkyl sulfuric acid and the buffering surfactant.

14. The process according to claim 1 or 2, wherein during or after the neutralization step, the neutralizing agent is added in a concentration that provides the resulting concentrated surfactant blend having a pH of 7.3 to 9.5, as measured as a 10% by weight solution of the concentrated surfactant blend in desalted water at 20°C.

15. The process according to claim 1 or 2, wherein the buffering surfactant is added at a concentration that provides the resulting concentrated surfactant blend having a preliminary alkalinity of 0.04 to 0.50 when measured as a 10% by weight solution of the concentrated surfactant blend in desalinated water at 20°C.

16. A concentrated surfactant blend obtained by the process described in claim 1 or 2.

17. a. 45% to 55% by weight of the concentrated surfactant blend, wherein the alkyl sulfated anionic surfactant has an average degree of alkoxylation of less than 0.5, a weight-average degree of branching of 15% to 50%, and a molar-average alkyl chain length of 12 to 13 carbon atoms. b. 10% to 15% by weight of a buffered surfactant, which is an amine oxide surfactant, in the concentrated surfactant blend. Includes, The concentrated surfactant blend according to claim 16, wherein the buffering surfactant is present at a concentration that provides the obtained concentrated surfactant blend having a preliminary alkalinity of 0.02 or greater when measured as a 10% by weight solution of the concentrated surfactant blend in desalinated water at 20°C, and the obtained 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 desalinated water at 20°C.

18. The concentrated surfactant blend according to claim 17, wherein the amine oxide surfactant is selected from the group consisting of C12-C14 alkyldimethylamine oxide, C12-14 alkylamidopropylamine oxide, and mixtures thereof.

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