Liquid taurate surfactant mixtures

Abstract

The present invention relates to a taurate surfactant mixture comprising taurate surfactants, formulations comprising the taurate surfactant mixtures, and the use of the inventive taurate surfactant mixture in formulations, including in cosmetic, dermatological, pharmaceutical, personal care, home care, hygiene, or similar formulations.

Description

[0001] LIQUID TAURATE SURFACTANT MIXTURES

[0002] This application claims priority to U.S. Provisional Patent Application 63 / 632,391, filed on April 10, 2024, the whole content of which is hereby incorporated herein by reference in its entirety for all purposes.

[0003] The present invention relates to a taurate surfactant mixture comprising taurate surfactants, formulations comprising the taurate surfactant mixture, and the use of the inventive taurate surfactant mixture in formulations.

[0004] Liquid detergent, cleaning, and conditioning formulations, such as hand cleaners or sanitizers, shower or bath cleaners, and shampoos and conditioners are staple items of commerce in modem societies. Among other things, such formulations and products are used by consumers to remove soil from the hands, the body, nails, and hair. In many applications, it is desirable for such formulations and products to be mild (i.e., they must not be harsh or irritating to the skin), they must clean effectively, and they must possess pleasing aesthetic attributes or characteristics. One of the more important aesthetic attributes for personal and beauty cleaning formulations and products is the character of lather produced by the formulation or product during use, with lather of high volume and exceptional creaminess being particularly desirable in such formulations or products, especially for removing soil from skin, hair, and nails.

[0005] Taurates, a class of surfactants derived from the amino acid taurine, have gained significant attention in various industries due to their unique properties and diverse applications. In particular, in personal and home care products and formulations, taurates exhibit a wide range of beneficial characteristics that make them useful and valuable ingredients.

[0006] Taurates belong to the family of anionic surfactants. The chemical structure of taurates consists in most cases of a hydrophobic alkyl or alkylaryl chain attached to the amino group of taurine, resulting in an amphiphilic molecule. This structure imparts both hydrophilic and hydrophobic properties to taurates, making them effective surfactants with versatile applications. N-Lauroyl-N-methyltaurine, also known as lauroyl-A-methyltaurine or simply lauroyl taurine, is a specific taurate surfactant that is common in personal care products and formulations. This compound is characterized by its unique properties and versatile applications in various personal care products and formulations. Notably, taurate-based surfactants, like N-lauroyl-N-methyltaurine, are known for their mildness to skin and hair. In particular, taurate-based surfactants have gentle cleansing properties, making them suitable for use in products generally intended for all skin and hair types, including individuals with sensitive skin or delicate hair. Further, taurate-based surfactants have excellent foaming properties, which contribute to the formation of stable foam in personal care products and formulations, such as shampoos, conditioners, body and hand washes, and facial cleansers. The ability to dissolve oils and remove dirt particles makes taurate-based surfactants effective in cleansing applications, leaving skin and hair feeling clean and refreshed. Additionally, taurate-based surfactants are compatible with a wide range of other ingredients commonly used in personal care products and formulations, including other surfactants, thickeners and conditioning agents. Their versatility allows the formulation of complex mixtures tailored to specific performance requirements without compromising stability or efficacy. In addition to their cleansing properties, they can have conditioning effects that can help improve the overall feel and manageability of skin and hair. With respect to hair products and formulations, these conditioning properties contribute to improved softness, smoothness and shine, providing additional benefits beyond basic cleansing.

[0007] The Schotten-Baumann reaction is a well-known and highly useful means for acylating taurine compounds by reaction therewith of a carboxylic acid chloride in the presence of alkali.

[0008] In U.S. Pat. No. 2,987,526 directed to a process for preparing salt-free 7V-acyl taurines, the reaction is carried out in acetone, dioxane or methylethyl ketone containing up to 15% water at reflux, cooled to about 20 °C, diluted with water to dissolve NaCl and other water soluble impurities, and the precipitated product is filtered off and washed with water. This process involves relatively expensive solvents and other disadvantages, procedural and otherwise. Furthermore, while taurate-based surfactants, such as A-lauroyl-A-methyltaurine are generally known, and methods for making taurate-based surfactants are also generally known, such taurate-based surfactants have stability and optical issues. In particular, taurate-based surfactants, such as A-lauroyl-A-methyltaurine, suffer from phase separation even at room temperature. Additionally, taurate-based surfactants, such as A-lauroyl-A-methyltaurine, can be or can become optically opaque, especially at low temperatures (e.g., below 15°C). Notably, even after bringing the taurate-based surfactants back to room temperature (e.g., at 25°C) after being exposed to such low temperatures, the surfactants are not homogenous and can phase separate. This makes the handling, processing, and storage of taurate-based surfactants, such as N-lauroyl-N-methyltaurine, difficult to manage since not only can the surfactants have optical issues at minimally low temperatures, but even upon heating the surfactants, they can phase separate. Moreover, as noted above, even without being exposed to minimally low temperatures, the taurate-based surfactants are known to phase separate at room temperature.

[0009] Therefore, there remains a need to provide a surfactant mixture comprising a taurate surfactant that is stable and transparent at room temperature. In particular, there remains a need to provide a surfactant mixture comprising taurate surfactants that is transparent at room temperature and does not phase separate at room temperature, and after being exposed to lower temperatures and brought back to room temperature does not show signs of phase separation. There also remains a need to provide a surfactant mixture comprising taurate surfactants that is transparent and is freeze-thaw-stable. These surfactant mixtures are advantageously free from freeze-thaw-stabilizing additives.

[0010] DETAILED DESCRIPTION OF THE INVENTION

[0011] Before the taurate surfactant mixture comprising taurate surfactants of the present invention, as well as formulations comprising the taurate surfactant mixture and the uses thereof are described in detail, it is to be understood that this invention is not limited to specific process conditions described herein, since such conditions may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0012] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compound" means one compound or more than one compound.

[0013] The terms "containing", "contains" and "contained of' as used herein are synonymous with "including", "includes" or " comprising", "comprises", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or process steps. It will be appreciated that the terms “containing”, “contains”, "comprising", "comprises" and "comprised of as used herein comprise the terms "consisting of, "consisting essentially of ", "consists" and "consists of.

[0014] Throughout this application, the term "about" is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value.

[0015] As used herein, the terms “% by weight”, “wt.-%”, “wt%”, “weight percentage”, or “percentage by weight” are used interchangeably. The same applies to the terms “% by volume”, “vol.- %”, “vol. percentage”, or “percentage by volume”, or “% by mol”, “mol- %”, “mol percentage”, or “percentage by mol”.

[0016] As used herein, the term “formulation” preferably refers to the specific arrangement or combination of ingredients, components and additives in a product. It involves the process of designing and creating a mixture that achieves certain desired properties or functions. A formulation can be applied to various fields such as pharmaceuticals, cosmetics, home care, personal care, and more. In the context of dermatological products, a formulation involves the selection of active ingredients, excipients, preservatives and other additives to produce a stable, effective and safe product with desired properties such as texture, viscosity, stability and therapeutic efficacy. As used herein, the term “dermatological” refers to anything related to the diagnosis, treatment, and prevention of disorders and conditions affecting the skin, hair, nails, and mucous membranes.

[0017] As used herein, the term “dermatological formulation” refers preferably to a formulation specifically designed for application on the skin to address various dermatological concerns. These formulations often contain active ingredients such as moisturizers, emollients, vitamins, antioxidants, anti-inflammatories, or medications tailored to treat conditions like acne, eczema, psoriasis, aging signs, or sun damage. Dermatological formulations come in various forms such as creams, lotions, gels, ointments, serums, or foams, formulated to penetrate the skin efficiently and deliver therapeutic or cosmetic benefits.

[0018] As used herein, the term “pharmaceutical” refers preferably to a substance or product intended primarily for use in medicine to diagnose, treat or prevent disease or health conditions in humans or animals. Pharmaceuticals include a wide range of substances, including drugs, medicines, vaccines, biologies and various formulations designed to exert therapeutic effects on the body. These substances undergo rigorous research, development, testing and regulatory approval processes to ensure that safety, efficacy and quality standards are met before they are introduced into clinical practice or the marketplace.

[0019] The terms "cosmetic" and "cosmetic formulation," unless otherwise stated, shall mean any substance or preparation intended to be placed in contact with the various external parts of the human body, including the epidermis, hair system, nails, and lips. "Cosmetics" may be placed with the intended purpose of cleaning, perfuming, beautifying, changing appearance and / or correcting odors and / or protecting or keeping the contacted portions of the human body in good condition.

[0020] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0021] In the following passages, different alternatives, embodiments and variants of the invention are defined in more detail. Each alternative and embodiment so defined may be combined with any other alternative and embodiment, and this for each variant unless clearly indicated to the contrary or clearly incompatible when the value range of a same parameter is disjoined. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0022] Furthermore, the particular features, structures or characteristics described in present description may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and from different embodiments, as would be understood by those in the art.

[0023] In a first embodiment, the present invention relates to a taurate surfactant mixture comprising taurate surfactants, the taurate surfactants comprising: a) at least one / f-alkyltaurine group, preferably a C1-C14 V-alkyltaurine group, more preferably a / f-methyltaurine group, with b) a carbonyl group bound to at least one hydrocarbon group having a Ce or greater linear or branched alkyl chain, wherein the taurate surfactant mixture comprises less than 4 wt.-% of taurate surfactants having a hydrocarbon group having a Ci6 or greater alkyl chain and the carbonyl group.

[0024] As used herein, the term “alkyl” means a monovalent saturated or unsaturated group, preferably a saturated straight chain, saturated branched chain, or cyclic hydrocarbon radical, typically a monovalent saturated hydrocarbon radical. Preferably, the term “alkyl” means a monovalent saturated straight chain, saturated branched chain or cyclic hydrocarbon radical, typically a monovalent saturated (Cl - C22 or Ci - C22) hydrocarbon radical, such as for example, methyl, ethyl, n- propyl, iso-propyl, n-butyl, sec-butyl, t-butyl, pentyl, n-hexyl, cyclohexyl, and cyclooctyl, which may optionally be substituted on one or more of the carbon atoms of the radical. In one embodiment, an alkyl radical can substituted on one or more carbon atoms of the radical with hydroxy, alkoxy, amino, halo, carboxy, or phosphono, such as, for example, hydroxymethyl hydroxyethyl, methoxymethyl, ethoxymethyl, isopropoxyethyl, aminomethyl, chloromethyl or trichloromethyl.

[0025] In particular, at least one alkyl is selected from C6-C22, preferably C6-C18, more preferably C6-C14 chains. For example, the alkyl chain is selected from:

[0026] C6 alkyl chain, for example n-hexyl, 2-methyl-pentyl, 3-methyl-pentyl, 2,2- dimethyl-butyl, 2,3-dimethyl-butyl,

[0027] C7 alkyl chain, for example n-heptyl, 2-m ethylhexyl, 3 -methylhexyl, 2,2- dimethylpentyl, 2,3 -dimethylpentyl, 2,4-dimethylpentyl, 3, 3 -dimethylpentyl, 3- ethylpentyl, 2,2,3-trimethylbutyl,

[0028] C8 alkyl chain, for example n-octyl, 2-m ethylheptyl, 3 -methylheptyl, 4- methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3, 3 -dimethylhexyl, 3,4-dimethylhexyl, 3 -ethylhexyl, 2,2,3- trimethylpentyl, 2,2,4-trimethylpentyl, 2, 3, 3 -trimethylpentyl, 2,3,4- trimethylpentyl, 2-m ethyl-3 -ethylpentyl, 3 -methyl-3 -ethylpentyl, 2, 2,3,3- tetramethylbutyl,

[0029] C9 alkyl chain, for example n-nonyl, 2-Methyloctyl, 3 -methyloctyl, 4- methyloctyl, 2,2-dimethylheptyl, 2,3-dimethylheptyl, 2,4-dimethylheptyl, 2,5- dimethylheptyl, 2,6-dimethylheptyl, 3,3-dimethylheptyl, 3,4-Dimethylheptyl, 3,5-Dimethylheptyl, 4,4-Dimethylheptyl, 3 -ethylheptyl, 4-ethylheptyl, 2,2,3- trimethylhexyl, 2,2,4-trimethylhexyl, 2,2,5-trimethylhexyl, 2,3,3-trimethylhexyl, 2,3,4-trimethylhexyl, 2, 3, 5 -trimethylhexyl, 2,4,4-trimethylhexyl, 3,3,4- trimethylhexyl, 3 -ethyl-2 -methylhexyl, 4-ethyl-2 -methylhexyl, 3 -ethyl-3 - methylhexyl, 3 -ethyl-4-m ethylhexyl, 2,2,3,3-tetramethylpentyl, 2, 2,3,4- tetramethylpentyl, 2,2,4,4-tetramethylpentyl, 2,3,3,4-tetramethylpentyl, 3-ethyl- 2,2-dimethylpentyl, 3-ethyl-2,3-dimethylpentyl, 3 -ethyl-2, 4-dimethylpentyl, 3,3- diethylpentyl, C10-C22 alkyl chain, for example n-decyl, isodecyl, undecyl, isoundecyl, dodecyl, isododecyl, tridecyl, isotridecyl, tetradecyl, isoetradecyl, pentadecyl, isopentadecyl, hexadecyl, isohexadecyl, octadecyl, isooctadecyl, eicosyl, docosanyl.

[0030] Further, at least one alkyl, preferably the alkyl of the N-alkyltaurine group, is selected from C1-C22, preferably Cl -Cl 4, more preferably C1-C8, even more preferably C1-C5 groups or chains.

[0031] In certain embodiments, the taurate surfactant mixture comprising the taurate surfactants can have at least one alkyl selected from C1-C22, preferably Cl -Cl 4, more preferably C1-C8, even more preferably C1-C5 groups or chains, and another alkyl selected from C6-C22, preferably C6-C18, more preferably C6-C14 groups or chains. In further embodiments, the taurate surfactant mixtures comprises the taurate surfactants having a C1-C3 alkyl, preferably a methyl, bound to the aminoethanesulfonic acid moiety of the taurate surfactant (e.g., preferably N-methyltaurine) and a carbonyl group bound to a hydrocarbon group having a linear or branched C6-C22 alkyl, preferably a C6-C18 alkyl, more preferably C6- C14 alkyl group. In certain embodiments, the carbonyl group bound to the hydrocarbon group having a linear or branched C6-C22 alkyl is more preferably a saturated linear or branched C6-C22 alkyl, preferably a saturated linear or branched C6-C18 alkyl, more preferably a saturated linear or branched C6-C14 alkyl chain.

[0032] A “taurate” including taurate surfactant(s) according to the present invention means preferably a chemical compound derived from taurine, an organic amino acid that contains a sulfonic acid group (-SO3H) and an amino group (-NH2). Taurates can be produced by an acyl chloride route, which includes reacting taurines, such as a salt of A-methyltaurine, with an acyl chloride or mixtures of acyl chloride, such as a long-chain acyl chlorides (e.g., C6-C22, preferably C6- C18, more preferably C6-C14 alkyl chains), a base, such as sodium hydroxide or potassium hydroxide, resulting in the formation of the taurate surfactant in salt form. Alternatively, taurates can be produced by an acid route, which uses a fatty acid or mixture of fatty acids instead of the acyl chloride(s) (e.g., a fatty acid or fatty acids having C6-C22, preferably C6-C18, more preferably C6-C14 alkyl chains). The fatty acids are reacted with the taurines, such as a salt of A- methyltaurine, at elevated temperatures and then distilled or extracted to obtain the resulting taurate surfactant in salt form.

[0033] A “mixture” according to the present invention means preferably in terms of chemical composition, a combination of two or more substances that are physically intermingled but not chemically bonded. Each component in a mixture retains its individual chemical properties and can be separated from the mixture through physical means, such as filtration, distillation, extraction, or evaporation.

[0034] Mixtures can vary in composition and can exist in various phases, including, for example, liquid-liquid mixtures (e.g., oil and water). In the present invention, the terms “mixture” and “composition” are used synonymously.

[0035] In preferred embodiments, the taurate surfactant mixture comprises two or more taurate surfactants in accordance with the invention. Further, in additional preferred embodiments, the taurate surfactant mixture comprises two or more taurate surfactants each having C8-C14 alkyls in which the taurate surfactants are both present in amounts greater than 0.5 wt.-%, preferably greater than 1 wt.-%, more preferably greater than 2 wt.-%, and even more preferably greater than 3 wt.- %. In other embodiments, the taurate surfactant mixture comprises two or more taurate surfactants each having C8-C14 alkyls in which the taurate surfactants are present in the mixture greater than 96 wt.-%, more preferably greater than 97 wt.- %, most preferably greater than 98 wt.-%.

[0036] Preferably, in the inventive taurate surfactant mixture, the taurate surfactants comprising: al) at least one C1-C14 A-alkyltaurine group with bl) a carbonyl group bound to at least one hydrocarbon group having a linear or branched C6-C22 alkyl group, preferably a Ce-Cu alkyl group, wherein the taurate surfactant mixture comprises less than 4 wt.-% of taurate surfactants having a C16-C22 alkyl group, preferably a Cie-Cis alkyl group, and the carbonyl group.

[0037] Preferably, the taurate surfactant mixture comprises less than 3 wt.-%, more preferably less than 2 wt.-%, and most preferably less than 1 wt.-% of taurate surfactants having a Ci6 or greater alkyl group. In particular embodiments, the taurate surfactant mixture comprises less than 3 wt.-%, more preferably less than 2 wt.-%, and most preferably less than 1 wt.-% of taurate surfactants having a Ci6- C22 alkyl group, more preferably a Cie-Cis alkyl group.

[0038] Preferably, in the inventive taurate surfactant mixture, the taurate surfactant mixture is liquid at 25°C, more preferably between 15 and 70°C, under standard conditions. Standard (physical) conditions preferably refer to a set of predefined parameters used as a reference point for measuring and comparing physical properties or conducting experiments. These conditions are established to ensure consistency and reproducibility in scientific measurements and data analysis. Standard physical conditions typically include specific values for temperature, pressure, and sometimes humidity. The most commonly encountered standard physical conditions are often denoted as follows:

[0039] 1. Standard Temperature and Pressure (STP): o Temperature: 0°C (273.15 K) o Pressure: 1 atmosphere (atm) or 101.325 kilopascals (kPa).

[0040] Preferably, in the inventive taurate surfactant mixture greater than 96 wt.-% of the taurate surfactants have a hydrocarbon group having a Ce-Cw-alkyl group and a carbonyl group, more preferably greater than 97 wt.-% of the taurate surfactants have a hydrocarbon group having a Ce-Cw-alkyl group and a carbonyl group, most preferably greater than 98 wt.-% of the taurate surfactants have a hydrocarbon group having a Ce-Cw-alkyl group and a carbonyl group. Preferably, the Ce-Cu- alkyl group is n-hexyl, n-octyl, n-decyl, dodecyl, and tetradecyl.

[0041] The hydrocarbon group in the inventive taurate surfactant mixture is preferably derived from C6-C22, preferably Ce-Cis, acyl chlorides, fatty acids, or mixtures thereof. More preferably, the hydrocarbon group in the inventive taurate surfactant mixture is derived from 80 to 99 wt.-% Ce-Cu and 1 to 20 wt.-% C16-C22 acyl chlorides, fatty acids, or mixtures thereof.

[0042] Preferably, the inventive taurate surfactant mixture comprises at least 0.1 to 35 wt.-%, preferably at least 10 to 35 wt.-%, more preferably 25 to 30 wt.-%, of the taurate surfactants, based on the total weight of the mixture. Preferably, the surfactant mixture comprises less than 3 wt.-%, more preferably less than 2 wt.-%, most preferably less than 1 wt.-%, of taurate surfactants having a hydrocarbon group having a Ci6 or greater alkyl chain and the carbonyl group.

[0043] Preferably, the taurate surfactant mixture comprises: a) 15 to 35 wt.-%, more preferably 20 to 35 wt.-%, of at least one taurate surfactant of formula (I): wherein R1 is a Ce-Cw-alkyl group and R2 is a Ci-Ci4-alkyl group, preferably methyl, and b) 0.01 to 3 wt.-%, more preferably 0.01 to 1 wt.-%, of at least one taurate surfactant of formula (II): wherein R3 is a C15 or greater alkyl group, preferably a Cis-C22-alkyl group, more preferably a C15-C20 alkyl group, and R4 is a Ci-Ci4-alkyl group, preferably methyl, and M+is selected from the group consisting of Na+, K+, NH4+or mixtures thereof.

[0044] Preferably, in the inventive taurate surfactant mixture, the mixture is exposed to at least one freeze-thaw process, and wherein said mixture is free from freeze-thaw- stabilizing additives, and after the freeze-thaw process no phase separation occurs, more preferably the mixture is obtained by exposure to at least two freeze-thaw processes, and wherein said mixture is free from freeze-thaw-stabilizing additives, and after the freeze-thaw process no phase separation occur.

[0045] Surfactant mixtures, in particular taurate surfactant mixtures, which, like water- in-oil emulsions, comprise water-soluble components dispersed therein are known in the prior art. Such mixtures have found a wide variety of uses. When such mixtures are frozen, for example due to the change of temperature while being transported, and subsequently are then thawed for use, there is generally a problem of precipitation or gel formation and / or a loss of product quality. To overcome this problem in the past, the art has been forced to add inorganic salts to depress the freezing point of the mixtures, or to reduce the amount of surfactant in the system for a given surfactant level.

[0046] For the purposes of the present invention, “freeze-thaw-stable” applies to a mixture, in particular an aqueous dispersion or aqueous solution, that does not precipitate or coagulate after at least one freezing event and at least one thawing event. In the freezing event, the mixture rigidifies into a solid or semi-solid material: in the thawing event, the frozen aqueous dispersion is brought to the same temperature as before it was frozen. At this thawing temperature, the formerly solid or semi-solid material is back in the form of a mixture or an aqueous solution.

[0047] This step makes it also possible to produce freeze-thaw-stable mixtures that possess an appropriate degree of long-term stability. Moreover, a mixture that does not coagulate after at least one freeze-thaw process makes it possible to provide a formulation that likewise does not coagulate after a freeze-thaw process. Mixtures of this type can therefore be shipped to cold regions and also stored there without their properties suffering. This can lead to reduced costs, since there is no need for appropriate thermal transportation and temperature-regulated warehouses.

[0048] Preferably, the inventive mixture is liquid at 10°C and above, preferably at 12°C and above, more preferably at 14°C and above, under standard conditions. Standard (physical) conditions preferably refer to a set of predefined parameters used as a reference point for measuring and comparing physical properties or conducting experiments. These conditions are established to ensure consistency and reproducibility in scientific measurements and data analysis. Standard physical conditions typically include specific values for temperature, pressure, and sometimes humidity.

[0049] Preferably, the viscosity of inventive taurate surfactant mixture at between 10°C to 15°C is between 10 and 1000 cP under standard conditions. Standard (physical) conditions preferably refer to a set of predefined parameters used as a reference point for measuring and comparing physical properties or conducting experiments as mentioned above. The viscosity is measured using a Brookfield viscometer spindle LV#3 @ 20 rpm (25°C).

[0050] Preferably, the APHA max of inventive taurate surfactant mixture color is less than 350, more preferably less than 300. Color is measured using a BYK spectrophotometer.

[0051] The term “APHA max”, "colour of APHA max", or similar terms refers to a specification commonly used in industries such as chemical manufacturing, pharmaceuticals and food processing to indicate the maximum acceptable level of colour in a substance, typically a liquid. "APHA" stands for the American Public Health Association, which has established a standard method for measuring colour in liquids using a colour scale. The APHA colour scale ranges from 0 to 500, with higher numbers indicating darker or more intense colour. For example, when a substance is specified as having a "colour of 300 APHA max", this means that the colour of the substance should not exceed a value of 300 on the APHA colour scale. This limit ensures that the substance maintains an acceptable level of visual clarity and purity for its intended use. Substances meeting this specification are often used in applications where colour consistency and appearance are important factors, such as pharmaceutical formulations, chemical processes or food and beverage production.

[0052] Preferably, the taurate surfactant mixture is or is a part of a structured surfactant composition, an oil-in-water (O / W) emulsion, a water-in-oil (W / O) emulsion, or a transparent composition.

[0053] Oil-in-water (O / W) and water-in-oil (W / O) emulsions are two types of colloidal dispersions where one immiscible liquid (the dispersed phase) is dispersed as droplets within another immiscible liquid (the continuous phase). The stability and properties of these emulsions depend on various factors like the nature of the liquids, the presence of emulsifiers, and external conditions such as temperature and pressure. In an O / W emulsion, oil droplets are dispersed within a continuous phase of water. These emulsions are commonly used in various industries such as food, cosmetics, and pharmaceuticals. In a W / O emulsion, water droplets are dispersed within a continuous phase of oil. These emulsions find applications in industries such as cosmetics, where a moisturizing effect is desired. In both types of emulsions, emulsifiers play a crucial role in stabilizing the dispersed phase by reducing interfacial tension between the two immiscible liquids. Emulsifiers have hydrophilic and hydrophobic parts, allowing them to adsorb at the oil-water interface and prevent coalescence of droplets. The stability of these emulsions can be affected by factors such as temperature, pH, ionic strength, and the presence of other additives.

[0054] In certain embodiments, the inventive taurate surfactant mixture is or can be a part of a structured surfactant composition that is in the form of micellar phases.

[0055] Preferably, the inventive taurate surfactant mixture comprises: a) 15 to 35 wt.-% of at least one mixture of compounds of formula (III): wherein M+is selected from the group consisting of Na+, K+, NH or mixtures thereof,

[0056] R5 comprises linear or branched alkyl chains, wherein the alkyl chain distribution comprises: i) at least 4 % Cs-alkyl, more preferably at least 4 % to 12 % Cs-alkyl, ii) less than 3 % Ci6-alkyl, more preferably less than 1 % Ci6- alkyl, iii) less than 3 % Cis-alkyl, more preferably less than 1 % Cisalkyl, wherein any remaining alkyl chains comprise C9-alkyl to Cis-alkyl, preferably C- 10-alkyl to Cw-alkyl, and the alkyl chain distribution totals 100%. In preferred embodiments, the inventive taurate surfactant mixture comprises at least one mixture of compounds of formula (III) above, wherein the alkyl chain distribution of R5 comprises at least one other C9-alkyl to Cis-alkyl, preferably Cio-alkyl to Cw-alkyl, in addition to the Cs-alkyl and any Ci6-alkyl, any Cis-alkyl, or combinations thereof present in the taurate surfactant mixture.

[0057] Preferably, the inventive taurate surfactant mixture comprises: a) 0.1 to 35 wt.-% of at least one mixture of compounds of formula (IV): wherein M+is selected from the group consisting of Na+, K+, NH or mixtures thereof,

[0058] R6 comprises linear or branched alkyl chains, wherein the alkyl chain distribution comprises: iv) 4 to 15 % Cs-alkyl, preferably 4 to 12 % of Cs-alkyl, v) 50 to 96 % Cio-i4-alkyl, preferably 80 to 96 % of Cio-14- alkyl, more preferably 85 to 96 % of Cio-i4-alkyl, vi) less than 1.0 % Ci6-alkyl, vii) less than 1.0 % Cis-alkyl, wherein the total alkyl chain distribution totals 100%.

[0059] In another embodiment, the invention is directed to the use of the inventive taurate surfactant mixture for cosmetic, dermatological, pharmaceutical, personal care, hygiene, or similar formulations, as well as such formulations comprising the taurate surfactant mixture.

[0060] Preferably, the inventive taurate surfactant mixture can be used in personal care formulations including but not limited to shampoos, conditioners, body washes, facial cleansers, hand soaps and baby products. Its mildness, foaming ability and compatibility with other ingredients make it suitable for gentle yet effective cleansing in a variety of skin and hair care applications. It can also be used in cosmetic products such as make-up removers, facial scrubs and shaving creams. Its ability to remove impurities without causing irritation makes it suitable for facial cleansing and skin care applications.

[0061] Preferably, the inventive taurate surfactant mixture can be incorporated into household cleaning products such as dishwashing detergents, laundry detergents and multi-purpose cleaners. Its foaming and cleaning properties make it effective in removing grease, dirt and stains from a variety of surfaces while being gentle on skin and fabrics.

[0062] Overall, the inventive taurate surfactant mixture is preferably a versatile surfactant valued for its mildness, foaming ability, compatibility and potential conditioning effects. Its wide range of applications makes it a valuable ingredient in the formulation of personal care, cosmetic, household cleaning and industrial products.

[0063] FIGURES

[0064] Fig. 1 shows the results of viscosity measurements for a taurate surfactant mixture according to the invention in comparison to a commercially available taurate surfactant mixture.

[0065] Fig. 2 shows the phase behavior at different temperatures which are held for Ih. Example 1 does not show a complete precipitation at 10°C, while Comparative Example 5 shows a complete precipitation at 10°C.

[0066] Fig. 3 shows the comparison between Example 1 (right bottle) and Comparative Example 5 (left bottle). Example 1 and Comparative Example 5 were both exposed to at least one freeze-thaw process to determine the phase stability, in which the freeze-thaw process comprises:

[0067] (i) Starting at room temperature and then decreased the temperature down to 15°C, holding at 15°C overnight (around 19h) and then increasing the temperature back to room temperature;

[0068] (ii) Decreasing the temperature from room temperature down to 10°C, holding at 10°C overnight (around 19h) and then increasing the temperature back to room temperature;

[0069] (iii) Decreasing the temperature from room temperature to 5°C overnight (around 19h) and then increasing the temperature back to room temperature.

[0070] Example 1 is clear and no phase separation takes place.

[0071] EXAMPLES: Example 1 was prepared based on the following scheme:

[0072] R - C ocoyl e y au ne o um a

[0073] Procedure

[0074] • Begin with N-methyl taurine (NMT) and water at 48°C at a pH greater than 12.

[0075] • Introduce cocoyl chloride and sodium hydroxide to reactor over a three (3) hour period at a steady rate while maintaining the pH between 9 and 10.

[0076] • At the end of the three (3) hour period, additional sodium hydroxide is added to adjust the pH to a range of 7.0 to 8.5.

[0077] • Maintain at 48°C for 2.5 hours at a pH of 7.0 to 8.5.

[0078] • Recover the sodium methyl cocoyl taurate surfactant and desalinate the same.

[0079] Comparative Example 1 is a commercially available sodium lauroyl methyl taurate available from Syensqo.

[0080] Comparative Example 2 is a commercially available sodium methyl cocoyl taurate available from Syensqo.

[0081] Comparative Example 3 is another commercially available sodium methyl cocoyl taurate available from Syensqo that was desalinated.

[0082] Comparative Example 4 is also another commercially available sodium methyl cocoyl taurate available from Syensqo that was desalinated.

[0083] Comparative Example 5 is a commercially available sodium methyl cocoyl taurate sold under the brand LUXURIACT available from Innospec. Comparative Example 6 is a commercially available sodium methyl cocoyl taurate DIAPON™ K-SF available from NOF Corporation.

[0084] Table 1

[0085] As demonstrated in Table 1, the taurate surfactant mixture according to the invention (Example 1) is surprisingly and unexpectedly clear and homogenous at room temperature (RT). In comparison, other taurate surfactants that have a greater content of higher carbon alkyl chains (i.e., higher than C14, such as C16, C18, or both) are not stable at room temperature and, in fact, demonstrate phase separation at room temperature. Further, as demonstrated in Table 1, taurate surfactants that are not a mixture (i.e., that do not contain at least more than 0.5 wt. % of two or more taurate surfactants) likewise are not stable and phase separate at room temperature. See Comparative Example 1.

[0086] In addition, as shown in Fig. 2, Example 1 and Comparative Example 5 demonstrate significantly different phase behavior at low temperatures. Both Example 1 and Comparative Example 5 were cooled down from 25°C to 5°C and were held for one (1) hour at each temperature (i.e., one (1) hour at 25°C, one (1) hour at 15°C, one (1) hour at 10°C, and one (1) hour at 5°C).

[0087] Notably, as shown in Fig. 2, both Example 1 and Comparative Example 5 are opaque at 5°C, however, as shown in Fig. 3, upon returning to room temperature, Example 1 is clear and homogenous while Comparative Example 5 shows phase separation. Table 2

[0088] As shown in Table 2, Example 1 and Comparative Example 5 do not have the same carbon chain distribution and, in fact, Comparative Example 5 has more than 4 wt. % of taurate surfactants having a Ci6 or greater alkyl chain (along with a carbonyl group) as part of the hydrocarbon group. Specifically, Comparative Example 5 contains more than 4 wt. % of C 16 and C 18 alkyl chains. In this respect, not only does Comparative Example 5 show phase separation after returning to room temperature after being held at 5°C for one (1) hour, but precipitation is visible after thirteen (13) weeks at 45°C. In contrast, Example 1 is a clear and homogeneous mixture after returning to room temperature after being held at 5°C for one (1) hour, as well as after thirteen (13) weeks at 45°C. With respect to the viscosity measurements, the initial viscosity of Example 1 and Comparative Example 5 were measured at room temperature (25°C). Thereafter, Example 1 and Comparative Example 5 were cooled down in several cycles and then equilibrated to room temperature as follows:

[0089] (i) from room temperature to 20°C, holding at 20°C overnight (around 19h);

[0090] (ii) from room temperature to 15°C, holding at 15°C overnight (around 19h);

[0091] (iii) from 15°C to 10°C, holding at 10°C overnight (around 19h);

[0092] (iv) from 15°C to 5°C, holding at 5°C overnight (around 19h);

[0093] (v) equilibrating to room temperature.

[0094] After each cycle, the viscosity of the mixture was measured. The results are shown in Figure 1. Comparative Example 1 was solid (paste-like) at 5°C, so that no viscosity measurement could be done (Viscosity »30,000cP). After step (v), the optical appearance was assessed visually, then, the mixture was mixed for 5 minutes with a magnetic stir bar and the optical appearance was assessed visually again. The results are shown in Figure 2 and Table 2.

[0095] With respect to the viscosity measurement at 45°C in Table 2, the viscosity of Example 1 and Comparative Example 5 were measured for both after thirteen (13) weeks at 45°C.

[0096] As demonstrated in the tables and figures, taurates having a mixture of taurate surfactants with a particular carbon chain distribution have surprisingly and unexpectedly better stability (i.e., no phase separation) and optical properties (i.e., transparent), especially at ambient and lower temperatures. As mentioned above and shown in Table 1, the presence of more than 4 wt. % of taurate surfactants having C16 and C18 alkyl chains have worse stability after being exposed to lower temperatures and worse optical properties at lower temperatures.

Claims

Claims1. A taurate surfactant mixture comprising taurate surfactants, the taurate surfactants comprising: a) at least one C1-C14 N-alkyltaurine group with b) a carbonyl group bound to at least one hydrocarbon group having a Ce or greater linear or branched alkyl group, wherein the taurate surfactant mixture comprises less than 4 wt. % of taurate surfactants having a hydrocarbon group having a Ci6 or greater alkyl group and the carbonyl group.

2. The taurate surfactant mixture according to claim 1, the taurate surfactants comprising: al) at least one C1-C14 N-alkyltaurine group with bl) a carbonyl group bound to at least one hydrocarbon group having a linear or branched C6-C22 alkyl group, wherein the taurate surfactant mixture comprises less than 4 wt. % of taurate surfactants having a C16-C22 alkyl group and the carbonyl group.

3. The taurate surfactant mixture according to claim 1 or 2, wherein the taurate surfactant mixture is liquid at 25°C under standard conditions.

4. The taurate surfactant mixture according to any of the claims 1 to 3, wherein greater than 96 wt. % of the taurate surfactants have a hydrocarbon group having a Ce-Cw-alkyl group and a carbonyl group.

5. The taurate surfactant mixture according to any of the claims 1 to 4, wherein the hydrocarbon group is derived from C6-C22 acyl chlorides, fatty acids, or mixtures thereof.

6. The taurate surfactant mixture according to any of the claims 1 to 5, comprising at least 0.1 to 35 wt.-% of the taurate surfactants, based on the total weight of the mixture.

7. The taurate surfactant mixture according to any of the claims 1 to 6, wherein the taurate surfactant mixture comprises less than 3 wt. % of tauratesurfactants having a hydrocarbon group having a Ci6 or greater alkyl chain and the carbonyl group.

8. The taurate surfactant mixture according to any of the claims 1 to 7, comprising: a) 15 to 35 wt.-%, of at least one taurate surfactant of formula (I):wherein R1 is a Ce-Cw-alkyl group and R2 is a Ci-Ci4-alkyl group, and b) 0.01 to 3 wt.-%, of at least one taurate surfactant of formula (II):wherein R3 is a Cis-C22-alkyl group and R4 is a Ci-Ci4-alkyl group, and M+is selected from the group consisting of Na+, K+, NH4+or mixtures thereof.

9. The taurate surfactant mixture according to any of the claims 1 to 8, wherein the mixture is exposed to at least one freeze-thaw process, and wherein said mixture is free from freeze-thaw-stabilizing additives, and after the freezethaw process no phase separation occurs.

10. The taurate surfactant mixture according to any of the claims 1 to 9, wherein the mixture is liquid at 10°C and above under standard conditions.

11. The taurate surfactant mixture according to any of the claims 1 to 10, wherein the viscosity of the mixture between 10°C to 15°C is between 10 and 1000 cP under standard conditions.

12. The taurate surfactant mixture according to any of the claims 1 to 11, wherein the taurate surfactant mixture is or is a part of a structured surfactant composition, an oil-in-water (O / W) emulsion, a water-in-oil (W / O) emulsion, or a transparent composition.

13. The taurate surfactant mixture according to any of the claims 1 to 12, wherein the structured surfactant composition is in the form of lamellar phases.

14. The taurate surfactant mixture according to any of the claims 1 to 13 comprising: a) 15 to 35 wt.-% of at least one mixture of compounds of formula (III):wherein M+is selected from the group consisting of Na+, K+, NH or mixtures thereof,R5 comprises linear or branched alkyl chains, wherein the alkyl chain distribution comprises: i) at least 4 % Cs-alkyl, ii) less than 3 % Ci6-alkyl, iii) less than 3 % Cis-alkyl, wherein any remaining alkyl chains comprise C9-alkyl to Cis-alkyl and the alkyl chain distribution totals 100%.

15. The taurate surfactant mixture according to any of the claims 1 to 13 comprising: a) 0.1 to 35 wt.-% of at least one mixture of compounds of formula (IV):wherein M+is selected from the group consisting of Na+, K+, NH or mixtures thereof,R6 comprises linear or branched alkyl chains, wherein the alkyl chain distribution comprises:iv) 4 to 15 % Cs-alkyl, v) 50 to 96 % Cio-i4-alkyl, vi) less than 1.0 % Ci6-alkyl, vii) less than 1.0 % Cis-alkyl, wherein the total alkyl chain distribution totals 100%.

16. A formulation comprising the taurate surfactant mixture according to any of claims 1 to 15.

17. The formulation according to claim 16, wherein the formulation is a cosmetic, dermatological, pharmaceutical, personal care, hygiene, or similar formulation.

18. Use of the taurate surfactant mixture according to any of the claims 1 to 15 for cosmetic, dermatological, pharmaceutical, personal care, hygiene, or similar formulations.

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