System and method for preparing a diluted aqueous stream comprising sodium laureth sulfate

Description

Field

[0001] The disclosure relates to an apparatus for preparing a diluted aqueous stream comprising sodium laureth sulfate; a system comprising the apparatus, a source of an aqueous fluid and a source of a concentrated aqueous feed stream comprising sodium laureth sulfate; a method for preparing the diluted aqueous stream, the diluted aqueous stream obtained thereof, and its use for the preparation of a personal composition.Background

[0002] A wide variety of cosmetic compositions e.g., personal care compositions are available to the consumers. Many of them are emulsions and are prepared by mixing different compounds, in order to provide compositions having satisfactory properties and benefits to the consumer. Formulation is a complex science, as it requires mixing the compounds at the right time, in the right order, under the right conditions, in order to obtain compositions having the expected structure, properties and benefits. The formulator should carefully choose the apparatus and the method, knowing that the compounds should be sequentially added under different conditions. Various methods are known. See for example the US patent 10,695,274 B2.

[0003] Emulsions are particularly obtained by mixing a cosmetically acceptable carrier e.g., water and / or polyols with at least one surfactant. The at least one surfactant may be selected from the group consisting of anionic surfactants, non-ionic surfactants, cationic surfactants and zwitterionic surfactants; preferably anionic surfactants.

[0004] Anionic surfactants such as sulfate anionic surfactants are conventionally used in personal care compositions e.g., shampoo and conditioning compositions. For example, sulfate anionic surfactants may be selected from the group consisting of sodium lauryl sulfate, sodium laureth sulfate, ammonium lauryl sulfate, ammonium laureth sulfate, triethylamine lauryl sulfate, triethylamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, monoethanolamine lauryl sulfate, monoethanolamine laureth sulfate, diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauric mono glyceride sodium sulfate, potassium lauryl sulfate, potassium laureth sulfate, ammonium cocoyl sulfate, sodium cocoyl sulfate, potassium cocoyl sulfate, monoethanolamine cocoyl sulfate, sodium tridecyl benzene sulfate and sodium dodecyl benzene sulfate.

[0005] Amongst the sulfate anionic surfactants mentioned above, sodium laureth sulfate is particularly suitable for incorporation into personal care compositions. Indeed, sodium laureth sulfate exhibits superior performance, particularly in terms of foaming, cleaning and emulsifying properties. In addition, sodium laureth sulfate is rather inexpensive versus alternative anionic surfactants.

[0006] Sodium laureth sulfate may be provided in the form of a material comprising sodium laureth sulfate at a concentration in the range of ≥ 60 to ≤ 80 wt.%, related to the total weight of the concentrated raw material. However, when preparing a personal care composition, the incorporation of a concentrated raw material of sodium laureth sulfate is very cumbersome. Sodium laureth sulfate is a compound, which exhibits a specific viscosity behaviour, and which is sometimes referred to as a "wormlike micelle-forming surfactant' or a "non-monotonic viscoelastic surfactant". When the concentration of sodium laureth sulfate is of < 28 wt.-% or less or > 60 wt.-% or more, the material comprising it has a viscosity, which is low enough for being processed. In contrast, when the concentration of sodium laureth sulfate is in the range of ≥ 28 to ≤ 60 wt.-%, the viscosity of the material comprising it dramatically increases up to levels, at which the material cannot be processed anymore. Consequently, it is not possible to merely use a concentrated raw material of sodium laureth sulfate by progressively diluting it in a formulation, as the formulation will reach at some point in time a concentration leading to an unprocessable viscosity.

[0007] In order to overcome the drawbacks associated with the dilution of a concentrated raw material of sodium laureth sulfate, it is usually prediluted, for example at a concentration in the range of ≤ 28 wt.-% or less, related to the total weight of the prediluted raw material. However, the predilution of the concentrated raw material also has its own drawbacks. It requires carrying out an additional predilution step and temporarily storing the diluted raw material. It also requires additional equipment and monitoring. In addition, the diluted raw material may degrade or get contaminated over time, and therefore requires adding preservatives to it.

[0008] It is known a system and method for diluting sodium laureth sulfate from a concentrated raw material (see the technical brochure from the company Silverson available online at: https: / / www.silverson.com / us / resource-library / application-reports / dilution-of-high-active-surfactants). However, even though the disclosed apparatus allows diluting a concentrated raw material of sodium laureth sulfate to some extent, the method thereof is not entirely satisfactory.

[0009] There is a need for improved apparatus and method for preparing a diluted aqueous stream comprising sodium laureth sulfate. There is also the need for a method, which does not require prediluting the concentrated raw material comprising sodium laureth sulfate. There is also the need for avoiding storing a prediluted raw material comprising sodium laureth sulfate. There is also the need for limiting the incorporation of additional compounds, such as preservatives.Summary

[0010] The inventors have shown that sodium laureth sulfate may be satisfactorily directly added to an aqueous fluid, without prior prediluting it. Indeed, the inventors have shown that such direct addition, without predilution and storage, was possible using an apparatus comprising a recircularization loop equipped with the appropriate devices, particularly a homogenizer, the arrangement of which is adapted in order to closely control the injection of the concentrated aqueous feed stream comprising sodium laureth sulfate into the aqueous fluid. This is achieved by equipping the recircularization loop and the feeding line for supplying the concentrated aqueous feed stream with separate pumps, as well as by directly injecting it into the homogenizer. This direct addition using a separate pump eases the manufacturing operations, allows using a compacter apparatus, allows closely controlling the injection of the concentrated aqueous feed stream, avoids implementing additional steps, avoids using additional equipment, reduces the risks of degradation and contamination associated with the storage of a prediluted material comprising sodium laureth sulfate.

[0011] Hence, in a first aspect, the disclosure relates to an apparatus for preparing a diluted aqueous stream comprising sodium laureth sulfate, the apparatus comprising: a reactor for holding an aqueous fluid; at least one recircularization loop for conveying the aqueous fluid as a recirculated aqueous stream from the reactor back to the reactor; wherein the recircularization loop comprises a first pump and a homogenizer; at least one first feeding line for supplying a concentrated aqueous feed stream comprising sodium laureth sulfate; wherein the first feeding line comprises a second pump and is directly, fluidly connected to the homogenizer.

[0012] In a preferred embodiment, the first pump and the second pump are lobe pumps.

[0013] In a preferred embodiment, the homogenizer is a rotor-stator homogenizer.

[0014] In a preferred embodiment, the recircularization loop further comprises a flow metering device, and / or the first feeding line further comprises a flow metering device.

[0015] In a second aspect, the presently claimed invention relates to a system for preparing a diluted aqueous stream comprising sodium laureth sulfate according to claim 1, the system comprising: a source of an aqueous fluid; a source of a concentrated aqueous feed stream comprising sodium laureth sulfate; and an apparatus for introducing the concentrated aqueous feed stream into the aqueous fluid, for obtaining the diluted aqueous stream comprising sodium laureth sulfate.

[0016] In a third aspect, the presently claimed invention relates to a method for preparing a diluted aqueous stream comprising sodium laureth sulfate according to claim 5, comprising at least the steps of: (A) providing an aqueous fluid in the reactor and conveying it as a recirculated aqueous stream from the reactor back to the reactor; (B) providing a concentrated aqueous feed stream comprising sodium laureth sulfate and directly introducing it into the homogenizer; wherein the steps (A) and (B) are repeated until a diluted aqueous stream comprising sodium laureth sulfate is obtained, wherein the ratio of the weight concentrations of sodium laureth sulfate between the concentrated aqueous stream and the diluted aqueous stream is in the range of ≥ 2.0:1.0 to ≤ 5.0:1.0, preferably ≥ 3.0:1.0 to ≤ 5.0:1.0, more preferably ≥ 4.0:1.0 to ≤ 5.0:1.0.

[0017] In a preferred embodiment, steps (A) and (B) are continuously repeated.

[0018] In a preferred embodiment, in step (A), the recirculated aqueous stream has a flow rate in the range of ≥ 200 to ≤ 500 kg / min, preferably of ≥ 220 to ≤ 440 kg / min, more preferably of ≥ 240 to ≤ 380 kg / min.

[0019] In a preferred embodiment, in step (B), the concentrated aqueous feed stream has a flow rate in the range of ≥ 20 to ≤ 100 kg / min, preferably in the range of ≥ 30 to ≤ 70 kg / min, more preferably in the range of ≥ 35 to ≤ 65 kg / min.

[0020] In a preferred embodiment, the concentrated aqueous feed stream comprises sodium laureth sulfate at a concentration in the range of ≥ 60 to ≤ 80 wt.%, preferably in the range of ≥ 65 to ≤ 75 wt.%, more preferably in the range of ≥ 68 to ≤ 72 wt.%, related to the total weight of the concentrated aqueous feed stream.

[0021] In a preferred embodiment, the diluted aqueous stream comprises sodium laureth sulfate at a concentration in the range of ≥ 0.1 to ≤ 28 wt.%, preferably in the range of ≥ 1 to ≤ 24 wt.%, more preferably in the range of ≥ 2 to ≤ 20 wt.%, related to the total weight of the diluted aqueous feed stream.

[0022] In a preferred embodiment, the concentrated aqueous feed stream has a temperature in the range of ambient temperature, preferably in the range of ≥ 15 to ≤ 30 °C, more preferably in the range of ≥ 18 to ≤ 25 °C.

[0023] In a preferred embodiment, the recirculated aqueous stream has a temperature in the range of ≥ 20 to ≤ 80 °C.

[0024] In a fourth aspect, the disclosure relates to a diluted aqueous stream comprising sodium laureth sulfate, which is obtained by the method as described herein above and below.

[0025] In a fifth aspect, the disclosure relates to the use of the diluted aqueous stream comprising sodium laureth sulfate as described herein above and below, or a diluted aqueous stream comprising sodium laureth sulfate, which is obtained by the method as described herein above or below, for the preparation of a personal care composition.Brief description of the figures

[0026] Figures 1 and 2 represent schematic diagrams of the apparatus as described above and below.Detailed description

[0027] Before the different aspects, it is to be understood that this invention is not limited to particular compositions and formulations described, since such compositions and formulation 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 presently claimed invention will be limited only by the appended claims.

[0028] If hereinafter a group is defined to comprise at least a certain number of embodiments, this is meant to also encompass a group which preferably consists of these embodiments only. Furthermore, the terms 'first', 'second', 'third' or 'a', 'b', 'c', etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the presently claimed invention described herein are capable of operation in other sequences than described or illustrated herein. In case the terms 'first', 'second', 'third' or '(A)', '(B)' and '(C)' or '(a)', '(b)', '(c)', '(d)', 'i', 'ii' etc. relate to steps of a method or use or assay there is no time or time interval coherence between the steps, that is, the steps may be carried out simultaneously or there may be time intervals of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in the application as set forth herein above or below.

[0029] Furthermore, the ranges defined throughout the specification include the end values as well, i.e., a range of 1 to 10 implies that both 1 and 10 are included in the range. For the avoidance of doubt, applicant shall be entitled to any equivalents according to applicable law.

[0030] In the following passages, different aspects are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. 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.

[0031] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the presently claimed invention. Thus, appearances of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment, but may refer to the same embodiment. Further, as used in the following, the terms "preferably", "more preferably", "even more preferably', "most preferably" and "in particular" or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way.

[0032] Furthermore, the particular features, structures or characteristics 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 presently claimed invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0033] Further, it shall be noted that the terms "at least one", "one or more" or similar expressions indicating that a feature or element may be present once or more than once typically will be used only once when introducing the respective feature or element. In the following, in most cases, when referring to the respective feature or element, the expressions "at least one" or "one or more" will not be repeated, non-withstanding the fact that the respective feature or element may be present once or more than once.

[0034] As used herein the term "hair" may be "living", i.e., on a living body, or may be "non-living", i.e., in a wig, hairpiece or other aggregation of non-living keratinous fibres. Mammalian, preferably human hair is preferred. However, wool, fur and other keratin fibres (keratin-containing fibres) are suitable substrates for the composition of the presently claimed invention.

[0035] By "substantially free of" is meant a composition comprising a compound in an amount of ≤ 0.1 wt.-% or less, preferably in an amount of ≤ 0.01 wt.-% or less, more preferably in an amount of 0 wt.-% (free of), related to the total weight of the composition.

[0036] By "personal care composition" is meant a composition, which is suitable for application to skin and hair, particularly to human skin and hair. For example, a personal care composition may be a shampoo and / or conditioning composition.

[0037] All percentages are by weight of the fluid to which it is referred, unless otherwise specified. Also ratios are weight ratios unless specifically stated otherwise.Apparatus for preparing a diluted aqueous stream comprising sodium laureth sulfate

[0038] In a first aspect, the disclosure relates to an apparatus 1, 2 for preparing a diluted aqueous stream comprising sodium laureth sulfate, the apparatus comprising: a reactor 10, 20 for holding an aqueous fluid; at least one recircularization loop 11, 21 for conveying the aqueous fluid as a recirculated aqueous stream from the reactor 10, 20 back to the reactor 10, 20; wherein the recircularization loop 11, 21 comprises a first pump 12, 22 and a homogenizer 13, 23; a first feeding line 14, 24 for supplying a concentrated aqueous feed stream comprising sodium laureth sulfate; wherein the first feeding line 14, 24 comprises a second pump 15, 25 and is directly, fluidly connected to the homogenizer 13, 23.

[0039] The terms "upstream" and "downstream" are provided in reference to the fluid circularization.

[0040] The apparatus 1, 2 comprises a reactor 10, 20.

[0041] The reactor 10, 20 may comprise at least one circumferential outer wall, delimitating an inner volume. The reactor may comprise one outer wall or two outer walls (so-called double-wall reactor / tank). The inner volume may be filled with the fluids, which are supplied to / obtained in it, when carrying out the methods described herein.

[0042] The reactor 10, 20 may be substantially cylindrical in shape and have a substantially circular cross-section. The reactor 10, 20 may be substantially oriented in a vertical position, such that the reactor 10, 20 comprises a substantially vertical longitudinal axis and a substantially horizontal circular cross-section. The terms "top" and "bottom" are provided in reference to a substantially cylindrical reactor, which is in a vertical position.

[0043] The reactor 10, 20 may have a volume in the range of ≥ 50 to ≤ 5,000 L.

[0044] The reactor 10, 20 may have any suitable alternative shape and dimensions.

[0045] The reactor 10, 20 may be an open reactor or a closed reactor, preferably the reactor 10, 20 is a closed reactor. If the reactor is an open reactor, it may be opened at the top end. If the reactor 10, 20 is a closed reactor, it may be closed at the top end with a suitable closing device, for example a lid. If the reactor 10, 20 is a closed reactor, the inner volume may be under a controlled atmosphere (separate from the surroundings) or alternatively may not be under a controlled atmosphere, preferably the inner volume is not under a controlled atmosphere.

[0046] The reactor 10, 20 comprises at least one inlet point 16, 19, 26, 29, preferably from one to eight inlet points, more preferably from one to five inlet points. The at least one inlet point may be located at the half top portion of the reactor 10, 20. An inlet point may be located at the open top end of the reactor, it may be an opening in the wall of the reactor or, if present, it may be an opening in the closing device. The aqueous fluid may be added into the reactor 10, 20 at the inlet point 16, 26.

[0047] The reactor 10, 20 comprises at least one outlet point 27, preferably from one to three outlet points, more preferably one or two outlet points. The at least one outlet point 27 may be located at the half bottom portion of the reactor 10, 20. An outlet point may be located at the bottom end of the reactor 10, 20. The diluted aqueous fluid may be discharged at the outlet point.

[0048] The apparatus 1, 2 comprises at least one recircularization loop 11, 21, preferably from one to three recircularization loops, more preferably one recircularization loop.

[0049] The recircularization loop 11, 21 coveys the aqueous liquid as a recirculated aqueous stream from the reactor 10, 20 back to the reactor 10, 20. The recircularization loop 11, 21 may comprise any suitable devices, which would be fluidly connected with each other, using any suitable connecting lines.

[0050] The recircularization loop 11, 21 comprises a first pump 12, 22. The first pump 12, 22 is located upstream the homogenizer 13, 23. Consequently, the reactor 10, 20 is fluidly connected to the first pump 12, 22, the first pump 12, 22 is fluidly connected to the homogenizer 13, 23, and the homogenizer 13, 23 is fluidly connected to the reactor 10, 20.

[0051] The first pump 12, 22 may be a lobe pump. It is advantageous to use a lobe pump, as it avoids generating a shearing stress, which may impair the obtained emulsion. In contrast, the first pump 12, 22 preferably is not a roller pump, a propeller pump or a centrifugal pump. These types of pumps may generate a shearing stress, which may impair the obtained emulsion.

[0052] The recircularization loop 11, 21 comprises a homogenizer 13, 23. The homogenizer 13, 23 may be a rotor-stator homogenizer. It is advantageous to use a homogenizer 13, 23, particularly a rotor-stator homogenizer, as it allows an efficient injection of the concentrated aqueous feed stream into the recirculated aqueous stream.

[0053] The recircularization loop 11, 21 may comprise a flow metering device 28. It is advantageous to use a flow metering device 28 for measuring the flow rate of the recirculated aqueous stream, thereby monitoring that the recircularization is efficiently implemented, and that the first pump 12, 22 appropriately works.

[0054] The apparatus 1, 2 comprises at least one first feeding line 14, 24. The first feeding line 14, 24 supplies the concentrated aqueous feed stream comprising sodium laureth sulfate.

[0055] The at least one first feeding line 14, 24 is directly, fluidly connected to the homogenizer 13, 23. In contrast, the at least one first feeding line 14, 24 is not directly, fluidly connected to any connection lines and / or devices located upstream or downstream the homogenizer 13, 23. It is advantageous to directly, fluidly connect the first feeding line 14, 24 to the homogenizer 13, 23, instead of another section of the recircularization loop 11, 21, as it improves the mixing of the concentrated aqueous feed stream with the recirculated aqueous stream (and therefore the dilution of sodium laureth sulfate into the aqueous fluid). It particularly avoids the generation of localized areas within the recirculated aqueous stream, wherein the concentration of sodium laureth sulfate may exceed of > 28 wt.-%, thereby increasing the risk of clogging the apparatus.

[0056] The at least one first feeding line 14, 24 comprises a second pump 15, 25. It is advantageous to equip the first feeding line 14, 24 with a pump 15, 25 being separate from the pump 12, 22 equipping the recircularization loop 11, 21. Indeed, this allows controlling the injection of the concentrated aqueous feed stream, in an independent manner from the recirculated aqueous stream, thereby imparting an appropriate pressure and flow rate to the concentrated aqueous feed stream.

[0057] The second pump 15, 25 may be a lobe pump. It is advantageous to use a lobe pump, as it avoids generating a shearing stress, which may impair the concentrated aqueous feed stream. In contrast, the second pump 15, 25 preferably is not a roller pump, a propeller pump or a centrifugal pump, as these types of pumps may generate a shearing stress, which may impair the concentrated aqueous feed stream.

[0058] The at least one first feeding line 14, 24 may comprise a flow metering device 42. It is advantageous to use a flow metering device 42 for measuring the flow rate of the concentrated aqueous feed stream, thereby monitoring that the injection of the concentrated aqueous feed stream is efficiently implemented, and that the second pump 15, 25 appropriately works.

[0059] The apparatus 1, 2 may also comprise at least one additional device. For example, the apparatus may additionally comprise at least one heat exchanger 30, at least one static mixer 31, at least one by-pass line, at least one heater 32, at least one stirring tool 33, at least one additional feeding line 34, at least one inlet point and at least one outlet point.

[0060] The apparatus 1, 2 may comprise a heat exchanger 30. The heat exchanger 30 may be a plate heat exchanger. The heat exchanger 30 may be located at any suitable position of the recircularization loop. For example, the heat exchanger 30 may be located downstream the first pump 12, 22 and upstream the homogenizer 13, 23. It is advantageous to use a heat exchanger 30, as it allows closely controlling the temperature of the recirculated aqueous stream into the recircularization loop 11, 21, and avoids any unwanted cooling, which may occur during the recircularization.

[0061] The apparatus 1, 2 may comprise a static mixer 31. The static mixer 31 may be located at any suitable position of the recircularization loop 11, 21. For example, the static mixer 31 may be located downstream the first pump 12, 22 and upstream the homogenizer 13, 23. It is advantageous to use a static mixer 31, as it avoids any phase dissociation to happen during the recircularization, which may lead to an inhomogeneous recirculated aqueous stream to be sent back to the reactor 10, 20.

[0062] In one example, if the recircularization loop 11 only comprises a first pump 12 and a homogenizer 13, the fluid e.g., the recirculated aqueous stream may circulate (from upstream to downstream), via the connecting lines, from the reactor 10 through the first pump 12, and the homogenizer 13, back to the reactor 10. In another example, if the recircularization loop comprises a first pump, a heat exchanger and a homogenizer, the fluid may circulate (from upstream to downstream), via the connecting lines, from the reactor through the first pump, the heat exchanger, and the homogenizer, back to the reactor. In another example, if the recircularization loop 21 comprises a first pump 22, a heat exchanger 30, a static mixer 31 and a homogenizer 23, the fluid may circulate (from upstream to downstream), via the connecting lines, from the reactor 20 through the first pump 22, the heat exchanger 30, the static mixer 31, and the homogenizer 23, back to the reactor 20. Alternatively, the fluid may circulate (from upstream to downstream), via the connecting lines, from the reactor through the first pump, the static mixer, the heat exchanger, and the homogenizer, back to the reactor.

[0063] The apparatus 1, 2 may comprise at least one by-pass line. A by-pass line is a line allowing by-passing at least one device. The by-pass line may be located at any suitable position of the recircularization loop 11, 21. In such case, the devices located upstream and downstream the by-passed device would be directly, fluidly connected to each other. The recircularization loop 11, 21 may comprise a line by-passing the at least one heat exchanger 30. The recircularization loop 11, 21 may comprise a line by-passing the at least one static mixer 31. The recircularization loop 11, 21 may comprise a line both by-passing the heat exchanger 30 and the static mixer 31. The recircularization loop 11, 21 may comprise a line by-passing the homogenizer 13, 23.

[0064] The apparatus may comprise at least one heater 32. The heater 32 may be located inside the inner volume of the reactor, or it may be located within the wall thickness of the reactor, or it may be located between the walls of the reactor (in case of a double-wall reactor), or it may be located outside the wall of the reactor. The heater 32 allows heating the fluid contained within the reactor 10, 20.

[0065] The apparatus may comprise a stirring tool 33, a drive motor 36 and optionally a shaft 35. The stirring tool 33 may be located inside the reactor 10, 20. The stirring tool 33 is associated with the drive motor 36 and the optional shaft 35. For example, the stirring tool 33 may be propeller stirring tool.

[0066] The apparatus 1, 2 may comprise at least one second feeding line 17, 34, 37, preferably from one to eight second feeding lines, more preferably from one to five second feeding lines. Each second feeding line 17, 34, 37 may be connected to the corresponding inlet point 16, 26 of the reactor 10, 20 or of the recircularization loop 11, 21. It is advantageous to provide an apparatus 1, 2 comprising more than one feeding line, as it allows feeding different compounds to the aqueous fluid from different lines. Particularly, using separate feeding lines facilitates the sequential addition of different compounds, as it avoids connecting the feeding line to different sources of compounds. It also avoids the cross-contamination of the different sources of compounds. It also avoids having to clean the feeding line between the feeding of different compounds. It is also advantageous providing various inlet points in the reactor and in the recircularization loop, as it allows feeding different compounds at different points of the apparatus 1, 2, and therefore select the most suited location for feeding a compound, depending on its properties and its compatibility with the aqueous fluid and other compounds. It eases the cleaning of the apparatus, as any cleaning fluid may be fed at various point of the flow path.

[0067] The apparatus 1, 2 may comprise at least one outlet line 18, 38. The outlet line 18, 38 allows discharging the diluted aqueous stream or the personal care composition obtained with the methods according to the presently claimed invention. The at least one outlet line may be directly connected to an outlet point of the reactor 27. The direct connection of the outlet line allows separating the fluid flow during the mixing steps (through the recircularization loop) and the fluid flow once the mixing is achieved (through the outlet line). Alternatively, the at least one outlet line 18, 38 may be branched on the recircularization loop 11, 21. Branching the outlet line 18, 38 on the recircularization loop 11, 21 is advantageous in that it allows deviating the fluid flow once the mixing is achieved.

[0068] The apparatus 1, 2 may comprise at least one storage tank. A storage tank may be connected to the at least one outlet line 18, 38. The storage tank may be permanently or temporarily connected to the at least one outlet line. After being prepared in the reactor 10, 20 and the recircularization loop 11, 21, the aqueous fluid - for example the personal care composition - may be stored in at least one storage tank. The aqueous fluid may be stored before being filled into a suitable packaging article, for example a bottle.

[0069] The apparatus 1, 2 may comprise valves 39, 40, 41 at any suitable locations.System for preparing a diluted aqueous stream comprising sodium laureth sulfate

[0070] In a second aspect, the presently claimed invention relates to a system for preparing a diluted aqueous stream comprising sodium laureth sulfate according to claim 1, the system comprising: a source of an aqueous fluid; a source of a concentrated aqueous feed stream comprising sodium laureth sulfate; and an apparatus 1, 2 for introducing the concentrated aqueous feed stream into the aqueous fluid, for obtaining a diluted aqueous stream comprising sodium laureth sulfate.

[0071] The apparatus 1, 2 may be associated with any suitable sources of compounds. Any suitable sourcing device may be used, including a tank, a syringe, a steam supply (for example for supplying water).

[0072] The source of the aqueous fluid is fluidly connected to the apparatus 1, 2, using any suitable connecting line.

[0073] In a preferred embodiment, the source of the aqueous fluid is fluidly connected to the reactor 10, 20, for example to one of the inlet points of the reactor 16, 26.

[0074] The aqueous fluid, which is sourced, comprises water and optionally at least one additional compound. For example, the recirculated aqueous stream may comprise water at a concentration of ≥ 70 wt.-%, more preferably of ≥ 80 wt.-%, even more preferably of ≥ 95 wt.-%, related to the total weight of the aqueous fluid.

[0075] In a preferred embodiment, the aqueous fluid, which is sourced, essentially consists of water (i.e., about 100 wt.-%). In another preferred embodiment, the aqueous fluid, which is sourced, comprises water and at least one additional compound. The aqueous fluid may comprise any suitable compound for incorporation into a personal care composition. Suitable compounds may be chosen from the group consisting of polyols, fatty substances, surfactants, direct dyes, lipids, conditioning agents, anti-dandruff agents, thickening and rheology-modifying agents, suspending agents, solubilizing agents, preservatives, antioxidants, UV-filters and / or sunscreens, perfume or fragrance, moisturizing and humecting agents.

[0076] The aqueous fluid, which is sourced, is substantially free of sodium laureth sulfate.

[0077] The source of the concentrated aqueous feed stream comprising sodium laureth sulfate is fluidly connected to the at least one first feeding line 14, 24.

[0078] In a preferred embodiment, the concentrated aqueous feed stream comprises sodium laureth sulfate at a concentration in the range of ≥ 60 to ≤ 80 wt.%, preferably in the range of ≥ 65 to ≤ 75 wt.%, more preferably in the range of ≥ 68 to ≤ 72 wt.%, related to the total weight of the concentrated aqueous feed stream.

[0079] Before being introduced into the recirculated aqueous stream as a concentrated aqueous feed stream, the concentrated raw material may be hold in a storage tank.

[0080] The concentrated aqueous feed stream comprises sodium laureth sulfate. The source of the concentrated aqueous feed stream may be a concentrated raw material comprising sodium laureth sulfate, such as those being commercially available.

[0081] Sodium laureth sulfate is also known as sodium lauryl ether sulfate (SLES). Both expressions are interchangeably used. Sodium laureth sulfate has the following chemical formula (I):         CH 3 (CH 2 ) 11 (OCH 2 CH 2 ) n OSO 3 Na     (I) wherein the indicia "n" corresponds to the number of ethoxyl groups and is in the range of ≥ 2 to ≤ 6, preferably n is 2.

[0082] In a preferred embodiment, sodium laureth sulfate is selected from the group consisting of sodium laureth-2 sulfate, sodium laureth-3 sulfate, and sodium laureth-5 sulfate. In a more preferred embodiment, sodium laureth sulfate is sodium laureth-2 sulfate.

[0083] Sodium laureth sulfate may be prepared by ethoxylation of dodecyl alcohol, which may be derived from palm kernel oil or coconut oil. The resulting ethoxylate may therefore be converted to a half ester of sulfuric acid, which may thus be neutralized by conversion to the sodium salt.Method for preparing a diluted aqueous stream comprising sodium laureth sulfate

[0084] In a third aspect, the presently claimed invention relates to a method for preparing a diluted aqueous stream comprising sodium laureth sulfate according to claim 5, comprising at least the steps of: (A) providing an aqueous fluid in the reactor 10, 20 and conveying it as a recirculated aqueous stream from the reactor 10, 20 back to the reactor 10, 20; (B) providing a concentrated aqueous feed stream comprising sodium laureth sulfate and directly introducing it into the homogenizer 13, 23; wherein the steps (A) and (B) are repeated until a diluted aqueous stream comprising sodium laureth sulfate is obtained, wherein the ratio of the weight concentrations of sodium laureth sulfate between the concentrated aqueous stream and the diluted aqueous stream is in the range of ≥ 2.0:1.0 to ≤ 5.0:1.0, preferably ≥ 3.0:1.0 to ≤ 5.0:1.0, more preferably ≥ 4.0:1.0 to ≤ 5.0:1.0.An aqueous fluid is provided in the reactor 10, 20.

[0085] The aqueous fluid is conveyed as a recirculated aqueous stream from the reactor 10, 20 back to the reactor 10, 20. The recircularization via the reactor 10, 20 is advantageous in that the concentrated aqueous feed stream is introduced into the recirculated aqueous stream, which is then hold in the reactor 10, 20. This avoids using an additional equipment for storing the diluted aqueous feed stream such as a separate storage tank, contrary to conventional methods for prediluting concentrated raw materials comprising sodium laureth sulfate.

[0086] Before introducing the concentrated aqueous feed stream, the recirculated aqueous stream comprises water and optionally at least one additional compound. For example, the recirculated aqueous stream may comprise water at a concentration of ≥ 70 wt.-%, more preferably of ≥ 80 wt.-%, even more preferably of ≥ 95 % wt.-%, related to the total weight of the aqueous fluid.

[0087] In a preferred embodiment, the recirculated aqueous stream, before introducing the concentrated aqueous feed stream, essentially consists of water (i.e., about 100 wt.-%). In another preferred embodiment, the recirculated aqueous stream, before introducing the concentrated aqueous feed stream, comprises water and at least one additional compound. The aqueous fluid may comprise any suitable compound for incorporation into a personal care composition, as described above.

[0088] In a preferred embodiment, in step (A), the recirculated aqueous stream has a flow rate in the range of ≥ 200 to ≤ 500 kg / min, preferably of ≥ 220 to ≤ 440 kg / min, more preferably of ≥ 240 to ≤ 380 kg / min.

[0089] In a preferred embodiment, in step (A), the recirculated aqueous stream has a pressure of less than ≤ 5×10 5< Pa, preferably in the range of ≥ 0.1×10 5< Pa to ≤ 5.10 5< Pa.

[0090] In a preferred embodiment, the recirculated aqueous stream has a temperature in the range of ≥ 20 to ≤ 80 °C. The recirculated aqueous stream may have a temperature in the range of ≥ 20 to ≤ 30 °C, or ≥ 30 to ≤ 40 °C, or ≥ 40 to ≤ 50 °C, or ≥ 50 to ≤ 60 °C, or ≥ 70 to ≤ 80 °C.A concentrated aqueous feed stream is provided.

[0091] In a preferred embodiment, the concentrated aqueous feed stream comprises sodium laureth sulfate at a concentration in the range of ≥ 60 to ≤ 80 wt.%, preferably in the range of ≥ 65 to ≤ 75 wt.%, more preferably in the range of ≥ 68 to ≤ 72 wt.%, related to the total weight of the concentrated aqueous feed stream.

[0092] In a preferred embodiment, in step (B), the concentrated aqueous feed stream has a flow rate in the range of ≥ 20 to ≤ 100 kg / min, preferably in the range of ≥ 30 to ≤ 70 kg / min, more preferably in the range of ≥ 35 to ≤ 65 kg / min. This flow rate is advantageous in that it allows introducing the concentrated aqueous feed stream into the recirculated aqueous stream at a rate, which eases the solubilisation of sodium laureth sulfate.

[0093] In a preferred embodiment, in step (B), the pressure of the concentrated aqueous feed stream is superior to the pressure of the recirculated aqueous stream, preferably wherein the pressure of the concentrated aqueous feed stream is at least 0.4×10 5< Pa higher than the pressure of the recirculated aqueous stream. This difference of pressure can advantageously be obtained, by providing an apparatus 1, 2 comprising two separated pumps 12, 22 and 15, 25, as described above.

[0094] In a preferred embodiment, the concentrated aqueous feed stream has a temperature in the range of ambient temperature, preferably in the range of ≥ 15 to ≤ 30 °C, more preferably in the range of ≥ 18 to ≤ 25 °C.

[0095] In a preferred embodiment, in step (B), the concentrated aqueous feed stream is introduced into the recirculated aqueous stream for a period in the range of ≥ 1min to ≤ 1h, preferably in the range of ≥ 2 to ≤ 45 min, more preferably in the range of ≥ 3 to ≤ 30 min.

[0096] The concentrated aqueous feed stream is directly introduced into the homogenizer 13, 23, preferably a roto-stator homogenizer. The use of a homogenizer 13, 23, preferably a rotor-stator homogenizer, is advantageous in that there is sufficient friction for ensuring that the sodium laureth sulfate is homogeneously diluted into the recirculated aqueous stream. The inventors have shown that directly introducing the concentrated aqueous feed stream into the homogenizer 13, 23, instead of another section of the recircularization loop 11, 21, improves the mixing of the concentrated aqueous feed stream with the recirculated aqueous stream, and avoids the generation of localized areas of very high viscosity.

[0097] The method allows obtaining a diluted aqueous stream comprising sodium laureth sulfate.

[0098] In a preferred embodiment, steps (A) and (B) are continuously repeated. The concentrated aqueous feed stream is therefore continuously introduced into the recirculated aqueous stream via the homogenizer 13, 23. The continuous introduction of the concentrated aqueous feed stream into the recirculated aqueous stream allows steadily increasing the concentration of sodium laureth sulfate in the recirculated aqueous stream from zero to the targeted final concentration. This is advantageous in that it allows keeping the recirculated aqueous stream under constant agitation, through the recircularization, thereby avoiding the generation of localized areas of very high viscosity.

[0099] In a preferred embodiment, the diluted aqueous stream comprises sodium laureth sulfate at a concentration in the range of ≥ 0.1 to ≤ 28 wt.%, preferably in the range of ≥ 1 to ≤ 24 wt.%, more preferably in the range of ≥ 2 to ≤ 20 wt.%, related to the total weight of the diluted aqueous feed stream.Diluted aqueous stream comprising sodium laureth sulfate

[0100] In a fourth aspect, the disclosure relates to a diluted aqueous stream comprising sodium laureth sulfate, which is obtained by the method as described above.

[0101] The diluted aqueous stream can be directly used as a premix component for preparing a personal care composition. In such case, additional compounds as described above may be added to the fluid in order to obtain a personal care composition having suitable structure, properties et benefits.Use of the diluted aqueous stream comprising sodium laureth sulfate

[0102] In a fifth aspect, the disclosure relates to the use of the diluted aqueous stream comprising sodium laureth sulfate as described above, or the use of a diluted aqueous stream comprising sodium laureth sulfate, which is obtained by the method as described above, for the preparation of a personal care composition.Advantages

[0103] The presently claimed invention offers one or more of the following advantages: Obtaining of a diluted aqueous material comprising sodium laureth sulfate, suitable for direct use in a personal care composition; No requirements of prediluting the concentrated raw material comprising sodium laureth sulfate and for temporarily storing it before used; No requirements for adding additional compounds to the diluted aqueous stream comprising sodium laureth sulfate, such as preservatives; Obtaining of a homogenous diluted aqueous stream comprising sodium laureth sulfate; Absence of clogging of the apparatus, particularly the feeding lines conveying the concentrated aqueous feed stream, the homogenizer and the connection lines of the recircularization loop. Examples

[0104] It is provided an apparatus 1, 2, which is configured as follows: The apparatus 1, 2 comprises a reactor 10, 20, which comprises one circumferential outer wall, delimitating an inner volume. The reactor 10, 20 is substantially cylindrical in shape, has a substantially circular cross-section and is oriented in a vertical position. The reactor 10, 20 is a closed reactor, which is closed at the top end by a lid. The reactor 10, 20 comprises from one to five inlet points 16, 26, which are located at the half top portion of the reactor 10, 20. One to five second feeding lines 17, 34 open to the corresponding inlet points 16, 26, for feeding the fluid with suitable compounds. The reactor 10, 20 also comprises one or two outlet points 27, which are located at the half bottom portion of the reactor 10, 20. A heater 32 is located inside the inner volume of the reactor 10, 20, for heating the fluid contained therein. A propeller stirring tool 33 is arranged in the inner volume of the reactor 10, 20, for stirring the fluid contained therein. The stirring tool 33 is driven by a drive motor 36, through a shaft 35.

[0105] The apparatus 1, 2 comprises a recircularization loop 11, 21, which comprises from upstream to downstream, a first lobe pump 12, 22, a plate heat exchanger 30, a static mixer 31 and a rotor-stator homogenizer 13, 23. The recircularization loop 11, 21 also comprises a flow metering device 28. Two adjacent devices are fluidly connected using a suitable connecting line. The recircularization loop 11, 21 is fluidly connected to the corresponding outlet point 27 of the reactor 10, 20 and opens to the corresponding inlet point 19, 29 of the reactor 10, 20. The recircularization loop 11, 21 allows generating a loop of the aqueous fluid - thereby forming a recirculated aqueous stream - from the reactor 10, 20 back to the reactor 10, 20, for improving the mixing of the aqueous fluid with various compounds, and for obtaining a formulation having a satisfactory structure and satisfactory properties.

[0106] The apparatus 1, 2 also comprises a first feeding line 14, 24, which comprises a second lobe pump 15, 25. The first feeding line 14, 24 is directly, fluidly connected to the roto-stator homogenizer 13, 23. The first feeding line 14, 24 also comprises a flow metering device 42.

[0107] The first feeding line 14, 24 is in fluid communication with the source of the concentrated aqueous feed stream, which comprises sodium laureth-2 sulfate (SLE2S) at a concentration in the range ≥ 68 to ≤ 72 wt.%, related to the total weight of the concentrated aqueous feed stream. The reactor 10, 20 is in fluid communication with the source of an aqueous fluid, which essentially consists of water (i.e., about 100 wt.-%).

[0108] The aqueous fluid, which is provided into the reactor 10, 20, is conveyed through the recircularization loop 11, 21 from the reactor 10, 20 back to the reactor 10, 20, using the first lobe pump 12, 22. This allows generating a constant flux of the aqueous fluid having a flow rate in the range of ≥ 240 to ≤ 380 kg / min and a pressure of in the range of ≥ 0.1×10 5< Pa to ≤ 5.10 5< Pa. Once the flux within the recircularization loop 11, 21 is stabilized, the concentrated aqueous feed stream is directly introduced into the homogenizer 13, 23, using the second lobe pump 15, 25. This allows generating a constant flux of the concentrated aqueous stream having a flow rate in the range of ≥ 35 to ≤ 65 kg / min and a pressure being at least 0.4×10 5< Pa higher than the pressure of the recirculated aqueous stream wherein it mixes it. The concentrated aqueous feed stream is continuously introduced into the recirculated aqueous stream for a period in the range of ≥ 3 to ≤ 30 min, till a diluted aqueous stream comprises sodium laureth sulfate at a concentration in the range of ≥ 2 to ≤ 20 wt.%, related to the total weight of the diluted aqueous feed stream, is obtained.

[0109] The diluted aqueous stream comprising sodium laureth sulfate is then used for preparing of a personal care composition.

Claims

1. A system for preparing a diluted aqueous stream comprising sodium laureth sulfate, the system comprising: - a source of an aqueous fluid; - a source of a concentrated aqueous feed stream comprising sodium laureth sulfate; - an apparatus (1, 2), for introducing the concentrated aqueous feed stream into the aqueous fluid, for obtaining the diluted aqueous stream comprising sodium laureth sulfate, wherein the apparatus comprises: - a reactor (10, 20) for holding an aqueous fluid; - at least one recircularization loop (11, 21) for conveying the aqueous fluid as a recirculated aqueous stream from the reactor (10, 20) back to the reactor (10, 20); wherein the recircularization loop (11, 21) comprises a first pump (12, 22) and a homogenizer (13, 23); - at least one first feeding line (14, 24) for supplying a concentrated aqueous feed stream comprising sodium laureth sulfate; wherein the first feeding line (14, 24) comprises a second pump (15, 25) and is directly, fluidly connected to the homogenizer (13, 23).

2. The system according to claim 1, wherein the first pump (12, 22) and the second pump (15, 25) are lobe pumps.

3. The system according to any preceding claims, wherein the homogenizer (13, 23) is a rotor-stator homogenizer.

4. The system according to any preceding claims, wherein the recircularization loop (11, 21) further comprises a flow metering device (28), and / or wherein the first feeding line (14, 24) further comprises a flow metering device (42).

5. A method for preparing a diluted aqueous stream comprising sodium laureth sulfate with the system according to any of the preceding claims, comprising at least the steps of: (A) providing an aqueous fluid in the reactor (10, 20) and conveying it as a recirculated aqueous stream from the reactor (10, 20) back to the reactor (10, 20); (B) providing a concentrated aqueous feed stream comprising sodium laureth sulfate and directly introducing it into the homogenizer (13, 23); wherein the steps (A) and (B) are repeated until a diluted aqueous stream comprising sodium laureth sulfate is obtained, wherein the ratio of the weight concentrations of sodium laureth sulfate between the concentrated aqueous stream and the diluted aqueous stream is in the range of ≥ 2.0:1.0 to ≤ 5.0:1.0, preferably ≥ 3.0:1.0 to ≤ 5.0:1.0, more preferably ≥ 4.0:1.0 to ≤ 5.0:1.0.

6. The method according to claim 5, wherein steps (A) and (B) are continuously repeated.

7. The method according to any claim 5 or 6, wherein, in step (A), the recirculated aqueous stream has a flow rate in the range of ≥ 200 to ≤ 500 kg / min, preferably of ≥ 220 to ≤ 440 kg / min, more preferably of ≥ 240 to ≤ 380 kg / min.

8. The method according to any claims 5 to 7, wherein, in step (B), the concentrated aqueous feed stream has a flow rate in the range of ≥ 20 to ≤ 100 kg / min, preferably in the range of ≥ 30 to ≤ 70 kg / min, more preferably in the range of ≥ 35 to ≤ 65 kg / min.

9. The method according to any claims 5 to 8, wherein the concentrated aqueous feed stream comprises sodium laureth sulfate at a concentration in the range of ≥ 60 to ≤ 80 wt.%, preferably in the range of ≥ 65 to ≤ 75 wt.%, more preferably in the range of ≥ 68 to ≤ 72 wt.%, related to the total weight of the concentrated aqueous feed stream.

10. The method according to any claims 5 to 9, wherein the diluted aqueous stream comprises sodium laureth sulfate at a concentration in the range of ≥ 0.1 to ≤ 28 wt.%, preferably in the range of ≥ 1 to ≤ 24 wt.%, more preferably in the range of ≥ 2 to ≤ 20 wt.%, related to the total weight of the diluted aqueous feed stream.

11. The method according to any claims 5 to 10, wherein the concentrated aqueous feed stream has a temperature in the range of ambient temperature, preferably in the range of ≥ 15 to ≤ 30 °C, more preferably in the range of ≥ 18 to ≤ 25 °C.

12. A method according to any claims 5 to 11, wherein the recirculated aqueous stream has a temperature in the range of ≥ 20 to ≤ 80 °C.