Drying method

Abstract

The invention relates to a drying method, in particular a spray drying method, for producing a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid, and to a pourable mixture obtained therefrom. Alkyl polyglycosides and salts of iminodisuccinic acid are biodegradable, are well tolerated by humans and can be used in a large number of everyday products, for example detergents and dishwashing detergents, hand soaps and cosmetic products. The problem addressed by the invention described here is therefore that of providing a spray drying method by means of which a pourable mixture of alkyl polyglycosides and salts of iminodisuccinic acid can be produced. The method according to the invention achieves this by way of the following steps: providing a fluidised bed reactor, introducing alkyl polyglycosides and salts of iminodisuccinic acid into the fluidised bed reactor, wherein the proportion of alkyl polyglycosides is at least equal to the proportion of salts of iminodisuccinic acid, and drying and / or agglomerating the alkyl polyglycosides and salts of iminodisuccinic acid in the fluidised bed reactor at temperatures up to 150°C, preferably at 50°C.

Description

[0001] DESCRIPTION

[0002] The invention relates to a drying process, in particular a spray-drying process for producing a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid, and to the pourable mixture obtained therefrom.

[0003] The production of a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid is of interest because the two substances are biodegradable, well tolerated by humans and can be used in a variety of everyday products, such as detergents and dishwashing detergents, hand soaps and cosmetic products.

[0004] Sodium iminodisuccinate, a salt of iminodisuccinic acid, is a chelating agent widely used in the cosmetics industry and other fields. It has the ability to form multiple bonds with a single metal ion, allowing it to effectively neutralize metal ions that can compromise the stability and appearance of cosmetics. Used as a stabilizer, it protects formulations from degradation by metal ions in water, thus helping to preserve the color, texture, and efficacy of the products. Compared to other chelating agents, it is considered more environmentally friendly due to its biodegradability and, at appropriate concentrations, is generally considered safe for use in cosmetics. In addition to cosmetics, it is also used in other products such as detergents due to its chelating properties.

[0005] Alkyl polyglycosides offer several advantages when used as granules in the formulation of solid foam products. First, their handling and dosing are easier, which is crucial for maintaining formulation consistency. Furthermore, granules offer better stability and a longer shelf life than liquid forms, facilitating storage and transportation. Their incorporation into solid foam products improves the efficiency of the foam produced and reduces packaging waste and the environmental impact associated with the transportation of liquid raw materials. Furthermore, dense granules offer other advantages in an industrial context, such as reduced dust generation, which facilitates the cleaning of equipment and work areas, greater dosing accuracy for better quality control, and safer handling and storage, which contributes to a healthier working environment.In the cosmetics industry, many surfactants are used in solid form, such as sodium stearate, sodium cocoyl sulfate, sodium lauryl sulfate or sodium cococyl isethionate.

[0006] The growing interest in solid anhydrous cosmetics, especially foaming products certified according to the international COSMOS standard and with a high naturalness index, can be explained by several factors. These products reduce water consumption and require less packaging, thus addressing environmental concerns and the "zero-waste" trend. Furthermore, their higher concentration offers greater efficacy and better value for money. Anhydrous cosmetics also make it possible to eliminate preservatives from their formulations. These can cause skin sensitization or even trigger allergies. Preservatives are also responsible for imbalances in the skin microbiome and disruption of the dermis's protective barrier.

[0007] One of the problems so far is to find natural chemical compounds that make it possible to form granules or powders that can be used in solid, (anhydrous) cosmetic compositions.

[0008] From WO 2020 / 104231 A1, a process for producing a powder or granulate is already known, which comprises at least one chelating agent selected from the alkali metal salts of methylglycinediacetic acid (MGDA), glutamic acid diacetate (GLDA), and iminodisuccinic acid (IDS), and at least one enzyme in a weight ratio of 5:1 to 1,000:1. The powder or granulate contains at least 75% by weight of chelating agent (A), the process comprising the following steps:

[0009] (a) mixing the at least one chelating agent (A) and the at least one enzyme (B) in the presence of water, thereby forming a solution or slurry,

[0010] (b) removing most of the water by spray drying or spray granulation using a gas with an inlet temperature of at least 125°C.

[0011] However, WO 2020 / 104231 A1 discloses neither a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid nor a process for its preparation.

[0012] Furthermore, a multiphase cosmetic agent for hair and skin cleansing is already known from WO 2005 / 023975 A1. This agent can comprise alkyl polyglycosides and iminodisuccinic acid, but only in liquid form. Based on the previously described prior art, the object of the invention described here is to provide a drying process with which a pourable mixture of alkyl polyglycosides and salts of iminodisuccinic acid can be produced. This object is achieved by a process according to the features of the applicable claim 1 and by the independent product claim 12. Further advantageous embodiments can be found in the dependent claims.

[0013] The invention relates to a drying process for producing a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid. A salt of iminodisuccinic acid is preferably the sodium salt, tetrasodium inodisuccinate. A pourable mixture is understood here to be a bulk-like mixture, i.e., the mixture is a powdery, granular, or lumpy mixture, i.e., one in a pourable form. The drying process is, in particular, a spray-drying process.

[0014] The method according to the invention comprises the following steps:

[0015] - Provision of a fluidized bed reactor,

[0016] - introduction of alkyl polyglycosides and salts of iminodisuccinic acid into the fluidized bed reactor, wherein the proportion of alkyl polyglycosides is at least equal to the proportion of salts of iminodisuccinic acid, and

[0017] - Drying of the alkyl polyglycosides and salts of iminodisuccinic acid in a fluidized bed reactor at temperatures up to 150°C, preferably at 50°C.

[0018] The applicant has surprisingly discovered that low drying temperatures are required for optimal drying to obtain a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid. This is surprising because, as the temperature increases and the associated faster drying, smaller particles are usually obtained when the substances to be dried, preferably in liquid form, are introduced or sprayed into the fluidized bed reactor. However, this was not observed by the applicant when introducing alkyl polyglycosides and salts of iminodisuccinic acid. Rather, the applicant has discovered that larger particles are formed as the temperature increases.The applicant suspects that this is due to increased agglomeration during drying, which likely occurs due to the chemical properties of the alkyl polyglycosides. Therefore, unusually low temperatures of up to 150°C are necessary for optimal results. Drying or agglomeration particularly preferably takes place at a temperature of 50°C. This unexpected behavior is presumably due to the fact that the iminodisuccinic acid salts act as heat-stable fillers and prevent the caramelization process of the alkyl polyglycosides during the drying process, particularly the spray-drying process.

[0019] The advantages obtained by producing a pourable mixture of alkyl polyglycosides and salts of iminodisuccinic acid are, in particular, that the powdery, granular or lumpy mixture has better transport, storage and dosing properties than a comparable liquid mixture.

[0020] In a particularly advantageous embodiment of the process according to the invention, the proportion of alkyl polyglycosides is greater than the proportion of iminodisuccinic acid salts. The higher proportion of alkyl polyglycosides results in improved particle formation. It is assumed that this is due to micelle formation of the alkyl polyglycosides. Ratios of 7:3 to 9:1 have proven particularly advantageous. According to a further advantageous embodiment of the invention, the proportion of alkyl polyglycosides and iminodisuccinic acid salts is 8:2 and 4:1, respectively. This mixing ratio of the pourable mixture exhibits lower hygroscopic properties than other ratios.

[0021] Furthermore, in an advantageous embodiment of the drying process, the invention provides that the salts of iminodisuccinic acid are introduced into the fluidized-bed reactor in solid form, followed by the introduction of the alkyl polyglycosides in the liquid phase. Alternatively, it is also conceivable for the two components, i.e., the alkyl polyglycosides and the salts of iminodisuccinic acid, to be introduced in the liquid phase, preferably via an internally or externally mixing atomizing nozzle. Alternatively, the two components can also be introduced into the fluidized-bed reactor in a common liquid phase.Another alternative is to introduce the alkyl polyglycosides and the salts of iminodisuccinic acid in a common liquid phase and additionally alkyl polyglycosides in a separate liquid phase and / or salts of iminodisuccinic acid in a separate liquid phase.

[0022] In a further advantageous embodiment of the drying process, the separate liquid phases of the alkyl polyglycosides and the salts of iminodisuccinic acid and / or the combined liquid phase of the alkyl polyglycosides and the salts of iminodisuccinic acid are atomized separately. This separate atomization can be carried out at different times or locations via one or more nozzles. This depends on the type of fluidized bed reactor. If the fluidized bed reactor has spatially offset regions or zones with different temperature levels, the separate atomization can take place simultaneously but spatially offset. This results in a continuous granulation process. The fluidized bed reactor can be designed as a fluidized bed trough for this purpose. However, if the fluidized bed reactor is not equipped with such different temperature ranges, the separate atomization takes place at different times in a discontinuous process.In a further advantageous embodiment of the drying process, the fluidized bed reactor is operated with spatially offset zones, wherein these zones have different temperature levels. This is also referred to as a multi-zone process. The combined liquid phase of the alkyl polyglycosides and the iminodisuccinic acid salts is introduced into a first zone of this type, which has a first temperature level. The separate liquid phase of the iminodisuccinic acid salts is introduced into a second zone of the fluidized bed reactor, wherein this second zone has a second temperature level. The first temperature level may differ from the second temperature level. In these zones, the temperature can be adjusted so that the drying conditions are optimized for each zone.Alternatively or cumulatively, the separate liquid phase of the alkyl polyglycosides can be introduced into the second zone of the fluidized bed reactor, with the temperature range being adapted accordingly to the alkyl polyglycosides. Further zones with additional temperature levels can be located before and after the first zone, whereby the temperature levels can be different. Thanks to the zones with different temperature levels, granulation and coating, for example, can be carried out in a single process step. In this case, salts of iminodisuccinic acid, for example, are injected in the liquid phase as a coating reagent into the second zone, or, if further temperature ranges are available, into the last temperature zone. The process parameters must be adapted to the coating process.

[0023] In a further advantageous embodiment, a nucleating agent is introduced into the fluidized bed reaction. A nucleating agent is a compound that promotes or initiates crystallization. These compounds serve in particular to provide nucleation sites right at the beginning of the process, to promote crystal formation, to adjust and refine the size of the growing crystals, to prevent the forming particles from agglomerating and clumping, and to influence the rate of crystallization and the formation of specific crystal phases. Examples of nucleating agents are SiO2, Na2SO4, CaCO3, TiC, Al2O3, Fe2O3, Ba2SO4, and MgO. Also conceivable are microspheres made of materials such as SiO2, Al2O3 or polymers, particles of metal oxides, small amounts of impurities, or zeolites. SiO2 has the advantage that particles with a size range of several hundred to thousands of micrometers can be obtained.

[0024] The nucleating agent is particularly preferably pre-crystallized salts of iminodisuccinic acid and / or pre-crystallized alkyl polyglycosides. The proportion of the nucleating agent is preferably 1 to 10 wt.%, particularly preferably 1 to 5 wt.%, based on the total mass of the pourable mixture.

[0025] To further improve the stability and particle formation, the invention provides, in a further advantageous embodiment of the drying process, that a coating with a coating reagent is carried out during the drying process, with salts of iminodisuccinic acid preferably being used as the coating reagent. For this purpose, the fluidized-bed reactor can be operated at different temperature ranges. This enables a multi-zone process.

[0026] In order to prevent agglomeration or clumping of the pourable mixture after drying of the components of the pourable mixture, which were preferably previously present in the liquid phase, i.e. the alkyl polyglycosides and the salts of iminodisuccinic acid, the invention provides for the process in a further advantageous embodiment that the pourable mixture is cooled to room temperature.

[0027] A second aspect of the invention relates to a pourable mixture produced by the process according to the invention. Depending on the mixing ratio of the two components, i.e., the alkyl polyglycosides and the salts of iminodisuccinic acid, this mixture can be hygroscopic. The particles of the pourable mixture preferably have a particle size of 200 μm to 2000 μm.

[0028] In a particularly advantageous embodiment, the alkyl polyglycosides of the pourable mixture have an alkyl chain with 4 to 12 carbon atoms. This has the advantage that the pourable mixture is detergent, solubilizing, non-foaming and sequestered. “Detergent” refers to the property of separating and cleaning impurities. “Solubilizing” refers to the property of dissolving impurities and dirt or making them more soluble. The term “non-foaming” refers to the property of preventing the formation of foam. Finally, the term “sequestering” describes the property of a compound to form complexes with metal ions and thus reduce their availability in the solution. This prevents metal ions from reacting with other existing compounds.to form complexes, thereby improving the cleaning effect and stability of the pourable mixture and preventing deterioration of the physico-chemical properties of the pourable mixture.

[0029] In a further advantageous embodiment of the pourable mixture, the particles have a surface roughness between 7 and 9 pm. "Surface roughness" refers to the morphological property of the pourable mixture. It quantifies the distance between the peaks and valleys present on the surface of the particles. It refers to a characteristic depth of the grooves or irregularities that run through the surface of the particles. The surface roughness of the pourable mixture can be measured, for example, using a VK-X160K confocal 3D laser scanning microscope from Keyence. Furthermore, in an advantageous embodiment, the pourable mixture can have a wet dissolution time of between 245 and 255 seconds for a mass of 20 g of pourable mixture in 200 ml of water. "Dissolution" refers to the transition from the solid phase of the pourable mixture to the aqueous phase.As a non-limiting example, the wet dissolution time can be measured by adding 20 g of granules to 200 ml of water while stirring with a bar magnet at 21 °C.

[0030] In a particularly advantageous embodiment of the pourable mixture, the alkyl polyglycosides comprise a decyl glucoside. The decyl glucoside has a carbon chain of 10 carbon atoms. This imparts to the pourable mixture a detergency compatible with the use of the product on the skin or scalp, as well as foaming properties that are visually acceptable to the consumer.

[0031] In a further advantageous embodiment, the pourable mixture has a naturalness index of 1 for its ingredients. "Naturalness index" is an index according to ISO standard 16128 (Part 2), which numerically determines the degree of natural or organic origin, allowing individual raw materials and finished products to be easily compared. ISO standard 16128 enables an international definition of naturalness by establishing guidelines for natural and organic cosmetics and their ingredients. This standard provides a calculation model for determining the percentage of ingredients of natural origin and thus the naturalness index, or percentage of naturalness, of a cosmetic composition based on the raw materials that make up the composition.The calculation of the naturalness index of a cosmetic ingredient is usually prepared and communicated by the supplier of the raw material.

[0032] If the naturalness index is 0, then the composition or cosmetic ingredient is of purely synthetic origin. If the naturalness index is 1, then the composition or cosmetic ingredient is of purely natural origin.

[0033] The pourable mixture particularly preferably has a moisture absorption of 12% to 14% based on the total mass of the pourable mixture, in an atmosphere with 80% humidity and a temperature of 20°C. Moisture absorption is measured as a percentage of the initial moisture content. Moisture absorption reflects the hygroscopic nature of a powder or granulate, or the ability of a powder or granulate to bind and dissolve in water. In a broader sense, it indirectly indicates the rate of solubilization of compounds in a powder or granulate. For example, moisture absorption can be measured in an ICH110 climatic chamber from Memmert GmbH.

[0034] As a preferred embodiment, the pourable mixture has a water activity in the range of 0.20 to 0.24. The term "water activity" refers to the water vapor pressure of a gas atmosphere in equilibrium with the medium (here, the pourable mixture) divided by the saturation vapor pressure of this atmosphere at the same temperature. This represents the amount of free water available for biological reactions. Bacteria do not grow at a water activity below 0.7. Above a water activity of 0.7, the pourable mixture is rapidly changing, as conditions are favorable for the growth of bacteria, mold, and other microorganisms.With regard to the present invention, the pourable mixture can be stored for at least 18 months without risk of degradation by microorganisms, provided the pourable mixture is stored in an airtight environment. As an example, the water activity of a pourable mixture can be determined using an AQUALab 3 TE water activity counter from Decagon Devices. In a further advantageous embodiment of the pourable mixture, it has a flow function in the range of 63 to 73, in particular 68. The term "flow function", also referred to as ffc, refers to the flow function of a bulk material and is the ratio between the maximum principal stress, o1, that the bulk material can experience without changing its consolidation, and the maximum stress, f. c, which is supported by the bulk material on a free surface developed for this state of consolidation. It is calculated using the formula:

[0035] It is possible to classify the bulk solid according to FFC and qualify its flow behavior. A flow function of 10 or more is considered free. Preferably, the pourable mixture exhibits free flow. "Free flow" means that the particles can flow relatively easily and without significant resistance. The pourable mixture thus possesses easy mobility. The flow function can be determined, for example, using a Ring Shear Tester RST-XS.s from Dietmar Schulze®.

[0036] In a further advantageous embodiment of the pourable mixture, it has a specific surface area between 3 and 9 m 2 / kg. "Specific surface area" is a measure of the total surface area of ​​the particles per unit mass. For example, the specific surface area of ​​a pourable mixture can be measured using a Malvern Panalytical Mastersizer 3000 granulometer equipped with an air pressure dispersion module.

[0037] Preferably, the pourable mixture comprises:

[0038] - a bulk density in the range of 1.28 to 1.34 g / cm3, measured with a helium pycnometer, or - a tapped density of 700 to 715 kg / m3, in particular 712 kg / m3, the tapped density being measured with a Ring Shear Tester RST-XS.s from Dr. Dietmar Schulze GmbH ®.

[0039] "Bulk density" is the ratio of the mass of a quantity of a pourable mixture divided by the volume it occupies. "Tammed density" is the ratio of the mass of a quantity of a pourable mixture divided by the volume it occupies after a step of compacting / packing the pourable mixture. For example, density can be measured by using a container of known volume and filling it with the pourable mixture. Excess pourable mixture is removed to obtain a straight edge.

[0040] Particularly advantageously, the pourable mixture has an elemental composition comprising:

[0041] - 63.5 to 71.58% carbon;

[0042] - 22.51 to 28.35% oxygen;

[0043] - 5.18 to 7.72% sodium; and

[0044] - from 0 to 1.18% silicon, where the percentages are to be understood as mass relative to the total mass of the pourable mixture. The term "elemental composition" refers to the quantitative determination of the chemical elements composing the pourable mixture. Silicon may be present in the elemental composition of the pourable mixture if a nucleating agent (SiO2) has been introduced into the pourable mixture in an amount of less than 5% by weight to initiate crystallization. For example, the elemental composition of a granule population can be determined using energy-dispersive X-ray spectroscopy with a Zeiss Supra 55 VP microscope.

[0045] Finally, the invention provides for the use of the pourable mixture obtained from the process according to the invention for the production of detergents, soaps and / or cosmetic products.

[0046] The invention is explained in more detail below using some exemplary embodiments.

[0047] For the following examples, AC 2000 Coco Source (batch: 230515ACO4B; quantity: 1100 kg; solid content: 50.9 wt.%) and Baypure CX 100 (batch: CHASME2128; quantity: 250 kg; solid content: 34 wt.%) were used as starting materials.

[0048] Examples 1 to 3 were carried out in an AGT 400 fluidized-bed spray granulator. Example 4 was carried out in a GF25 fluidized-bed spray granulator. The systems are equipped with a fluidized-bed reactor, a filter house with PES filter cloth, a wet scrubber, a tumbler screen (200 pm / 1000 pm), a Retsch mill (750 pm), and a Verderflex Smart B40 peristaltic feed pump (10 mm).

[0049] Example 1 :

[0050] Preparation of a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid by applying alkyl polyglycosides to salts of iminodisuccinic acid in a ratio of 4:1

[0051] The spray drying described below was carried out under the process conditions listed below:

[0052] Baypure CX 100 was introduced into the system as a carrier at 20 wt.% based on the dry mass through a 500 μm sieve, resulting in a fluidized bed mass of approximately 6 mbar. The addition of 80 wt.% alkyl polyglycosides based on the dry mass was carried out at 47°C at a very slow feed rate of approximately 200 g / min. After two hours, unloading began (approximately 5 mbar), and a final product yield of 15.5 kg was achieved. The residual moisture content in the final product was 5.13%. The granules were stable and had good flowability. Microscopic analysis revealed almost transparent, round particles with a recognizable white core, see Figure 1 . In a further step, the discharged granules were sieved to 500–1000 μm. The coarse and fine fractions of the fluidized bed were continuously separated and recycled via a cyclone, in this case a Retsch mill, during spray drying.

[0053] Example 2: Preparation of a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid from a liquid mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid in a ratio of 4:1. The spray drying described below was carried out under the process conditions listed below:

[0054] A liquid batch of 20.0 kg (10.1 kg solid) AC 2000 with 7.3 kg (2.5 kg solid) Baypure CX 100 was formed, heated to 60°C, and sprayed into the fluidized bed reactor with moderate stirring. The spray granulation proceeded stably at low drying temperatures and with continuous recirculation of the coarse and fine fractions using a Retsch mill to stabilize the bed mass and increase the drying surface for granulation.

[0055] The finished granulate exhibited good flow properties, but was cooled to room temperature before filling into the final packaging to prevent agglomeration or blocking. A final product yield of 50.0 kg and a fine fraction of 22.0 kg were achieved. Figure 2 shows the microscopic analysis of the resulting particles. Example 3:

[0056] Preparation of a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid from a liquid mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid in a ratio of 9:1

[0057] The spray drying described below was carried out under the process conditions listed below:

[0058] A liquid batch of 20.0 kg (10.1 kg solid) AC 2000 with 3.24 kg (1.1 kg solid) Baypure CX 100 was formed, heated to 60°C, and sprayed into the fluidized bed reactor with moderate stirring. The spray granulation proceeded stably at low drying temperatures and with continuous recirculation of the coarse and fine fractions using a Retsch mill to stabilize the bed mass and increase the drying surface for granulation.

[0059] The ratio of 9:1 (based on dry matter) resulted in a very elastic, pourable mixture whose particle surface was very soft and prone to agglomeration effects in the fluidized bed and compaction in the final packaging, even at lower temperatures. A final product yield of 50.0 kg was achieved. Figure 3 shows the microscopic analysis of the resulting particles. Example 4:

[0060] Production of a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid by separate atomization of a liquid batch comprising alkyl polyglycosides and salts of iminodisuccinic acid in a ratio of 9:1 and a separately introduced / atomized solution of salts of iminodisuccinic acid in a multi-zone process.

[0061] The areas or zones 1 / 2 and 3 of the fluidized bed reactor have different temperatures.

[0062] The spray drying described below was carried out under the process conditions listed below: A liquid mixture of 20.0 kg (10.1 kg solid) AC 2000 and 3.24 kg (1.1 kg solid) Baypure CX 100 was formed, heated to 60°C, and sprayed into the front section of a horizontal fluidized bed reactor (chamber 1 / 2) with moderate stirring. The separately prepared solution of Baypure CX 100 (42% dry matter, 1.4 kg solid) was fed separately into the middle section of the fluidized bed reactor at a feed temperature of 60°C, thus combining co-granulation and coating in a multi-stage process to achieve a final granulate ratio of 4:1 APG:IDS. The spray granulation was stable at low drying temperatures and with continuous recirculation of the coarse and fine fractions to the front area of ​​the fluidized bed reactor (zone 1) by means of a Retsch mill to stabilize the bed mass and enlarge the drying surface for granulation.

[0063] The finished granules exhibited good flow properties, but were cooled to room temperature before filling into the final packaging to prevent agglomeration or blocking. A final product yield of 36.0 kg and a fine fraction of 12.0 kg were achieved. Figure 4 shows the microscopic analysis of the resulting particles.

[0064] All microscopic examinations show that the particles have a berry-like shape and structure.

[0065] Thus, a drying process for producing a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid is described above, which is biodegradable and well tolerated by humans and is easier to transport, store and dose than a liquid mixture.

Claims

CLAIMS 1 . A drying process for producing a pourable mixture comprising alkyl polyglycosides and salts of iminodisuccinic acid, comprising the following steps: - Provision of a fluidized bed reactor, - introduction of alkyl polyglycosides and salts of iminodisuccinic acid into the fluidized bed reactor, wherein the proportion of alkyl polyglycosides is at least equal to the proportion of salts of iminodisuccinic acid, and - Drying of the alkyl polyglycosides and salts of iminodisuccinic acid in a fluidized bed reactor at temperatures up to 150°C, preferably at 50°C.

2. Drying process according to claim 1, characterized in that the proportion of alkyl polyglycosides is greater than the proportion of the salts of iminodisuccinic acid.

3. Drying process according to claim 2, characterized in that the proportions of alkyl polyglycosides and the salts of iminodisuccinic acid are present in a ratio of 7:3 to 9:

1.

4. Drying process according to at least one of the preceding claims 1 to 3, characterized in that the salts of iminodisuccinic acid are introduced into the fluidized bed reactor in solid form, with the alkyl polyglycosides subsequently being introduced in liquid phase.

5. Drying process according to at least one of the preceding claims 1 to 3, characterized in that the alkyl polyglycosides and the salts of iminodisuccinic acid - each in a liquid phase or - in a common liquid phase or - in combinations of a common liquid phase of the alkyl polyglycosides and the salts of iminodisuccinic acid and a separate liquid phase of the alkyl polyglycosides and / or a separate liquid phase of the salts of iminodisuccinic acid are introduced into the fluidized bed reactor.

6. Drying process according to claim 5, characterized in that the separate liquid phases of the alkyl polyglycosides and the salts of iminodisuccinic acid and / or the common liquid phase of the alkyl polyglycosides and the salts of iminodisuccinic acid are sprayed separately.

7. Drying process according to claim 6, characterized in that the fluidized bed reactor is operated with spatially offset regions which have different temperature levels, that the common liquid phase of the alkyl polyglycosides and the salts of iminodisuccinic acid is introduced into a first such region and that the separate liquid phase of the alkyl polyglycosides and / or the separate liquid phase of the salts of iminodisuccinic acid into a second such area of ​​the fluidized bed reactor.

8. Drying process according to at least one of the preceding claims, characterized in that a nucleating agent is introduced into the fluidized bed reaction.

9. Drying process according to at least one of the preceding claims, characterized in that a coating with a coating reagent is carried out during drying, wherein salts of iminodisuccinic acid are preferably used as the coating reagent.

10. Drying process according to at least one of the preceding claims, characterized in that after drying the pourable mixture is cooled to room temperature. 11 . Drying process according to at least one of the preceding claims, characterized in that it is designed as a spray-drying process.

12. Pourable mixture obtained from a process according to one of the preceding claims 1 to 11.

13. Pourable mixture according to claim 12, characterized in that it is hygroscopic.

14. Pourable mixture according to claim 12 or 13, characterized in that the particles have a size between 200 pm and 2000 pm.

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