Method for producing anhydrous sugar surfactant particles

Abstract

The present invention provides a novel process for the production of anhydrous sugar surfactant particles having a high bulk density, the process comprising drying an aqueous paste of alkyl and / or alkenyl polyglycosides having a solids content of 40%-60% by weight in a vacuum twin drum dryer to a residual water content of less than 2% by weight.

Description

Technical Field

[0001] This invention relates to a method for drying aqueous sugar surfactant pastes using a vacuum double-drum dryer. Background Technology

[0002] Due to growing ecological awareness in many areas (hereinafter, especially in the transportation industry), there is also a desire in the production of cosmetics and personal care products to produce concentrated solutions or anhydrous raw materials that can be immediately prepared with water before further processing.

[0003] Solid products that are packaged in bulk or on cardboard should especially avoid (plastic) packaging.

[0004] Sugar surfactants, such as alkyl polysaccharides (APGs – synonymous here with alkyl and / or alkenyl polysaccharides), are characterized by excellent detergent properties and high ecotoxicological compatibility. Characterizing good dermatological compatibility of these surfactants is particularly important in cosmetics. Other characteristics typically desired in the cosmetics, household, and personal care industries include sufficient water solubility, good compatibility with as many active ingredients and excipients as possible, good foaming ability, and good thickening properties. However, a fundamental requirement is that surfactants can be produced from biological sources, and especially from renewable raw materials. Surfactants that do not possess alkoxyl groups are desirable, thus eliminating the need for their production using ethylene oxide.

[0005] These advantages apply perfectly to alkyl polysaccharides. The latter are primarily used in liquid formulations, such as dishwashing liquids or shampoos, but there is also a growing market demand for solid, anhydrous forms that can be incorporated into, for example, powdered detergents or synthetic detergent soaps.

[0006] The drying of liquid surfactant formulations is typically carried out on an industrial scale by conventional spray drying, in which the aqueous surfactant paste is atomized as fine droplets at the top of a column while hot drying gas flows counter-currently. However, this technique is not readily applicable to sugar surfactant pastes. Spray drying of the product produces a viscous, non-flowable substance that largely adheres to the walls of the piping system and the cyclone separator walls of the spray dryer, eventually clogging the conduits and cyclone separators. Furthermore, the powder from such a method flows out of the dryer with difficulty due to its fineness and loses its flowability due to agglomeration when stored in the drum. However, especially in the case of alkyl polysaccharides, the drying temperature required is higher than the caramelization (i.e., decomposition) temperature of the sugar surfactant, and therefore conventional drying of sugar surfactant pastes yields a charred product. Agglomeration on the column walls (which requires expensive and inconvenient cleaning in short intervals) results in black, charred residues that are not only difficult to clean but also contaminate the resulting product with black particles due to abrasion.

[0007] DE 41 02 745 A1 discloses a spray drying method in which a fatty alcohol paste is mixed with a small amount of alkyl glucoside at 1% to 5% by weight, and the resulting mixture is subjected to conventional spray drying. This is possible only with the aid of small amounts of sugar surfactant and carrier material, as the method is only feasible in the presence of large amounts of inorganic salts. Higher concentrations of dried sugar surfactant can only be obtained through co-processing with auxiliaries, as described in German patent application DE 41 39 551 A1. This document discloses a spray drying method in the presence of a mixture of soda and zeolite, but provides a final product containing up to 50% by weight of sugar surfactant.

[0008] Finally, international patent application WO 95 / 14519 discloses a method of subjecting sugar surfactant pastes to superheated steam drying, but this is technically very complex.

[0009] German patent specification DE 19 534 371 C1 discloses a relatively uncomplicated method that allows for the production of high-quality, virtually anhydrous sugar surfactant powders or granules without the need for a common carrier during the drying process. This involves using a horizontal thin-film evaporator to dry alkyl polyglycosides and / or fatty acid N-alkyl polyhydroxyalkylamides, wherein a temperature gradient is applied from the product inlet to the product outlet, and the material to be dried is subjected to a countercurrent airflow. At the start of the drying operation, the material to be dried is subjected to a high level of thermal stress, which is unavoidable in this method. This method is also technically quite complex. The dryer employed is very expensive to produce because it requires a complex design and is more prone to failure during operation.

[0010] Therefore, the complex objective of this invention is to convert highly concentrated aqueous alkyl polysaccharide glycoside surfactant pastes into virtually anhydrous, highly concentrated, easily pulverized, dried products without the need for co-use of inorganic or organic carriers under low levels of thermal stress, while maintaining minimal technical complexity and relatively low energy consumption. The dried product should be characterized by acceptable color quality, good storage stability, good redispersibility, and performance characteristics comparable to those of prior art products. Summary of the Invention

[0011] This invention provides a method for producing anhydrous sugar surfactant particles, the method comprising, at a drum temperature of 100°C to 130°C, at a concentration of 3 to 7 kg / m³ 2 Aqueous pastes of alkyl and / or alkenyl polysaccharides, having a solids content of 40%-60% by weight and heated to at least 40°C, are dried in a vacuum twin-drum dryer with a specific drying capacity of / h.

[0012] The specific drying capacity of a concentrated alkyl polysaccharide solution (a) having a solid content of 40% to 60% by weight and having been heated to 40°C to 70°C can be achieved by the following

[0013] A temperature-controlled aqueous paste solution (a) is supplied to a vacuum twin-drum dryer at a constant rate, wherein the counter-rotating drums of the twin-drum dryer have a temperature of 100°C to 135°C and have been subjected to a vacuum of 5 to 25 mbar absolute pressure.

[0014] This provides a dried material with a residual water content as low as less than 2% by weight, which is easy to store, free-flowing and redispersible, and is not inferior to conventional products in terms of its performance characteristics.

[0015] This method can be run as both a batch method and a continuous method.

[0016] Surprisingly, it has been found that even using a relatively simple vacuum double-drum dryer, it is possible to produce a non-caking solid product of alkyl polysaccharides by drying without any product discoloration or agglomeration on the walls. The product passes through a temperature zone determined by the temperature of the drums. It has a short residence time within this zone, is cooled at the internal temperature of the dryer generated by the temperature of the drums and the outer shell after scraping the lower drum, and is further cooled after the dried material is removed from the dryer. In this drying method, the level of thermal stress on the product is significantly lower than that in prior art methods. Furthermore, the method consumes less energy in the absence of a temperature gradient with complex cooling. This method provides an easily pulverized final product with low residual moisture content.

[0017] "Low residual moisture" and the term "anhydrous" in this invention should be understood to mean a water content of up to 2%, preferably up to 1.5% and especially up to 1% by weight based on the dried product.

[0018] Foaming in the liquid bath supplied above the drums of a vacuum twin-drum dryer before and during the introduction of material into the drum gap often causes problems in the operation of the vacuum twin-drum dryer. This foaming prevents the formation of a closed, damp film on the drums, thus preventing interference with effective drying. This closed, damp film provides a uniformly dried product by removing water via temperature and vacuum.

[0019] Especially in the case of high-viscosity products, the bubbles formed in the foam can no longer escape, so the use of vacuum twin-drum dryers has been limited to drying low-viscosity fluids until now.

[0020] The method according to the invention unexpectedly makes it possible to convert pasty alkyl polysaccharides into a nearly anhydrous, highly concentrated, easily pulverized, flowable, and easily dispersed dried product using a robust, simply constructed vacuum twin-drum dryer, without high energy input. Depending on the dryer size, the method according to the invention can provide a dried solid form of APG in less than one minute from the initial contact with the drums. Therefore, the thermal stress on the material to be dried lasts only for a very short period, at a maximum of 130°C as determined by the drum temperature, and is thus significantly lower than in prior art methods. The low contact time results in a very gentle drying method on the product.

[0021] Vacuum double drum dryer (see) Figure 1 This is a sub-form of the vacuum contact dryer. It has a pair of rotating hollow drums whose surfaces are scraped by blades. When using a vacuum twin-drum dryer, the liquid bath is typically maintained in the space between the two rotating drums by supplying a solution. The supplied solution is brought to a temperature that ensures optimal viscosity before being applied to the drum gap between the rotating drums. In addition to this established temperature and viscosity of the supplied paste-like APG material, the drying of the thin layer on the drums or the evaporation of water is determined by the drum temperature of the dryer and the applied vacuum.

[0022] The method can be basically divided into three sub-regions: the supply of material to be dried, the drying of the material, and the removal / acquisition of the dried material.

[0023] (1) Supply of materials to be dried

[0024] Temperature and concentration of paste-like APG solution

[0025] Before supplying, the paste-like alkyl polysaccharide material is heated to a temperature of 40°C to 70°C, preferably 50°C to 55°C. The solids content of the APG-containing solution to be loaded onto the drum dryer should be between 40% and 60% by weight, particularly preferably 50% to 55% by weight. The solids content corresponds to the drying residue (determined via drying residue balance). In addition to pure APG, anhydrous alkyl polysaccharide materials contain byproducts (such as salts or polydextrose) as a result of production. A lower concentration solution of sugar surfactants can be dried. However, for higher throughputs, the drying operation becomes more efficient and the method more economical if the solids content of the supplied material is at least above 35% by weight. The upper limit of the solids content is a function of the processability of the material – in particular, its pumpability must be ensured.

[0026] Flow rate and specific drying capacity

[0027] The drums rotate in opposite directions, and a portion of the paste-to-liquid heated APG formulation is applied to the drum surface through the drum gaps, where it boils. During further rotation, a thin film of water evaporates into the steam extraction system, leaving a solid film that is scraped off the rotating drum surface with a sharp blade.

[0028] The conveying rate of the material to be dried must be matched with the size and rotational speed of the rollers, the gap width, and the vacuum power, as these parameters determine the picking up and taking out of the supplied material to be dried.

[0029] The rate can be calculated from the specific drying capacity. For the optimized method of the present invention, the specific drying capacity is 3 to 7 kg / m³. 2 / h, preferably 3.3 to 5.5 kg / m 2 / h and especially 3.5 to 4.5 kg / m 2 / h, where the unit should be understood as the number of kg of aqueous paste containing alkyl and / or alkenyl polysaccharides with a solid content of 40%-60% by weight that can be used per square meter of roller surface to be dried per hour.

[0030] Specific drying capacity is calculated per m³ 2 The drum area of ​​the dryer is reported, and is a specific value for the corresponding material to be dried based on the established process parameters.

[0031] Calculation of specific drying capacity

[0032] The condensation of the evaporated liquid during vacuum drying allows for a very accurate mass balance.

[0033] This includes determining the quality of the raw materials before drying: quality value 1 (pre-feed of raw materials) and after drying: quality value 2 (quality of the final dried product) to obtain the quality of the condensate by the difference from quality value 3.

[0034] During the entire drying process of a material with a mass value of 1, the stopping time and therefore the following are possible:

[0035] • Convert the evaporated (condensed) water volume into units per hour and per square meter based on time and drum area.

[0036] or

[0037] • Convert the dried final product into hours and square meters based on time and drum area.

[0038] Gap width

[0039] The gap width established between the two rollers determines the layer thickness of the material to be dried on these rollers.

[0040] This is essential for drying because water evaporation must occur between the application of the product to the rollers and the scraping off of the dried material—that is, within less than one roller rotation. The layer must be thin enough to ensure that the heat from the rollers can quickly reach both the bottom and top of the applied layer and be converted into evaporation energy. On the other hand, the layer cannot be too thin, as it must form a closed film to ensure uniform drying of the product, thereby avoiding energy loss and optimizing throughput and drying performance.

[0041] In the method of the present invention, the distance between the rollers is 0.05 mm to 5 mm, preferably 0.06 mm to 1.0 mm, particularly preferably 0.08 mm to 0.5 mm, and especially 0.1 mm to 0.3 mm.

[0042] (2) Drying

[0043] Pressure (absolute pressure, vacuum)

[0044] Vacuum contact dryers have the disadvantage that the material to be dried often begins to foam due to the applied vacuum. This depends on the composition of the product, but particularly on the viscosity of the solution to be dried. High-viscosity solutions produce more stable foam and release trapped bubbles only slowly, resulting in these bubbles remaining in the film or escaping only during application to the drums, thus leading to an irregular film. However, surprisingly, for high-viscosity paste-like alkyl polysaccharide solutions, it is possible to use a vacuum twin-drum dryer and produce a uniform film on the drums. Foaming can be reduced by establishing a lower vacuum. However, a higher vacuum helps to accelerate water evaporation and thus minimizes the temperature used for drying and the corresponding thermal stress on the material to be dried.

[0045] The method according to the invention is carried out at an absolute pressure of 5 to 30 mbar. If no intervention is made to the system, such as changing the feed of the product to be dried, removing the dried material, or briefly opening the closed drying system, an absolute pressure of 15 ± 5 mbar, particularly preferably 15 ± 3 mbar, is maintained.

[0046] Roller speed

[0047] The roller speed determines the residence time of the material to be dried from its application to the roller until the dried film is scraped off, and depends primarily on the selected roller temperature. Considering the heat load, the residence time should be as short as possible, but long enough to achieve the desired residual moisture. In the method according to the invention, the roller speed is 1 to 6 rpm, preferably 2 to 5 rpm, and particularly preferably 3 to 5 rpm.

[0048] Drum temperature

[0049] The selected drum temperature is the most critical parameter for successfully drying sugar surfactant solutions. In contact dryers, the applied drum temperature achieves direct drying by transferring heat to the applied material. Crucially, the heat introduced via the drum should only be used for water evaporation and should not lead to overheating of the material to be dried. Therefore, the drying of the material must be precisely completed at the moment the dried layer (“curtain”) is removed from the drum to avoid not only viscous products with excessive residual moisture (due to overly short drying) but also discoloration due to excessive thermal stress during excessively long drying periods. Foaming during feeding is surprisingly strongly dependent on the drum temperature, and higher drum temperatures are advantageous here.

[0050] The method according to the invention employs a drum temperature of 100°C to 135°C, preferably 105°C to 120°C, and particularly preferably 113°C ± 3°C.

[0051] Higher temperatures cause the material to harden, making uniform pulverization more expensive and complex. Further increases in temperature produce partially charred products.

[0052] The selected dryer's shell temperature has only a small effect on drying. Shell temperature control is used to prevent evaporated liquid from condensing on cooler components (inner surfaces - no air under vacuum), and therefore every vacuum drum dryer must have a shell heating element.

[0053] The shell temperature varies depending on the type of liquid. The surface temperature required for solutions is significantly lower than that for water-based liquids.

[0054] In the case of aqueous liquids, as is the case here, the shell temperature should be between 40°C and 80°C, preferably 50°C ± 5°C, to prevent water removed from the material to be dried from condensing on the cooler inner walls of the dryer.

[0055] The type of heating is independent of the product, and the housing can be equipped with electric heating, a double housing with water or oil, or a coil.

[0056] therefore, Figure 1 The vacuum drum dryer shown includes (identified as number 6) a double-layered outer shell filled with liquid or a single thick wall heated by applied heating coils (the attached figure does not show a cavity and should be understood as the wall thickness of the process chamber).

[0057] Therefore, the optimal parameters for the drying method are:

[0058] •Introduction temperature = 40°C-60°C (temperature of the APG material introduced into the interstitial space)

[0059] • Absolute pressure = 5-30 millibars

[0060] • Drum temperature = 100°C-135°C

[0061] • Roller clearance width = 0.05-5 mm

[0062] • Casing temperature = 40°C-80°C

[0063] • Drum speed = 1-6 rpm

[0064] Therefore, the present invention provides a

[0065] A method for drying particles used in the production of anhydrous sugar surfactants, the method comprising:

[0066] a) Heating a concentrated alkyl polysaccharide solution having a solids content of 40% to 60% by weight to 40°C-60°C, and

[0067] b) A temperature-controlled aqueous paste solution from a) is supplied to a twin-drum dryer at a constant rate, wherein the counter-rotating drums of the twin-drum dryer have a gap width of 0.05 to 5 mm and a temperature of 100°C to 135°C, and the outer shell temperature of the dryer is 40°C to 80°C.

[0068] c) and a vacuum with an absolute pressure of 5 to 25 millibars already applied.

[0069] The preferred method is one with the following process parameters:

[0070] • Introducing temperature = 50°C-55°C (temperature of the APG material introduced into the gap)

[0071] • Absolute pressure = 15 ± 5 millibars

[0072] • Drum temperature = 105°C-120°C

[0073] • Roller clearance width = 0.06-1.0 mm

[0074] • Casing temperature = 50°C ± 5°C

[0075] • Drum speed = 2-5 rpm

[0076] The method with the following process parameters is particularly preferred:

[0077] • Introducing temperature = 50°C-55°C (temperature of the APG material introduced into the gap)

[0078] • Absolute pressure = 15 ± 5 millibars

[0079] • Drum temperature = 105°C-120°C

[0080] • Roller clearance width = 0.08-0.5 mm

[0081] • Casing temperature = 50°C ± 5°C

[0082] • Drum speed = 3-5 rpm

[0083] The method with the following process parameters is given special preference:

[0084] • Introducing temperature = 50°C-55°C (temperature of the APG material introduced into the gap)

[0085] • Absolute pressure = 15 ± 3 millibars

[0086] • Drum temperature = 113°C ± 3°C

[0087] • Roller clearance width = 0.1-0.3 mm

[0088] • Casing temperature = 50°C ± 5°C

[0089] • Drum speed = 3-5 rpm

[0090] (3) Detachment of dried material and optional post-treatment

[0091] When separating the dried material from the drum, the temperature of the material to be dried should not be too high to prevent adhesion (compaction) of the release layer. The temperature of the scraped material is further reduced after it has been scraped off in the dryer chamber and removed from the dryer. The material is collected after scraping the drum. In continuous operation of the dryer, this occurs in batching within a double-door system or in containers inside the dryer. The dried material is removed and optionally ground to improve flowability at a residual moisture content of less than 2% by weight, preferably less than 1.5% by weight, and particularly preferably up to 1% by weight.

[0092] Flow modifiers such as silica may also be added. Other inert flow modifiers include silica in any desired form (including pyrolytic silica, precipitated silica, aluminum silicate, magnesium silicate, etc.), zeolite, bentonite, montmorillonite, and attapulgite, and mixtures thereof. Optionally, the weight of the added inert flow modifier relative to the total sugar surfactant composition is from about 0.2:100 to about 3:100, particularly preferably about 2:100.

[0093] Alkyl and / or alkenyl polysaccharides

[0094] Alkyl and alkenyl polysaccharides—sometimes referred to in the literature as alkyl and / or alkenyl oligosaccharides—are known nonionic surfactants conforming to formula (I).

[0095] R 1 O-[G] P (I)

[0096] Where R 1 The denoting radicals represent alkyl and / or alkenyl groups having 4 to 22 carbon atoms, G represents a glycosyl group having 5 or 6 carbon atoms, and p represents a number from 1 to 10. They are obtainable by relevant methods of preparative organic chemistry. As representative examples from a large body of literature, references are made here to EP-A1-0 301 298 and WO 90 / 03977.

[0097] Alkyl and / or alkenyl polysaccharides can be derived from aldoses or ketoses having 5 or 6 carbon atoms, preferably from glucose. Therefore, preferred alkyl and / or alkenyl polysaccharides are alkyl and / or alkenyl polysaccharides. The exponent p in general formula (I) specifies the degree of oligomerization (DP), i.e., the distribution of monosaccharides and polysaccharides, and is represented as a number between 1 and 10. While p in a given compound must always be an integer and it can be assumed in particular here that p = 1 to 6, the p value of a particular alkyl polysaccharide is determined analytically.

[0098] The calculated parameters are typically a fraction. Alkyl and / or alkenyl polysaccharides with an average degree of oligomerization (p) of 1.1 to 3.0 are preferred. From a performance perspective, alkyl and / or alkenyl polysaccharides with an oligomerization degree of less than 2, and particularly between 1.2 and 1.8, are preferred.

[0099] Alkyl or alkenyl R 1 It can be derived from primary alcohols having 6 to 18, preferably 8 to 14, carbon atoms. Typical examples include 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, palmitole alcohol, oleyl alcohol, isostearyl alcohol, and industrial mixtures thereof, such as those obtained, for example, in the hydrogenation of industrial fatty acid methyl esters or in the hydrogenation of aldehydes derived from Roelen oxosynthesis. Preferably, it is derived from primary alcohols having 6 to 18, preferably 8 to 14, carbon atoms. 8 / 18 - The chain length C of the alcohol mixture obtained from the distillation separation of coconut oil fatty alcohols in the preliminary test is... 8 / 10 Alkyl polyglucosides (DP = 1 to 3, preferably 1.2-1.8), preferably based on hardened C 12 / 14 The chain length of coconut oil alcohol is C 12 / 14 Alkyl polyglucosides (DP = 1 to 3, preferably 1.2-1.8) and industrial C 9 / 11 alkyl polyglucosides of α-oxo-ols (DP = 1 to 3), chain length C 12-18 Alkyl polyglucoside (DP = 1 to 3, preferably 1.2 to 1.8). Industrial applicability

[0100] The solid obtained by the method according to the invention can then be blended with other components of the powdered surfactant (e.g., turmeric powder for detergents). In the field of personal care products, the dried product can be directly incorporated into anhydrous soap products. These powders can also be readily incorporated into aqueous formulations. Alternatively, the dried product can be readily redispersed in water directly before incorporation into cleaning or cosmetic formulations, thus drying improves the transport of raw materials in terms of space requirements and energy input. In fact, no difference in performance characteristics has been observed when using these powders compared to aqueous starting pastes. In synthetic detergent soap formulations, the particles can also be readily incorporated with, for example, fatty acids, fatty acid salts, starch, polyethylene glycol, etc. Example

[0101] Experiment 1: Laboratory desiccator with a drying area of ​​0.22 m²

[0102] Initial testing for drying a sugar surfactant solution with a 53% solids content was conducted on a laboratory scale (drying area 0.22 m²) in a commercially available vacuum double-drum dryer from IPT Pergande GmbH (06369 Südliches-Anhalt, OT Weißandt Gölzau). 2 (This was done)

[0103] Input materials:

[0104] Plantacare 1200 UP (BASF) - INCI: Lauryl glucoside, with a dry residue of 53.0% by weight. 12 -C 16 A turbid, high-viscosity aqueous solution of fatty alcohol polyglycosides.

[0105] The material to be dried was preheated to 50°C and metered into the gap between the rotating drums via a valve-controlled gravity feed. A vacuum of 15 mbar absolute pressure was applied in the dryer. The drying behavior of the alkyl polysaccharide paste was tested at different input rates, drum speeds, and drum temperatures of 75°C or 120°C. The solid film was scraped off the drums by blades and collected. The resulting dried solid flakes could be readily pulverized into a flowable powder with a moisture content of up to 2.0% by weight and up to 1% by weight at higher drum temperatures.

[0106] Process parameters:

[0107]

[0108] Experiments 1.1 to 1.3 - Drum temperature 75°C

[0109] Experiments 1.1 and 1.2 - The drum temperature was 75°C.

[0110]

[0111]

[0112] Experiment 1.3 - Increased introduction rate and roller speed

[0113]

[0114] Experiments 1.4 to 1.6 - Drum temperature 120°C

[0115] Experiment 1.4

[0116]

[0117] Experiment 1.5:

[0118]

[0119] Experiment 1.6:

[0120]

[0121] ■ Experiments 1.1 to 1.6 show that, contrary to experience with conventional drying methods, the vacuum dual-drum dryer enables the thermal and continuous drying of highly concentrated viscous sugar surfactant solutions. Foaming during feeding is unexpectedly strongly dependent on drum temperature, and higher drum temperatures are advantageous here. Higher drum temperatures also allow for increased drum speeds, which in turn allows for a significant increase in the introduction rate (comparator V5 -> V9). 0.28 kg / h -> 0.48 kg / h).

[0122] Excellent results with high product throughput were achieved in experiments 1.4 to 1.6 by preheating the material to drum temperatures of 50°C and 120°C. At these drum temperatures, a residual moisture content of ≤1% by weight was achieved through appropriate parameter settings.

[0123] Experiment 2: Vacuum double-drum dryer with a drying area of ​​0.40 m²

[0124] To increase throughput, further experiments were conducted on drying sugar surfactant solutions with a solids content of 53% in a commercially available vacuum double-drum dryer from Yptpergand LLC (06369 South Anhart, Vézanne district, Gorzo). This vacuum double-drum dryer has a capacity of 0.40 m. 2 The drum area and the following dryer characteristics:

[0125] Dryer parameters

[0126]

[0127] Input materials:

[0128] Plantacare 1200 UP (BASF) - INCI: Lauryl glucoside, a turbid, high-viscosity aqueous solution of C12-C16 fatty alcohol polysaccharide with 53.0% by weight of dried residue.

[0129]

[0130] Experimental series 2.1, 2.2, 2.3 and 2.4 were conducted on a larger twin-drum dryer to determine the optimal pressure range.

[0131] The results showed a clear dependence between pressure level and the achieved drying performance.

[0132] Visual inspection revealed that under higher pressure (lower vacuum), the continuity of the uninterrupted product layer on the drum decreased, resulting in lower product wettability. This also led to lower drying performance.

[0133] Experiment on the residence time of the product - Effect of drum temperature and speed

[0134] Changing the drum speed has a significant impact on product quality; that is, prolonged exposure to thermal stress—determined by drum temperature and residence time—can cause the product to transform into a melt.

[0135]

[0136]

[0137] The first dried products (Experiments 2.5 and 2.6) contained a very hard, glassy material similar to a melt. This high hardness also resulted in a greater energy input required to grind the product. Reducing the drum temperature from 120°C to 112°C significantly improved the product quality.

[0138] No melt formation was observed in the first experimental series at 120°C because the higher speed (4.0 rpm instead of 3.0 rpm) in experiments 1.4 to 1.6 resulted in a shorter residence time of the material on the drum, approximately 14 s.

[0139]

[0140]

[0141]

[0142]

[0143]

[0144] Summary of results:

[0145]

[0146] After processing, the dried materials from experimental series 1 and 2 were mechanically post-treated by grinding to obtain uniform free-flowing powder.

[0147] To obtain a uniform powdery dried material, after cooling in a nitrogen atmosphere for 12 hours, the product is ground in strip or curtain form:

[0148] ■ Grinding is carried out in an EIRICH R02 enhanced mixer with a filling volume of 3 to 5 liters and a diameter of 235 mm. The mixer features two-stage speed control and counter-rotating motion between the agitator and the plate.

[0149] ■ The grinding time is 30 seconds in each case.

[0150] ■ Regardless of the product form (material curtain or product roll), the grinding quality of the dried product is excellent.

Claims

1. A method for producing anhydrous sugar surfactant granules, the method comprising, at a drum temperature of 100°C to 130°C, at a concentration of 3 to 7 kg / m³ 2 Aqueous pastes of alkyl and / or alkenyl polysaccharides, having a solids content of 40%-60% by weight and heated to at least 40°C, are dried in a vacuum twin-drum dryer with a specific drying capacity of / h.

2. The method according to claim 1, wherein, The dryer operates under a vacuum with an absolute pressure of 5 to 25 millibars.

3. The method according to claim 1 and / or 2, wherein, The roller has a gap width ranging from 0.05 mm to 5 mm.

4. The method according to at least one of claims 1 to 3, wherein, The roller speed is 1 to 6 revolutions per minute.

5. The method according to at least one of claims 1 to 4, wherein, The method includes using an alkyl polysaccharide having formula (I), R 1 O-[G] p (I) Where R 1 The denoting symbol represents an alkyl and / or alkenyl group having 4 to 22 carbon atoms, G represents a glycosyl group having 5 or 6 carbon atoms, and p represents a number from 1 to 10.

6. The method according to at least one of claims 1 to 5, wherein, The dual-drum dryer is used at drum temperatures ranging from 105°C to 120°C.

7. The method according to at least one of claims 1 to 6, wherein, The drying method is operated at an absolute pressure (vacuum) of 15 ± 5 mbar, preferably 15 ± 3 mbar.

8. The method according to at least one of claims 1 to 7, wherein, The dual-drum dryer is used at an outer shell temperature of 50°C ± 5°C.

9. The method according to at least one of claims 1 to 8, wherein, The twin-drum dryer is used at a drum speed of 1 to 6 rpm, preferably 2 to 5 rpm, and particularly preferably 3 to 5 rpm.

10. The method according to at least one of claims 1 to 9, wherein, The method is followed by the drying of the product obtained by grinding.

11. A sugar surfactant particle, produced by at least one of the preceding claims, wherein, The residual moisture content is less than 1.5% by weight, preferably less than 1.0% by weight.

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