Method for producing water-free sugar surfactant granules

Abstract

The invention relates to a new method for producing water-free high bulk density sugar surfactant granules. According to the method, aqueous pastes of alkyl- and / or alkenylpolyglycosides having a solids content of 40 - 60 wt.-% are dried in a vacuum double-drum dryer to a residual water content of below 2 wt.-%.

Description

[0001] Process for the production of anhydrous sugar surfactant granules

[0002] Field of the invention

[0003] The invention relates to a process for drying aqueous sugar surfactant pastes using a vacuum double roller dryer.

[0004] State of the art

[0005] Due to the growing ecological awareness in many areas, especially in the transport sector, the aim is also to offer concentrated solutions or water-free raw materials in the production of cosmetic and personal care products, which can be directly filled with water before further processing.

[0006] By using solid products that are packaged loose or in cardboard, the main aim is to avoid (plastic) packaging.

[0007] Sugar surfactants, such as alkyl polyglycosides (APG - here synonymous with alkyl and / or alkenyl polyglycosides), are characterized by excellent detergent properties and high ecotoxicological compatibility. The good dermatological compatibility that characterizes these surfactants is particularly required in cosmetics. Furthermore, in the cosmetics, home, and personal care sectors, sufficient water solubility, good compatibility with as many active ingredients and excipients as possible, good foaming ability, and good thickenability are generally desired. However, the need for surfactants that can be produced from biogenic sources and, in particular, renewable raw materials is essential. Surfactants that do not contain alkoxylated groups are desirable, thus eliminating the use of ethylene oxide in their production.

[0008] These advantages apply entirely to alkyl polyglycosides. They are predominantly used in liquid formulations such as dishwashing detergents or hair shampoos, but there is also a growing market demand for solid, water-free formulations that can be incorporated into powder detergents or synthetic soaps, for example.

[0009] The drying of liquid surfactant preparations is usually carried out on an industrial scale by conventional spray drying, in which the aqueous surfactant paste is sprayed at the top of a tower in the form of fine droplets, which are counteracted by hot drying gases. However, this technology is not readily applicable to sugar surfactant pastes. The product forms a sticky, non-flowing mass during spray drying, which largely adheres to the walls, in the tube systems and on the cyclone walls of the spray dryer and ultimately blocks the lines and cyclones. Furthermore, powder resulting from this type of process flows only poorly out of the dryer due to its fineness and loses its flowability when stored in drums due to caking. However, in the case of alkyl polyglycosides in particular, the temperatures required for drying are above the caramelization temperature, i.e.The decomposition temperature of sugar surfactants is so high that conventional drying of sugar surfactant pastes results in charred products. The buildup on the tower wall, which requires laborious cleaning at frequent intervals, leads to black, charred residues due to carbonization, which are not only difficult to clean but also contaminate the resulting product with black particles due to abrasion.

[0010] DE 41 02 745 A1 discloses a spray-drying process in which a small amount of 1 to 5 wt.% alkyl glucosides is added to fatty alcohol pastes and subjected to conventional spray-drying. This is only possible with low proportions of sugar surfactants and with the aid of carrier materials, since the process can only be carried out in the presence of a large amount of inorganic salts. Higher concentrations of dried sugar surfactants can only be obtained by processing them together with auxiliaries, as also described in German patent application DE 41 39 551 A1. This application presents a spray-drying process in the presence of mixtures of soda and zeolites, but in which end products containing a maximum of 50 wt.% of the sugar surfactant are obtained.

[0011] Finally, International Patent Application WO 95 / 14519 describes the drying of sugar surfactant pastes with superheated steam; however, this is technically very complex.

[0012] A less complex process that allows the production of high-quality, virtually anhydrous sugar surfactant powders or granules and does not require the use of carriers during the drying process is disclosed in German patent DE 19 534371 C1. This process uses a horizontal thin-film evaporator for drying alkyl polyglycosides and / or fatty acid N-alkyl polyhydroxyalkylamides. A temperature gradient is applied from the product inlet to the product outlet, and the material to be dried is flushed with air in countercurrent. At the beginning of the drying process, the material to be dried is subjected to high temperatures, which is unavoidable in this process. This process is also technically quite complex. The dryer used is very expensive to manufacture because it requires a complex design that is more prone to errors during operation.

[0013] Accordingly, the complex task of the present invention was to convert highly concentrated aqueous alkyl polyglycoside sugar surfactant pastes into virtually water-free, highly concentrated, easily comminuted drying products without the use of inorganic or organic carriers, under low temperature stress, with the least possible technical effort and lower energy consumption. The drying products should be characterized by acceptable color quality, good storage stability, good redispersibility, and comparable application properties to prior art products.

[0014] Description of the invention

[0015] The invention relates to a process for the production of anhydrous sugar surfactant granules, in which an aqueous paste of alkyl and / or alkenyl polyglycosides with a solids content of 40 - 60 wt.%, heated to at least 40°C, is dried in a vacuum double-roller dryer with a specific drying capacity of 3 to 7 kg / m 2 / h at a roller temperature of 100 to 130 °C.

[0016] The specific drying performance for the concentrated alkyl polyglycoside solution heated to 40 to 70 °C and having a solids content of 40 to 60 wt. (a) can be achieved by feeding the vacuum double-roller dryer at a continuous speed with the aqueous, tempered, pasty solution (a), the counter-rotating rollers of the double-roller dryer having a temperature of 100 to 135 °C and a vacuum of 5 to 25 mbar absolute pressure being applied.

[0017] In this way, a dried product is obtained with a residual water content of less than 2 wt.%, which is easy to store, free-flowing and redispersible, and which is not inferior to conventional products in terms of its application properties.

[0018] The process can be run as a batch process or as a continuous process.

[0019] Surprisingly, it was discovered that even with a technically less complex vacuum twin-roller dryer, non-caking solid products of alkyl polyglycosides can be produced by drying without product discoloration or caking on the walls. The product passes through a temperature zone determined by the temperature of the rollers. It has a short residence time there, cooling after the rollers scrape at the interior temperature of the dryer, which results from the roller and jacket temperatures, and further after the dried product is removed from the dryer. With this drying process, the temperature stress on the product is significantly lower than with state-of-the-art processes. Furthermore, the process is less energy-intensive, without the need to set a temperature gradient and require complex cooling. The result is an easily comminuted end product with a low residual moisture content.

[0020] Low residual moisture and in the present invention the term “anhydrous” means a water content of a maximum of 2 wt.%, preferably a maximum of 1.5 wt.% and in particular a maximum of 1 wt.% based on the dried product.

[0021] Foam formation in the feed liquid bath above the rollers of a vacuum double-roller dryer before and during the introduction of the product into the gap between the rollers often leads to problems when using vacuum double-roller dryers. This bubble formation prevents effective drying, as a continuous moist film is not formed on the rollers, which, through water removal through temperature and vacuum, produces a uniformly dried product.

[0022] Especially with products with high viscosity, air bubbles formed in the foam can no longer escape, so that the use of vacuum double roller dryers has so far only been used for drying low-viscosity fluids.

[0023] Surprisingly, the process according to the invention enables pasty alkyl polyglycosides to be converted into virtually water-free, highly concentrated, easily comminuted, free-flowing, and readily redispersible drying products using a robust, simply constructed vacuum twin-roller dryer without high energy consumption. Depending on the dryer size, the process according to the invention can provide a dry, solid form of APG in less than 1 minute from initial contact with the roller. The temperature load on the material to be dried is therefore only for a very short period of time at a maximum of 130°C, determined by the roller temperature, and is thus significantly lower than in prior art processes. The short contact time results in a very gentle drying process for the product. The vacuum twin-roller dryer (see Figure 1) is a subtype of the vacuum contact dryer.It features a pair of rotating hollow rollers whose surfaces are scraped by a knife. Typically, when using a vacuum double-roller dryer, a liquid bath is maintained in the space between the two rotating rollers by a feed system. The feed solution is heated to a temperature that ensures optimal viscosity before being applied to the nip between the rotating drums. In addition to the set temperature of the applied pasty APG mass and its viscosity, the drying or water evaporation process of the thin layer on the rollers is determined by the dryer's roller temperature and the applied vacuum.

[0024] The process can basically be divided into three parts: the feeding of the material to be dried, the drying of the material and the removal / recovery of the dried material.

[0025] (1) Feeding of the material to be dried

[0026] Temperature and concentration of the pasty APG solution

[0027] The pasty alkyl polyglycoside mass is heated to a temperature of 40°C to 70°C, preferably 50°C to 55°C, before feeding. The solids content of the APG-containing solution to be loaded onto the drum dryer should be between 40 and 60 wt. %, particularly preferably 50 to 55 wt. %. The solids content corresponds to the dry residue (determined by the dry residue balance). In addition to pure APG, the anhydrous alkyl polyglycoside mass contains by-products such as salts or polydextrose due to the production process. It is possible to dry lower-concentration solutions of the sugar surfactants. For higher throughput, however, the drying process is more effective and the method more economical if the solids content of the feed material is at least above 35 wt. %. The upper limit of the solids content is determined by the processability of the mass – in particular, the pumpability, which must be present.

[0028] Flow rate and specific drying capacity

[0029] The rollers rotate in opposite directions, and a portion of the pasty, liquid, heated APG preparation is applied to the roller surface via the roller gap, where it boils. As rotation continues, the thin film of water evaporates into the steam vent, leaving a solid film behind, which is scraped off the rotating roller surfaces by sharp knives. The feed rate of the material to be dried must be coordinated with the size and rotation speed of the rollers, the gap width, and the vacuum capacity, as these parameters determine the collection and removal of the material to be dried.

[0030] It can be calculated from the specific drying capacity. For the optimized process of the present invention, the specific drying capacity is 3 to 7 kg / m 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 is to be read as kg of the aqueous paste of alkyl and / or alkenyl polyglycosides to be dried with a solids content of 40 - 60 wt.% per square meter of the roller area available for drying per hour.

[0031] The specific drying capacity is given per m 2 Roller area of ​​the dryer and is a specific value for the corresponding drying material depending on the set process parameters.

[0032] Calculation of the specific drying capacity

[0033] By condensing the evaporated liquid during drying in a vacuum, a very accurate mass balance can be determined.

[0034] The mass of the raw material is determined before drying: mass value 1 (pre-dosage of the raw material), and after drying: mass value 2 (mass of the dried final product). By calculating the difference, mass value 3, the mass of condensed water, is obtained. Time was recorded throughout the drying process of the product that yielded mass value 1, and thus it is possible to either:

[0035] • to convert the evaporated (condensed) water as a function of time and roller area to one hour and one square meter or

[0036] • Convert the dried end product to one hour and one square meter depending on the time and the roller area

[0037] Gap width

[0038] The set gap width between the double rollers determines the layer thickness of the material to be dried on the rollers.

[0039] This is essential for drying, as the water evaporates from the moment the product is applied to the rollers until the dried product is scraped off, i.e., in less than one roller revolution. The layer must be sufficiently thin so that the temperature of the rollers quickly reaches the applied layer on both the bottom and top sides and can be converted into evaporation energy. On the other hand, the layer must not be too thin, as it must form a continuous film to ensure even drying of the product, avoid energy losses, and optimize throughput and drying performance.

[0040] In the present process, the distance between the rollers is 0.05 to 5 mm, preferably 0.06 to 1.0 mm, particularly preferably 0.08 to 0.5 mm, in particular 0.1 to 0.3 mm.

[0041] (2) Drying

[0042] Pressure (absolute pressure, vacuum)

[0043] Vacuum contact dryers have the disadvantage that the material to be dried often begins to foam due to the applied negative pressure. This depends on the ingredients of the material, but especially on the viscosity of the solution to be dried. High-viscosity solutions develop a more stable foam and release the trapped air bubbles only slowly, so that these are still present in the film when applied to the rollers or are just escaping, resulting in an irregular film. Surprisingly, however, it was still possible to use a vacuum double-roller dryer for the highly viscous, pasty alkyl polyglycoside solutions and produce a uniform film on the rollers. Foam development can be reduced by setting a lower vacuum.However, a higher vacuum helps to accelerate the evaporation of water and thus keep the temperature for drying and the corresponding temperature stress for the goods to be dried low.

[0044] The process according to the invention is carried out at an absolute pressure of 5 to 30 mbar. If no interventions are made in the system, such as changing the dosage of the material to be dried, removing the dried material, or briefly opening a closed drying system, an absolute pressure of 15 ± 5 mbar, particularly preferably 15 ± 3 mbar, is maintained.

[0045] Roller rotation speed

[0046] The roller rotation 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 is primarily dependent on the selected roller temperature. The residence time should be as short as possible in view of the temperature load, but long enough to achieve the desired residual moisture content. In the process according to the invention, the roller rotation speed is 1 to 6 revolutions per minute, preferably 2 to 5 rpm, and particularly preferably 3 to 5 rpm.

[0047] Roller temperature

[0048] The selected roller temperature is the most important parameter for the successful drying process of the sugar surfactant solution. The applied roller temperature of a contact dryer causes direct drying through temperature transfer to the material lying on it. It is essential that the heat introduced via the roller is only available for evaporating the water and should not lead to excessive heating of the material being dried. The drying of the material must therefore begin exactly at the time of detachment of the dried layer (curtain). 1 ) from the roller to avoid, on the one hand, a sticky product (drying too briefly) with excessive residual moisture, and, on the other hand, discoloration due to excessive temperature exposure with excessively long drying. Surprisingly, foam formation during dosing was strongly dependent on the roller temperature, with the higher roller temperature being advantageous.

[0049] In the process according to the invention, a roller temperature of 100 to 135 °C, preferably 105 to 120 °C and particularly preferably 113 +- 3 °C is used.

[0050] Higher temperatures cause the material to harden, making it more difficult to achieve uniform comminution. If the temperature is increased further, a partially charred product is obtained.

[0051] The dryer's jacket temperature setting has only a minor impact on the drying process. Jacket temperature control prevents the evaporated liquid from condensing on colder areas (the interior surface! There is no air in a vacuum), so every vacuum drum dryer must be equipped with a jacket heater.

[0052] The jacket temperature also varies depending on the type of fluid. Solutions require significantly lower surface temperatures than water-based fluids.

[0053] For aqueous liquids as in the present case, the jacket temperature should be between 40 - 80 °C, preferably 50 ± 5 °C, to avoid condensation of the water drawn off from the material to be dried on the cooler inner walls of the dryer.

[0054] The type of heating is product-independent; the jacket can be equipped with an electric heating cord, a double jacket containing water or oil, or a tubular coil. The vacuum drum dryer shown in Figure 1, designated number 6, therefore has either a liquid-filled double jacket or a single thick wall (the drawing, without the cavity, is to be understood as the wall thickness of the process chamber), which is heated by an attached heating coil.

[0055] Optimal parameters for the drying process are therefore:

[0056] • Inlet temperature = 40 - 60 °C (temperature of the APG mass introduced into the gap)

[0057] • Absolute pressure = 5 - 30 mbar

[0058] • Roller temperature = 100 - 135 °C

[0059] • Gap width of the rollers = 0.05 - 5 mm

[0060] • Jacket temperature = 40 - 80 °C

[0061] • Roller revolution = 1 - 6 rpm

[0062] Thus, an object of the invention is a

[0063] A drying process for producing anhydrous sugar surfactant granules, in which a) a concentrated alkyl polyglycoside solution with a solids content of 40 to 60 wt. % is heated to 40 - 60 °C and b) the double roller dryer is fed at a continuous speed with the aqueous, tempered, pasty solution from a), wherein the counter-rotating rollers of the double roller dryer with a gap width of 0.05 to 5 mm have a temperature of 100 to 135 °C and the jacket temperature of the dryer is 40 - 80 °C c) and a vacuum of 5 to 25 mbar absolute pressure is applied.

[0064] The preferred method is the one with the following process parameters:

[0065] • Inlet temperature = 50 - 55 °C (temperature of the APG mass introduced into the gap)

[0066] • Absolute pressure = 15 ± 5 mbar

[0067] • Roller temperature = 105 - 120 °C

[0068] • Gap width of the rollers = 0.06 -1.0 mm

[0069] • Jacket temperature = 50 ± 5 °C

[0070] • Roller rotation = 2 - 5 rpm - speed !!! m / s

[0071] The process with the following process parameters is particularly preferred:

[0072] • Inlet temperature = 50 - 55 °C (temperature of the APG mass introduced into the gap)

[0073] • Absolute pressure = 15 ± 5 mbar

[0074] • Roller temperature = 105 - 120 °C

[0075] • Gap width of the rollers = 0.08 -0.5 mm

[0076] • Jacket temperature = 50 ± 5 °C

[0077] • Roller rotation = 3 - 5 rpm The process with the following process parameters is particularly preferred:

[0078] • Inlet temperature = 50 - 55 °C (temperature of the APG mass introduced into the gap)

[0079] • Absolute pressure = 15 ± 3 mbar

[0080] • Roller temperature = 113 ± 3 °C

[0081] • Gap width of the rollers = 0.1 -0.3 mm

[0082] • Jacket temperature = 50 ± 5 °C

[0083] • Roller rotation = 3 - 5 rpm

[0084] (3) Removal of the dried material and, if necessary, post-treatment

[0085] When the dried mass is removed from the rollers, the material to be dried must not be too hot to prevent the detached layer from sticking together (compacting). The temperature of the scraped-off material drops immediately after the material has been scraped off in the dryer chamber and continues to drop after removal from the dryer. The material is collected after scraping off the rollers. This takes place in a lock during continuous dryer operation or in a batch process in a container inside the dryer. The dried material is removed with a residual moisture content of less than 2 wt. %, preferably less than 1.5 wt. %, particularly preferably a maximum of 1 wt. % and, if necessary, ground to improve flowability.

[0086] Furthermore, a flow aid such as silicon dioxide can be added. Other inert flow-regulating additives include any form of silicon dioxide, including fumed silicas, precipitated silicas, aluminum silicates, magnesium silicates, etc., zeolites, bentonites, montmorillonites, and attapulgites, as well as mixtures thereof. The weight of the optionally added flow-regulating inert substance relative to the weight of the total sugar surfactant composition is approximately 0.2:100 to approximately 3:100, more preferably approximately 2:100.

[0087] Alkyl and / or alkenyl polyglycosides

[0088] Alkyl and alkenyl polyglycosides - sometimes also referred to in the literature as alkyl and / or alkenyl oligoglycosides - are well-known non-ionic surfactants that follow the formula (I),

[0089] R 1 O-[G] P (I) in the R 1represents an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G represents a sugar radical having 5 or 6 carbon atoms, and p represents a number from 1 to 10. They can be obtained by the relevant methods of preparative organic chemistry. Reference is made here to EP-A1-0 301 298 and WO 90 / 03977, representative of the extensive literature.

[0090] The alkyl and / or alkenyl polyglycosides can be derived from aldoses or ketoses having 5 or 6 carbon atoms, preferably glucose. The preferred alkyl and / or alkenyl polyglycosides are therefore alkyl and / or alkenyl polyglucosides. The index number p in the general formula (I) indicates the degree of oligomerization (DP), i.e. the distribution of mono- and polyglycosides, and stands for a number between 1 and 10. While p in a given compound must always be an integer and can here primarily assume the values ​​p = 1 to 6, the value p for a specific alkyl polyglycoside is an analytically determined calculated value that is usually a fractional number. Alkyl and / or alkenyl polyglycosides with an average degree of oligomerization p of 1.1 to 3.0 are preferably used.From an application point of view, those alkyl and / or alkenyl polyglycosides are preferred whose degree of oligomerization is less than 2 and in particular between 1.2 and 1.8.

[0091] The alkyl or alkenyl radical R 1can be derived from primary alcohols having 6 to 18, preferably 8 to 14, carbon atoms. Typical examples are 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, palmoleyl alcohol, oleyl alcohol, isostearyl alcohol, and their technical mixtures, such as those obtained, for example, in the hydrogenation of technical fatty acid methyl esters or in the hydrogenation of aldehydes from Roelen's oxosynthesis. Preferred are alkyl polyglucosides of chain length Cs / io (DP = 1 to 3, preferably 1.2 - 1.8), preferably prepared from the alcohol mixture obtained as first runnings from the distillative separation of technical Cs / is coconut fatty alcohol, alkyl polyglucosides of chain length C12 / 14 (DP = 1 to 3, preferably 1.2 - 1.8), preferably based on hydrogenated C12 / 14 coconut alcohol, and alkyl polyglucosides based on technical Cg / n-oxo alcohols (DP = 1 to 3), alkyl polyglucosides of chain length C12-18 (DP = 1 to 3, preferably 1.2 - 1.8).

[0092] Industrial applicability

[0093] The solids obtainable by the process according to the invention can subsequently be blended with other ingredients of powdered surfactants, such as tower powders for detergents. In the field of personal care products, the drying products can be incorporated directly into anhydrous soap bars. It is also easily possible to incorporate the powders into aqueous preparations. Alternatively, the drying products can be easily redispersed in water directly before incorporation into cleaning or cosmetic formulations; drying thus improves the transport of the raw material in terms of space requirements and energy consumption. In fact, no differences in the application properties are observed when using the powders compared to the aqueous starting pastes.The granules can also be easily incorporated into syndet soap formulations, for example, together with fatty acids, fatty acid salts, starch, polyglycols and the like.

[0094] Examples

[0095] Experiment 1 : Laboratory dryer with a drying area of ​​0.22 m 2

[0096] Initial investigations into the drying of a sugar surfactant solution with a solids content of 53% were carried out in a commercially available vacuum double roller dryer from IPT Pergande GmbH (06369 Südliches-Anhalt, OT Weißandt Gölzau) in laboratory size (drying area 0.22 m 2 ) carried out.

[0097] Input material:

[0098] Plantacare 1200 UP (BASF) - INCI: Lauryl Glucoside, a cloudy, highly viscous aqueous solution of C12-C16 fatty alcohol polyglycosides with a dry residue of 53.0 wt.%.

[0099] The material to be dried was preheated to a temperature of 50°C and metered into the gap between the rotating rollers via a gravimetric feeder with valve control. The vacuum applied in the dryer was 15 mbar absolute pressure. The drying behavior of the alkyl polyglycoside paste was tested at different feed rates, roller revolutions, and roller temperatures of 75°C or 120°C. The solid film was scraped off the rollers by blades and collected. The resulting thin sheets of dried solid could be easily ground into a flowable powder with a maximum moisture content of 2.0 wt.% – or 1 wt.% at higher roller temperatures.

[0100] Process parameters: Experiments 1.1 to 1.3 - with a roller temperature of 75°C

[0101] Tests 1.1 and 1.2 - roller temperature of 75 °C Test 1.3 - increased injection power and roller rotation

[0102] Tests 1.4 to 1.6 - with a roller temperature of 120°C

[0103] Experiment 1.4 Experiment 1.5:

[0104] Experiment 1.6: ■ Experiments 1.1 to 1.6 showed that, contrary to experience with conventional drying methods, temperature-controlled and continuous drying of even highly concentrated, viscous sugar surfactant solutions is possible using the vacuum twin-roller dryer. Surprisingly, foam formation during dosing was highly dependent on the roller temperature, with the higher roller temperature being advantageous. The higher roller temperature also enabled an increase in the roller speed, which in turn significantly increased the injection rate (comparison V5 -> V9 || 0.28 kg / h -> 0.48 kg / h).

[0105] Very good results with a high product throughput were achieved in trials 1.4 to 1.6 by pre-heating the material to 50°C and a roller temperature of 120°C. At this roller temperature, a residual moisture content of <1 wt.% was achieved by appropriate parameter settings.

[0106] Test 2: Vacuum double roller dryer with a drying area of ​​0.40 m 2

[0107] To increase the throughput, further tests were carried out to dry a sugar surfactant solution with a solids content of 53% in a commercially available vacuum double roller dryer from IPT Pergande GmbH (06369 Südliches-Anhalt, OT Weißandt Gölzau) with a roller area of ​​0.40 m 2 and the following dryer markings:

[0108] Dryer parameters

[0109] Roller area (total) 0.56 m 2

[0110] Roller area (approx. net) 0.40 m 2

[0111] Roller length 0.37 m

[0112] Roller diameter 0.24 m

[0113] Maximum roller temperature: 160 °C (depending on the thermostat's power)

[0114] Gap width between the rollers 0.1 mm to 0.3 mm

[0115] Pressure range 10 mbar - ambient pressure

[0116] Speed ​​0.5 rpm to 3.0 rpm

[0117] Input material:

[0118] Plantacare 1200 UP (BASF) - INCI: Lauryl Glucoside, a cloudy, highly viscous aqueous solution of C12-C16 fatty alcohol polyglycosides with a dry residue of 53.0 wt.%.

[0119]

[0120] Test series 2.1, 2.2, 2.3 and 2.4 were carried out on a larger double-roller dryer to determine the optimal printing range.

[0121] The result shows a clear dependence between the pressure level and the achieved drying performance.

[0122] Visually, it was observed that at higher pressure (lower vacuum), the continuity of a continuous product layer on the rollers decreased, meaning there was less product wetting. This also resulted in lower drying performance.

[0123] Tests on the residence time of the product - influence of roller temperature and speed

[0124] A change in the roller speed has a noticeable influence on the product quality, ie if the temperature load is too long - determined by the roller temperature and residence time - the product turns into a melt.

[0125] The first dried products (tests 2.5 and 2.6) exhibited a glassy, ​​very solid material that resembled a melt. This high strength also meant that the product required higher energy consumption for milling. By reducing the roller temperature from 120°C to 112°C, the product quality was significantly improved.

[0126] The formation of the melt was not observed in the first series of tests at 120 °C, since the higher speed (4.0 rpm instead of 3.0 rpm) in tests 1.4 to 1.6 led to a shorter residence time of the material on the roll of approximately 14 s.

[0127]

[0128]

[0129] Summary of results:

[0130] The dried material of test series 1 and 2 was mechanically treated by grinding after the end of the process in order to obtain uniform, free-flowing powders.

[0131] To obtain a homogeneous powdered dry product, the product strands or curtain-like shapes were subjected to grinding after 12 hours of cooling in a nitrogen atmosphere.

[0132] ■ Grinding was carried out in an EIRICH R02 intensive mixer with a capacity of 3 to 5 liters and a diameter of 235 mm. The mixer features a two-stage speed control and a counter-rotating movement between the stirrer and the plate.

[0133] ■ The grinding time was 30 seconds each

[0134] ■ the quality of the grinding of the dried product was very good regardless of the product form (curtain form or product roll)

Claims

Patent claims 1 . A process for the preparation of anhydrous sugar surfactant granules, in which an aqueous paste of alkyl and / or alkenyl polyglycosides with a solids content of 40 - 60 wt.%, heated to at least 40°C, is dried in a vacuum double-roller dryer with a specific drying capacity of 3 to 7 kg / m 2 / h at a roller temperature of 100 to 130 °C.

2. Process according to claim 1, characterized in that the dryer is operated at a vacuum of 5 to 25 mbar absolute pressure.

3. Process according to claims 1 and / or 2, characterized in that the rollers have a gap width of 0.05 to 5 mm.

4. Method according to at least one of claims 1 to 3, characterized in that the roller rotation speed is 1 to 6 revolutions per minute.

5. Process according to at least one of claims 1 to 4, characterized in that alkyl polyglycosides of the formula (I) are used, R 1 O-[G] P (I) in the R 1 stands for an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G stands for a sugar radical having 5 or 6 carbon atoms and p stands for numbers from 1 to 10.

6. Process according to at least one of claims 1 to 5, characterized in that the double roller dryer is used with a roller temperature of 105 to 120°C.

7. Process according to at least one of claims 1 to 6, characterized in that the drying process is carried out at an absolute pressure (vacuum) of 15 ± 5 mbar, preferably 15 ± 3 mbar.

8. Process according to at least one of claims 1 to 7, characterized in that the double-roller dryer is used with a jacket temperature of 50 ± 5 °C.

9. Process according to at least one of claims 1 to 8, characterized in that the double roller dryer is used with roller rotation of 1 to 6 rpm, preferably 2 to 5 rpm, particularly preferably 3 to 5 rpm.

10. A process according to at least one of claims 1 to 9, characterized in that the dried product obtained is then ground.

11. Sugar surfactant granules produced according to at least one of the preceding claims, characterized in that the residual moisture is below 1.5, preferably below 1.0 wt.%.

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