MXPA97000863A - Granulation in a fluidized bed - Google Patents

Abstract

A process for the manufacture of detergent powders comprising fluidizing a particulate material forming a neutralizing agent, preferably in a fluid bed, contacting LAS with the fluidized material to effect the neutralization and optionally the addition of a flow aid is described. to the material either before, during or subsequent to the addition of acid L

Description

Granulation in a fluidized bed The present invention relates to a detergent composition with low volumetric density (DV) and a process for its production by means of dry neutralization and further comprises the use of a fluidized bed for the manufacture of such detergent compositions. The spray drying process is known in the industry to obtain powder detergents. However, said spray drying process is affected by the disadvantage of being expensive both in capital and in energy and consequently, the product obtained is expensive. At the same time, an advantage derived from said process is that the powders have a low volumetric density of 350 to 600 g / L. Henkel 4304062 describes the process of an active surfactant and cleaner granulate in which an anionic surfactant in acid form is neutralized with an aqueous alkaline solution under high gaseous pressure in a granulation and drying chamber. An essential step in this process is the drying of a non-surfactant liquid component through the use of hot air. The dry neutralization process for preparing powdered detergents is known in the industry but this often results in powders with low bulk density. The Indian Patent No. 166307, (Hindustan Lever Ltd) refers to the specific use of a fluidized bed of internal recirculation and mentions that the use of a conventional fluidized bed will lead to a sticky and lumpy process. The East German Patent No. 140 987 (VEB aschmittelverk) describes a continuous process for the production of granular washing and cleaning compounds, in which liquid components such as nonionic surfactants or acid precursors of anionic surfactants are sprayed on a dusted builder material, especially sodium tripolyphosphate (STPP) which has a high phase II content with the purpose of obtaining a product with a volumetric density between 530 and 580 g / L. However, the process, according to the aforementioned German patent, is restricted to the use of STPP with a high content of phase II. GB1404317 describes the preparation of a powder detergent with low or moderate volumetric density by means of a dry neutralization process. Sulfonic acid is mixed with a surplus of bicarbonate ash in the presence of water in sufficient quantity to initiate the neutralization reaction but not so much as to wet the resulting product which is in fine powder form. The process is carried out in a mixing apparatus, for example a belt mixer, a planetary or air transfer mixer. In said mixing apparatus, the particulate detergent material (fragmented into particles) is subject to compressive forces that could lead to an increase in volumetric density. We have now found that the disadvantages of the above method can be eliminated by neutralizing an acid precursor in a fluidized bed in order to produce a powder with low bulk density. The invention provides, first hand, a process for the production of a fragmented (particulate) detergent composition having a volumetric density in the range of 350 to 650 g / L which involves entering a particulate material consisting of a neutralizing agent and optionally a builder in a fluidization zone, fluidizing the material, contacting a liquid precursor of an anionic surfactant with the fluidized material to effect at least partially, and preferably substantially complete, a neutralization of the acid precursor and also effect the formation of detergent particles that form the now neutralized acid precursor. Preferably, the fluidization zone will be provided by means of a fluid bed. According to a more advanced aspect of the invention, there is provided a process for the production of a particulate detergent composition having a low volumetric density, consisting of: -i. introduce a particulate material, consisting of a builder and a neutralizing agent inside a fluidizing bed; ii. introduce linear alkyl benzene sulfonate acid (LAS) in said bed for a time sufficient to effect at least partial neutralization of the acid and to obtain the required properties in the powder. The invention also provides a detergent composition obtainable by the process defined in the description. The process can be carried out either batchwise or continuously, as desired.

The term "detergent composition" as used will comprise a detergent material that can be mixed with other conventional materials, for example bleach and enzymes to produce a fully formulated product and also a detergent component, which we will often refer to as a attached, which can be further processed in order to produce a detergent material that can then be mixed with other materials if desired. In accordance with the invention, the process describes the dry neutralization of an acid precursor of an anionic surfactant with a neutralizing agent by means of fluidization of the neutralizing agent; the process is preferably carried out in a fluidized bed. The dry neutralization process refers to the partial (and preferably substantially complete) neutralization of the acid precursor while the mixture remains in particulate form. Conveniently, the addition of the acid precursor is controlled so that it does not accumulate in its non-neutralized form in the detergent composition. The neutralizing agent is conveniently particulate and comprises an inorganic alkaline material, preferably an alkaline salt. Suitable materials are alkali metal carbonates and bicarbonates, for example sodium salts. The neutralizing agent will conveniently be present at a level sufficient to completely neutralize the acid precursor. If desired, a stoichiometric excess of neutralizing agent may be employed to ensure complete neutralization or to provide an alternative function, for example construction (accumulation), in the case of sodium carbonate. In addition to the anionic surfactant obtained in the neutralization step, other anionic surfactants or nonionic, cationic, z itteronic, amphoteric or semi-polar surfactants or mixtures thereof can be added at the appropriate time. Suitable surfactants are those generally described in "Surface active agents and detgents", Volume I, by Schwartz and Perry. So if desired, soap derived from saturated or unsaturated fatty acids having from C 12 to C 15 carbon atoms may also be present as an anionic surfactant. The active detergent will suitably be present at a level of 5 to 40%, preferably 12 to 30% of the weight of the detergent composition. Any conventional constructor can be used; Sodium carbonate, zeolite, sodium tripolyphosphate (STPP), sodium citrate and / or high surface area calcite are all suitable builders. The constructor may also consist of any of the aforementioned individually or in combination with other constructors.

The builder and the neutralizing agent can be the same material, for example sodium carbonate; in this case enough material will be used for both functions. The manufacturer will suitably be present at a level of 15 to 65%, preferably 15 to 50% of the weight of the detergent composition. The detergent powder obtained in the present invention has a low volumetric density in the range of 350 to 650 g / L, or 450 to 650 g / L, for example, in the vicinity of 500 g / L and is then comparable to the density volumetric obtained by means of the method of spray drying. Optionally and preferably an auxiliary flow compound will be incorporated into the composition. The flow aid may be mixed with the neutralizing agent and, if present, with the builder prior to or subsequent to the partial or complete addition of the acid precursor. It is especially preferred that the flow aid be added before or after a partial introduction of the acid precursor since in this way a significant reduction in the volume density of the final powder can be achieved.

The flow aid will suitably be present in an amount of 0.1 to 15% of the weight of the detergent composition, preferably in an amount of 0.5 to 5%. Suitable flow auxiliaries are: metallic, amorphous or crystalline alkali silicate, calcite, diatomic earth, silica, for example precipitated silica, magnesium sulfate, and calcium carbonate, for example precipitated calcium carbonate. Mixtures of these materials may be employed as desired. In the preferred form, the flow aid is Dicamol. The composition may also include a particulate filler that will ideally be composed of an inorganic salt, for example sodium sulfate and sodium chloride. The filler may be present at a level of 5 to 50% of the weight of the composition. The detergent composition produced according to the invention is ideally composed of the active detergent and builder and optionally one or more flow aids, fillers and other minor ingredients such as color, perfume, brighteners, bleaches and enzymes. We have also found that a significant reduction in volumetric density can be ensured through the selection of raw materials that have certain particle size characteristics.

Ideally, the particulate materials have a certain particle size distribution such that no more than 5% of their weight have a particle size greater than 250μ. It is also preferred that at least the equivalent of 30% of the weight of the material be of particles having a size less than 75 μ. Ideally the particulate material will have an average particle size of less than 200 μ for detergent powders in which a low volumetric density is particularly desired. If desired, a controlled amount of water can be added to facilitate neutralization. The water may be added in amounts of 0.5 to 2% by weight of the final detergent composition. It is recommended to add this water before, or jointly or alternately with the addition of the acid precursor. Preferably the particulate material is introduced into a fluidized bed and the required amount of LAS acid is then introduced, preferably by spraying it onto the above-mentioned material and preferably from above. If present, the flow aid may be introduced with the starting material, however, it is preferable that the flow aid be added later to the partial introduction of part of the LAS acid to obtain a lower bulk density. The fluid bed will ideally be operated in ambient temperatures up to 60 ° C. The air flow is sufficient to cause fluidization and preferably should be in the range of 0.6 to 1 ms "1. The fluidization of the solid material is an essential part of the present invention as this facilitates neutralization and granulation at the time. This can be contrasted with the mixing processes in which the particles are intentionally contacted and compressed, which can lead to dust with higher volumetric density and poorer properties in it. the following non-limiting examples.

EXAMPLES 1 to 19. An alkaline inorganic builder material in powder form (in Examples 1 to 4 both functions are carried out by sodium carbonate) and a filler was introduced into a bed of fluids and fluidized by means of operation at a superficial velocity of the surface. air above the minimum fluidization speed. The temperature in the fluid bed was between ambient and 60 ° C. LAS acid (linear alkyl benzene sulphonic acid) is sprayed onto the powder mixture in the fluid bed. The relative amounts of the various components of the composition were varied and are listed below, in Table 1. Examples 1 to 3 illustrate the effect of incorporating a flow aid (in this case Dicamol) into the composition in various stages of the process. process. In Example 1 the flow aid was not added to the material. In Example 2, the flow aid was added to the starting material before the introduction of the LAS acid. In Example 3, the flow aid was added after the introduction of 50% of the LAS acid. Example 4 illustrates the benefits obtained by employing a fine grade particulate material. The results are shown below, in Table 1. The rate of dissolution of the powder was determined by adding powder to one liter of water to supply a concentration of 1.4%, mixing at 100 r.p.m. and measuring the conductivity of the solution until a constant value was reached. The cited figures refer to the level of dissolved powder after a lapse of approximately 90 seconds TABLE 1 * Dissolution rate * Initially added Dicamol ** Dicamol added after 50% LAS Examples 2 and 3 show that a significant reduction in volumetric density can be achieved by addition of the flow aid either before or after the introduction of part of the LAS acid. Other powders, as detailed in Examples 5 to 19, were prepared according to the process described for Examples 1 to 4 and various raw materials with different particle size distributions were employed. Table 2 summarizes the distribution of the various materials.

TABLE 2 - Properties of various raw materials.

TABLE 3 TABLE 4 TABLE 5 Tables 3 and 4 show the results for powders constructed with STPP containing active in the range of 17 to 31%. The soda ash and the STPP had a similar particle size distribution as shown in Table 2 and the formulations based on such builder systems resulted in products with bulk density close to 500 g / L. Table 5 shows powders based on various systems of constructors, i.e. STPP, soda ash and HSA calcite. Both the soda ash and the STPP constructed the resulting formulations in powders with DV of approximately 500 g / L, while the formulations based on calcite HSA resulted in powders with a volumetric density of less than 500 g / L. Example 19 refers to a composite active system containing 13% LAS and 4% soap and resulted in a powder with a bulk density of 500 g / L.

Claims (7)

1. CLAUSES 1 A process for the production of a particulate detergent composition having a volumetric density in the range of 350 to 650 g / L, and consisting of: feeding a particulate material formed by a neutralizing agent and optionally a builder in a fluidization zone, the fluidization of the material, contacting a liquid acid precursor of an anionic surfactant with the fluidized material in order to effect a partial (preferably substantially complete) neutralization of the acid precursor and to achieve the formation of detergent particles which form the neutralized acid precursor.
2. 2 A process for the introduction of a particulate detergent composition having a volumetric density in the range of 350 to 650 g / L and consisting of: i. the introduction of a particulate material formed by a builder and a neutralizing agent in a fluidized bed; ii. the introduction of linear alkyl benzene sulfonic acid (LAS) in said bed for a time sufficient to effect at least partial neutralization of the acid and achieve the required properties of the powder.
3. 3 A process according to any preceding clause in which the neutralizing agent is formed by an inorganic alkaline material, preferably an alkali metal carbonate.
4. 4 A process according to any preceding clause that includes the step of adding one or more flow auxiliaries in an amount of 0.1 - 1.5% of the weight of the composition.
5. 5 A process according to any preceding clause in which the flow aid is added after the partial addition of the acid precursor.
6. 6 A process according to any of Clauses 1 to 4 in which the flow aid is added before the introduction of the acid precursor.
7. 7 A process according to any preceding clause in which the flow aid is one or more of the following: dicamol, crystalline or amorphous alkali metal silicate, calcite, diatomic earth, precipitated silica and magnesium sulfate. 8 8 A process according to any of the preceding clauses in which the neutralizing agent and other particulate materials have a particle size distribution such that no more than 5% of the particles have a size greater than 250μm and at least 30% the particles have a particle size less than 75 μm. 9 A composition or detergent component consequently obtainable by means of a process according to any preceding clause.